After that I will show you the steps to make a Printed Circuit Board (PCB) from the schematics. <\/p>\n\n\n\n
Een Nederlandse versie van deze post staat op de site van opencircuit.nl<\/p>\n\n\n\n
Principal of Infrared communication<\/strong><\/h2>\n\n\n\nInfrared (IR) communication is a common, inexpensive, and easy to use wireless communication technology. IR light is undetectable to the human eye because it has a slightly longer wavelength (typically 950nm) than normal light (380-780nm) – perfect for wireless communication. An IR remote works by turning a LED on and off in a particular pattern. However, to prevent interference from IR sources such as sunlight or other lights, the LED is not turned on steadily, but is turned on and off at a modulation frequency (typically 36, 38, or 40kHz). <\/p>\n\n\n\n
<\/p>\n\n\n\n
![\"\"](\"https:\/\/willem.aandewiel.nl\/wp-content\/uploads\/2019\/07\/IF_Modulated_Output.png\")
<\/figure><\/div>\n\n\n\nThe time when a modulated signal is being sent is called a mark, and when the LED is off is called a space. Most used IR-remotes use a modulation frequency of 38kHz which means that a mark is represented by a fast (38.000 times\/second) \u201con\/off\u201d switching of the IR LED. <\/p>\n\n\n\n
![\"\"](\"https:\/\/willem.aandewiel.nl\/wp-content\/uploads\/2019\/07\/IR-message.png\")
A typical IR-message <\/strong><\/figcaption><\/figure><\/div>\n\n\n\nAn IR-message starts with a lead-in pulse that is much longer than the other pulses. Then there is a start-bit, then comes the actual data and then again a long pulse, to indicate the end of the IR-message (not shown on the image).<\/p>\n\n\n\n
Design considerations<\/strong><\/h2>\n\n\n\n- an IR-receiver-diode<\/a> to capture the IR-messages <\/li>
- an IR-transmitter<\/a> (IR LED\u2019s 950nm) to send IR-messages <\/li>
- some processing power<\/li>
- storage for saving the captured IR-messages<\/li>
- two status LED\u2019s<\/li>
- the device needs to work with all Infrared remotes that modulate the Infrared signal at 38kHz<\/li>
- it must be able to capture 400 pulse-long messages (I need to be able to capture from and send commands to my Airco\/Heater).<\/li><\/ul>\n\n\n\n
The obvious choice to interface with the device is by using a webserver and restAPI and consequently the device needs an internet connection. The ESP8266 with its builtin WiFi and flash filesystem storage is the logical processor for this project.<\/p>\n\n\n\n
Project setup<\/strong><\/h2>\n\n\n\nThe best way to develop any project is by slicing it into small, logical parts and developing and testing these parts one at the time<\/em>. For now I see three major parts:<\/p>\n\n\n\n- The IR-receiver circuit<\/li>
- The IR-sender circuit<\/li>
- The software to glue everything together<\/li><\/ol>\n\n\n\n
The development will be done with the 1of!-boards<\/a><\/em><\/strong> as they are cheap and easy to use. For the initial setup the 1of!-Wemos<\/a><\/em><\/strong> processor board is the board of choice as it is easily programmed with a USB cable and for the rest of the circuity a 1of!-Solderless bread board<\/em><\/strong> is used. If I\u2019m satisfied with the circuit on the 1of!-Solderless board<\/em><\/strong> I will flash the firmware to a 1of!-ESP12<\/a><\/em><\/strong> <\/a>processor board and build the circuitry on a 1of!-Proto<\/a><\/em><\/strong> board.<\/p>\n\n\n\nThe IR signal processing is handled by a fantastic library<\/a> [v2.6.2 (20190616)] written by Ken Shirriff, David Conran<\/em> and others. For additional details on how the library works, see Ken Shirriff’s blog: A Multi-Protocol Infrared remote Library for the Arduino<\/a>.<\/p>\n\n\n\n\n\n\n\nThe IR-receiver circuit<\/strong><\/h2>\n\n\n\nFor receiving IR-codes an IR-receiver-diode is used. I chose the VS1838B<\/a> which is a commonly used and available part that detects 950nm light at 38kHz.The VS1838B detects the 38kHz modulated IR-message and outputs a logic-pulse.<\/p>\n\n\n\nThe VS1838B detects the 38kHz modulated IR-message and outputs a logic-pulse.<\/p>\n\n\n\n
![\"\"](\"https:\/\/willem.aandewiel.nl\/wp-content\/uploads\/2019\/07\/IR_receiver_circuit.png\")
The IR receiver schematic <\/strong><\/figcaption><\/figure><\/div>\n\n\n\nThe output of the VS1838B is send to GPIO12 of the ESP8266 that will analyse and decode and eventually store the IR-message to a file. <\/p>\n\n\n\n
On the 1of!-Solderless<\/em><\/strong> board it looks like this. (mind you: The final design uses IO-14 for the green LED):<\/p>\n\n\n\n![\"\"](\"https:\/\/willem.aandewiel.nl\/wp-content\/uploads\/2019\/07\/1of-IR_Recv-1024x675.png\")
<\/figure><\/div>\n\n\n\nA green LED (D6) is connected to GPIO14 to give some visual indication the device is waiting for an IR-message to capture.<\/p>\n\n\n\n
You can find a program (IR_receiver<\/a>) to test this setup on github<\/a>.<\/p>\n\n\n\nCompile and flash the IR-receiver sketch to the 1of!-Wemos<\/em><\/strong> (or 1of!-ESP12<\/em><\/strong>) board and open the Serial Monitor.<\/p>\n\n\n\n IR_receiver is now running and waiting for IR input on Pin 12\n \n SPIFFS Mount successful\n \n Commands are:\n \n *D - remove file from SPIFFS\n L - List SPIFFS\n H - Help (this message)\n W - Write rawData to SPIFFS\n S - System Status\n *R - Reboot\n \n Timestamp : 000030.031\n Encoding : NEC\n Code : FFA857 (32 bits)\n Library : v2.6.2\n \n Raw Timing[71]:\n + 9342, - 4392, + 684, - 462, + 658, - 488,\n + 716, - 430, + 656, - 488, + 598, - 546,\n + 684, - 460, + 716, - 428, \n . . . .\n + 658, - 1624, + 660, - 486, + 714, - 1568,\n + 744, - 1516, + 708, - 1594, + 718, - 39748,\n + 9346, - 2124, + 708\n \n uint16_t rawData[71] = {9342, 4392, 684, 462, 658, 488, 716,\n 430, 656, 488, 598, 546, 684, 460, 716, 428, 716, 428, 714,\n 1568, 686, 1596, 688, 1592, 658, 1624, 658, 1602, 738,\n 1564, 664, 1618, \n . . . \n 460, 658, 1624, 660, 486, 714, 1568, 744, 1516, 708, 1594,\n 718, 39748, 9346, 2124, 708}; \/\/ NEC FFA857\n uint32_t address = 0x0;\n uint32_t command = 0x15;\n uint64_t data = 0xFFA857;\n \n [Enter: \u2018w\u2019]\n Write rawData to SPIFFS\n save pulses as: [Enter: \u2018demo3\u2019]\n save pulses as [\/pls\/demo3.pls] (y\/N) [Enter: \u2018y\u2019]\n fileName is [\/pls\/demo3.pls]\n writeRawData(\/pls\/demo3.pls): number of pulses [71]\n 9342, 4392, 684, 462, 658, 488, 716, 430, 656, 488, 598, 546,\n 684, 460, 716, 428, 716, 428, 686, 460, 690, 1590, 688, 458, 688, \n 456, 688, 438, 680, 484, 660, 1622, 684, 460, 658,\n . . . \n 714, 1568, 744, 1516, 708, 1594, 718, 39748, 9346, 2124, 708, \n writeRawData(): saved [71] pulses\n \n [Enter \u2018L\u2019]\n \/pls\/pulse1.pls \/ 286\n \/pls\/demo1.pls \/ 306\n \/pls\/demo3.pls \/ 306 <\/pre>\n\n\n\nThe IR-sender circuit<\/strong><\/h2>\n\n\n\nTo be able to send IR-messages we need one or more IR LED<\/a>\u2019s. Using an IR LED is no different from using a \u201cnormal\u201d LED, except for the fact that to get some reach the IR LED\u2019s need far more current to do their job. Since the GPIO-pins of the ESP8266 are not capable of providing these high currents we need a driver circuit. Easiest is to use an opto-coupler like the 4N35 or 4N25 which doubles as a level-shifter from 3v3 (GPIO04) and 5 Volt to drive the Gate of the MOSFET switch.<\/p>\n\n\n\nThe voltage drop over the IR LED is ~1.6Volt and the maximum current is 60mA. As we are using two IR LED\u2019s in parallel and the duty cycle is 50%, the maximum current through R7 is 60*2*2=240mA. Therefor the value of R7 is (5-1.6)\/240 => ~15 Ohm. <\/p>\n\n\n\n
![\"\"](\"https:\/\/willem.aandewiel.nl\/wp-content\/uploads\/2019\/07\/IR_sender_circuit.png\")
The IR Sender circuit<\/strong><\/figcaption><\/figure><\/div>\n\n\n\nThe pulses come from GPIO04. If GPIO04 is \u201chigh\u201d the led in the optocoupler will ignite and, in turn, sets the transistor to conduct (Pulls the Emitter to 5 Volt). The 5 volt on the Emitter makes the Gate of Q1 \u201chigh\u201d and the MOSFET now also conducts pulling the Drain to ground and so powering the two IR-LED\u2019s (switching them \u201con\u201d).<\/p>\n\n\n\n
A \u201clow\u201d on GPIO04 switches the led in the optocoupler \u201coff\u201d. The transistor opens (no current flows from Collector to Emitter) and R11 pulls the Gate of Q1 to ground. The MOSFET now also does not conduct and no current will flow true the IR-LED\u2019s (switching them \u201coff\u201d).<\/p>\n\n\n\n
![\"\"](\"https:\/\/willem.aandewiel.nl\/wp-content\/uploads\/2019\/07\/1of-IR_Send-1024x675.png\")
This is how it looks on the <\/strong>1of!-Solderless<\/strong><\/em> board <\/strong><\/figcaption><\/figure><\/div>\n\n\n\nMind you: in stead of an IR LED a normal LED is used for testing and therefor the 10 ohm resister (R7) must be 220 ohm!<\/p>\n\n\n\n
You can find a program (IR_sender<\/a>) to test this setup on github<\/a>.<\/p>\n\n\n\nCompile and flash the IR-sender sketch to the 1of!-Wemos<\/em><\/strong> (or 1of!-ESP12<\/em><\/strong>) board and open the Serial Monitor.<\/p>\n\n\n\n \n \n IR_sender is now running and sending IR on pin 4\n \n SPIFFS Mount successful\n \n Commands are:\n \n *D - remove file from SPIFFS\n L - List SPIFFS\n H - Help (this message)\n T - Transmit rawData from SPIFFS\n *R - Reboot\n \n [Enter: \u2018L\u2019]\n [01] [\/pls\/pulse5.pls]\n [02] [\/pls\/pulse1.pls]\n [03] [\/pls\/mutsiCool26.pls]\n [04] [\/pls\/demo1.pls]\n [05] [\/pls\/demo3.pls]\n \n [Enter: \u2018t\u2019]\n Transmit rawData from SPIFFS\n \n Pulse file number: [Enter: \u20183\u2019]\n \n fileName is [\/pls\/mutsiCool26.pls]\n readRawData(\/pls\/mutsiCool26.pls): \n readRawData(): read [307] pulses\n \n\n Sending [307] pulses .. (redled blinks) <\/pre>\n\n\n\nAs the basics are working we can solder the IR-sender and IR-receiver circuitry\u2019s to a 1of!-Proto<\/em><\/strong> board. <\/p>\n\n\n\n![\"\"](\"https:\/\/willem.aandewiel.nl\/wp-content\/uploads\/2019\/07\/1of-Proto-Signal-Leds-1024x857.jpg\")
First the signal LED\u2019s <\/strong><\/figcaption><\/figure><\/div>\n\n\n\nAfter confirming the signal-LED\u2019s blink solder the rest of the circuit:<\/p>\n\n\n\n
![\"\"](\"https:\/\/willem.aandewiel.nl\/wp-content\/uploads\/2019\/07\/1of-Proto_Finished2-1024x715.png\")
<\/figure><\/div>\n\n\n\nI must say, the range of the IR-sender circuit is not as good as I expected. Why is my TV-remote capable of switching channels by pointing it to the opposite wall and does my IR-sender needs to be pointed exactly to my TV? So I reversed engineered two of my remotes and was surprised that they use (almost) the same circuit to drive the IR-LED’s only they have both left out the serie resister<\/em> (R7)!! As I do not want to blow my IR-LED’s I have reduced R7 to only 1 ohm and that enlarged the range quite a bit!<\/p>\n\n\n\n\n\n\n\nThe Firmware to glue everything together<\/strong><\/h2>\n\n\n\nThe firmware uses Web Sockets to interface with the browser. When accessing the URL of the device a simple index.html page is loaded. This page uses Javascript to setup the WebSocket communication between the IR IoT Remote<\/strong><\/em> and the browser.<\/p>\n\n\n\n![\"\"](\"https:\/\/willem.aandewiel.nl\/wp-content\/uploads\/2019\/07\/IR_IoT_Remote_Control.png\")
Main Control Window<\/figcaption><\/figure><\/div>\n\n\n\nThe firmware is still ‘Work in Progress<\/em>‘!<\/p>\n\n\n\n![\"\"](\"https:\/\/willem.aandewiel.nl\/wp-content\/uploads\/2019\/07\/IR_IoT_Remote_Learn.png\")
Learn Window<\/figcaption><\/figure><\/div>\n\n\n\n![\"\"](\"https:\/\/willem.aandewiel.nl\/wp-content\/uploads\/2019\/07\/IR_IoT_Remote_Edit.png\")
Edit Labels and Order<\/figcaption><\/figure><\/div>\n\n\n\n![\"\"](\"https:\/\/willem.aandewiel.nl\/wp-content\/uploads\/2019\/07\/IR_IoT_Remote_FSexplorer.png\")
FS explorer<\/figcaption><\/figure><\/div>\n\n\n\nYou can find the firmware (IR_IoT_Remote) on github<\/a>.<\/p>\n\n\n\nFuture Extentions<\/strong><\/h2>\n\n\n\nExternal Keyboard<\/h3>\n\n\n\n
For some people a web interface is not ideal. For those I added a keyboard interface (J7) that communicates with a keyboard like this<\/a>. The output is a voltage depending on the key pressed. The ADC pin of the ESP-12 can analyse this voltage to decide which key is pressed and send an IR-command depending on that key.<\/p>\n\n\n\nMind you, the firmware has no function for this. You have to make it yourself.<\/em><\/p>\n\n\n\nTemperature Sensor<\/h3>\n\n\n\n
It is fairly simple to implement an interface for a DS18B20 one-wire temperature sensor. You can connect a DS18B20 via port J5.<\/p>\n\n\n\n\n\n\n\n
Making the One of a Kind version<\/strong><\/h2>\n\n\n\nNow everything is in place most of the work for making an One of a Kind<\/em><\/strong> device is done. Whats left is placing the 1of!-Processor<\/em><\/strong> and 1of!-Proto<\/em><\/strong> boards in a project box like this<\/a> one or this<\/a> one. <\/p>\n\n\n\n![\"\"](\"https:\/\/willem.aandewiel.nl\/wp-content\/uploads\/2019\/07\/1of-Enclosure-c-1024x620.jpg\")
<\/figure><\/li>![\"\"](\"https:\/\/willem.aandewiel.nl\/wp-content\/uploads\/2019\/07\/1of-Enclosure-b-1024x768.jpg\")
<\/figure><\/li><\/ul><\/figure>\n\n\n\nIt makes a neat enclosure with the (IR) LED\u2019s on one end and an USB power connector at the other end. Of course I have swapped the 1of!-Wemos<\/em><\/strong> board for a 1of!-ESP12<\/em><\/strong>.<\/p>\n\n\n\nMaking a Printed Circuit Board (PCB)<\/strong><\/h2>\n\n\n\nThis is not a comprehensive guide on how to use KiCAD as there are tons of posts on the web and dozens of good books<\/a> for that. I just want to show you the steps involved in the hope you will give it a try! Although KiCAD has a very steep learning curve, for me it is one of the best tools you can use for designing your own PCB\u2019s.<\/p>\n\n\n\nTo be able to design a PCB for this device we need to combine the schematics of the 1of!-ESP12<\/em><\/strong> processor board and the schematic of the IR-receiver and IR-sender.<\/p>\n\n\n\nIn KiCAD you can import an existing schematic sheet into the schematic you are working on.<\/p>\n\n\n\n
So, start with a new, empty sheet. In the File-menu select [Append Schematic Sheet]<\/p>\n\n\n\n
![\"\"](\"https:\/\/willem.aandewiel.nl\/wp-content\/uploads\/2019\/07\/Append-Schematic-Sheet.png\")
<\/figure><\/div>\n\n\n\nThen select the 1of!-ESP12.sch<\/a> file (it\u2019s in the map KiCad<\/em> on the github<\/a> repository).<\/p>\n\n\n\n![\"\"](\"https:\/\/willem.aandewiel.nl\/wp-content\/uploads\/2019\/07\/Append_1of-ESP12.png\")
<\/figure><\/div>\n\n\n\nRemove the 20-pin connector. Select the remaining objects and move them outside the sheet.<\/p>\n\n\n\n
Now again select [Append Schematic Sheet] from the File-menu and select the Schematic for the IR-receiver and sender<\/a> (you can find it in the map KiCad<\/em> on the github<\/a> repository).<\/p>\n\n\n\nRemove the connector and move everything around till you have something like this:<\/p>\n\n\n\n![\"\"](\"https:\/\/willem.aandewiel.nl\/wp-content\/uploads\/2019\/07\/EeSchema_Combined-1024x702.png\")
<\/a><\/figure>\n\n\n\n![\"\"](\"https:\/\/willem.aandewiel.nl\/wp-content\/uploads\/2019\/07\/Annotate-button.png\")
<\/figure><\/div>\n\n\n\nAll field references have a question mark (?) so you need to press the annotate button.<\/p>\n\n\n\n
After that all fields have a unique reference. Don’t worry, if your references are different from the ones in this post!<\/p>\n\n\n\n
![\"\"](\"https:\/\/willem.aandewiel.nl\/wp-content\/uploads\/2019\/07\/AssignFootprintsToSymbols.png\")
<\/figure><\/div>\n\n\n\nNext we need to associate physical parts to the parts in the schematic. This is done by assigning footprints to schematic symbols. <\/p>\n\n\n\n
![\"\"](\"https:\/\/willem.aandewiel.nl\/wp-content\/uploads\/2019\/07\/KiCAD_Assign_Footprints-1024x674.png\")
<\/a><\/figure><\/div>\n\n\n\nA new window pops-up. Most symbols are already assigned a footprint. For those that are empty you need to select the correct footprint from the right part of the window. On the left part of the window you can select specific groups of footprints. You can also create your own footprints with the footprint-editor and place them in a container of your own.<\/p>\n\n\n\n
![\"\"](\"https:\/\/willem.aandewiel.nl\/wp-content\/uploads\/2019\/07\/KiCAD_Netlist.png\")
<\/figure><\/div>\n\n\n\nNext step is to generate a netlist. A netlist is the translation of the schematic to the PCB design.<\/p>\n\n\n\n
![\"\"](\"https:\/\/willem.aandewiel.nl\/wp-content\/uploads\/2019\/07\/KiCAD_PCBnew.png\")
<\/figure><\/div>\n\n\n\nPress the PCBnew icon ..<\/p>\n\n\n\n
![\"\"](\"https:\/\/willem.aandewiel.nl\/wp-content\/uploads\/2019\/07\/KiCAD_Confirm_New_PCB.png\")
<\/figure><\/div>\n\n\n\n.. and a pop-up window will appear ..<\/p>\n\n\n\n
.. asking if it\u2019s OK to create a new PCB (this pop-up will only appear when there\u2019s not already a PCB design).<\/p>\n\n\n\n
Press [Yes] and an empty design window will open. In this window press the [Netlist] icon and select the [Read Current Netlist] to use the Netlist you created in the previous step and press [Close] to close this pop-up window.<\/p>\n\n\n\n![\"\"](\"https:\/\/willem.aandewiel.nl\/wp-content\/uploads\/2019\/07\/KiCAD_Read_Netlist.png\")
<\/a><\/figure>\n\n\n\n![\"\"](\"https:\/\/willem.aandewiel.nl\/wp-content\/uploads\/2019\/07\/KiCAD_InitialNetlist.png\")
<\/a>Next you\u2019ll see the so called <\/strong>rats nest<\/strong><\/em> of components and wires that connects them. <\/strong><\/figcaption><\/figure>\n\n\n\nThe big challenge is to move all the components to a logical place and connect them with copper traces till all the white lines in the rats nest<\/em> are gone..<\/p>\n\n\n\n![\"\"](\"https:\/\/willem.aandewiel.nl\/wp-content\/uploads\/2019\/07\/KiCAD_Parts_Placed-1024x744.png\")
<\/a><\/figure>\n\n\n\nTime to lay the copper traces.<\/p>\n\n\n\n![\"\"](\"https:\/\/willem.aandewiel.nl\/wp-content\/uploads\/2019\/07\/KiCAD_Complete-1024x624.png\")
<\/a><\/figure>\n\n\n\n![\"\"](\"https:\/\/willem.aandewiel.nl\/wp-content\/uploads\/2019\/07\/KiCAD_Complete_3D-1024x620.png\")
<\/a>And then it will look like this in 3D <\/strong><\/figcaption><\/figure>\n\n\n\n\n\n\n\nBasic Electronics<\/strong><\/h2>\n\n\n\nCalculating the series-resistor for a LED<\/h3>\n\n\n\n
For every LED, in order to use it properly, we need to know its Forward Voltage. The Forward Voltage (Vf<\/em>) is the voltage used by the LED when it\u2019s \u201con\u201d. <\/p>\n\n\n\n![\"\"](\"https:\/\/willem.aandewiel.nl\/wp-content\/uploads\/2019\/07\/ColeredLed_Vf_If.png\")
<\/figure><\/div>\n\n\n\nAs you can see from the image Vf<\/em> depends on the color of the LED. <\/p>\n\n\n\nThe Forward Current (If<\/em>) is the current at which the LED is at its brightest. <\/p>\n\n\n\nAccording to Kirchhoff’s Voltage Law<\/em> (KVL) the voltage used by a circuit, in this case the LED in series with the resistor (R), must be equal to the voltage applied (in the image 5.0 volt). If the (green) LED\u2019s Vf<\/em> is 2.2 volt, the voltage over the resistor must be 5.0 – 2.2 = 2.8 volt. If the max. current is 20mA the value of the resistor must be 2.8 \/ 0.02 = 140 \u03a9.<\/p>\n\n\n\nThat is, 140 \u03a9 for the LED at its brightest but even with much less current, say 10mA, the LED will be bright enough. At 10mA the Vf<\/em> is 2 volt which results in a resistor of 3 \/ 0.01 = 300 \u03a9.<\/p>\n\n\n\nAs a rule of thumb a 220 \u03a9 resistor is suitable for all red and green LED\u2019s in the range of 3v3 to 5 volt. <\/p>\n\n\n\n
Calculating the series-resistor for the 4N35<\/h3>\n\n\n\n
According to the data-sheet of the 4N35 the Vf<\/em> of the input diode is ~1 volt and If<\/em> is 10mA. As we drive the 4N35 from one of the GPIO-pins of the ESP8266 the applied voltage is 3v3. The voltage over the resistor is 3v3 – 1 = 2.3 volt. This gives a value for the series resistor of 2.3 \/ 0.01 = 230 \u03a9.<\/p>\n\n\n\nThe VS1838<\/h3>\n\n\n\n
This component is called a IR-detector diode but it is far more than only a diode. It has all the circuitry to detect a modulated IR signal and convert the IR signal into a logic output.<\/p>\n\n\n\n![\"\"](\"https:\/\/willem.aandewiel.nl\/wp-content\/uploads\/2019\/07\/BlockDiagram-IR-receiver.png\")
Block diagram VS1838 <\/strong><\/figcaption><\/figure>\n","protected":false},"excerpt":{"rendered":"[ ] In this post I will guide you through the process of building a device that can capture Infrared-messages from an Infrared remote controller (learning mode), and resend the captured Infrared-messages (sending mode). I will use the affordable and … Continue reading
<\/figure><\/div>\n\n\n\nThe time when a modulated signal is being sent is called a mark, and when the LED is off is called a space. Most used IR-remotes use a modulation frequency of 38kHz which means that a mark is represented by a fast (38.000 times\/second) \u201con\/off\u201d switching of the IR LED. <\/p>\n\n\n\n
An IR-message starts with a lead-in pulse that is much longer than the other pulses. Then there is a start-bit, then comes the actual data and then again a long pulse, to indicate the end of the IR-message (not shown on the image).<\/p>\n\n\n\n
Design considerations<\/strong><\/h2>\n\n\n\n- an IR-receiver-diode<\/a> to capture the IR-messages <\/li>
- an IR-transmitter<\/a> (IR LED\u2019s 950nm) to send IR-messages <\/li>
- some processing power<\/li>
- storage for saving the captured IR-messages<\/li>
- two status LED\u2019s<\/li>
- the device needs to work with all Infrared remotes that modulate the Infrared signal at 38kHz<\/li>
- it must be able to capture 400 pulse-long messages (I need to be able to capture from and send commands to my Airco\/Heater).<\/li><\/ul>\n\n\n\n
The obvious choice to interface with the device is by using a webserver and restAPI and consequently the device needs an internet connection. The ESP8266 with its builtin WiFi and flash filesystem storage is the logical processor for this project.<\/p>\n\n\n\n
Project setup<\/strong><\/h2>\n\n\n\nThe best way to develop any project is by slicing it into small, logical parts and developing and testing these parts one at the time<\/em>. For now I see three major parts:<\/p>\n\n\n\n- The IR-receiver circuit<\/li>
- The IR-sender circuit<\/li>
- The software to glue everything together<\/li><\/ol>\n\n\n\n
The development will be done with the 1of!-boards<\/a><\/em><\/strong> as they are cheap and easy to use. For the initial setup the 1of!-Wemos<\/a><\/em><\/strong> processor board is the board of choice as it is easily programmed with a USB cable and for the rest of the circuity a 1of!-Solderless bread board<\/em><\/strong> is used. If I\u2019m satisfied with the circuit on the 1of!-Solderless board<\/em><\/strong> I will flash the firmware to a 1of!-ESP12<\/a><\/em><\/strong> <\/a>processor board and build the circuitry on a 1of!-Proto<\/a><\/em><\/strong> board.<\/p>\n\n\n\nThe IR signal processing is handled by a fantastic library<\/a> [v2.6.2 (20190616)] written by Ken Shirriff, David Conran<\/em> and others. For additional details on how the library works, see Ken Shirriff’s blog: A Multi-Protocol Infrared remote Library for the Arduino<\/a>.<\/p>\n\n\n\n\n\n\n\nThe IR-receiver circuit<\/strong><\/h2>\n\n\n\nFor receiving IR-codes an IR-receiver-diode is used. I chose the VS1838B<\/a> which is a commonly used and available part that detects 950nm light at 38kHz.The VS1838B detects the 38kHz modulated IR-message and outputs a logic-pulse.<\/p>\n\n\n\nThe VS1838B detects the 38kHz modulated IR-message and outputs a logic-pulse.<\/p>\n\n\n\n
The IR receiver schematic <\/strong><\/figcaption><\/figure><\/div>\n\n\n\nThe output of the VS1838B is send to GPIO12 of the ESP8266 that will analyse and decode and eventually store the IR-message to a file. <\/p>\n\n\n\n
On the 1of!-Solderless<\/em><\/strong> board it looks like this. (mind you: The final design uses IO-14 for the green LED):<\/p>\n\n\n\n<\/figure><\/div>\n\n\n\nA green LED (D6) is connected to GPIO14 to give some visual indication the device is waiting for an IR-message to capture.<\/p>\n\n\n\n
You can find a program (IR_receiver<\/a>) to test this setup on github<\/a>.<\/p>\n\n\n\nCompile and flash the IR-receiver sketch to the 1of!-Wemos<\/em><\/strong> (or 1of!-ESP12<\/em><\/strong>) board and open the Serial Monitor.<\/p>\n\n\n\n IR_receiver is now running and waiting for IR input on Pin 12\n \n SPIFFS Mount successful\n \n Commands are:\n \n *D - remove file from SPIFFS\n L - List SPIFFS\n H - Help (this message)\n W - Write rawData to SPIFFS\n S - System Status\n *R - Reboot\n \n Timestamp : 000030.031\n Encoding : NEC\n Code : FFA857 (32 bits)\n Library : v2.6.2\n \n Raw Timing[71]:\n + 9342, - 4392, + 684, - 462, + 658, - 488,\n + 716, - 430, + 656, - 488, + 598, - 546,\n + 684, - 460, + 716, - 428, \n . . . .\n + 658, - 1624, + 660, - 486, + 714, - 1568,\n + 744, - 1516, + 708, - 1594, + 718, - 39748,\n + 9346, - 2124, + 708\n \n uint16_t rawData[71] = {9342, 4392, 684, 462, 658, 488, 716,\n 430, 656, 488, 598, 546, 684, 460, 716, 428, 716, 428, 714,\n 1568, 686, 1596, 688, 1592, 658, 1624, 658, 1602, 738,\n 1564, 664, 1618, \n . . . \n 460, 658, 1624, 660, 486, 714, 1568, 744, 1516, 708, 1594,\n 718, 39748, 9346, 2124, 708}; \/\/ NEC FFA857\n uint32_t address = 0x0;\n uint32_t command = 0x15;\n uint64_t data = 0xFFA857;\n \n [Enter: \u2018w\u2019]\n Write rawData to SPIFFS\n save pulses as: [Enter: \u2018demo3\u2019]\n save pulses as [\/pls\/demo3.pls] (y\/N) [Enter: \u2018y\u2019]\n fileName is [\/pls\/demo3.pls]\n writeRawData(\/pls\/demo3.pls): number of pulses [71]\n 9342, 4392, 684, 462, 658, 488, 716, 430, 656, 488, 598, 546,\n 684, 460, 716, 428, 716, 428, 686, 460, 690, 1590, 688, 458, 688, \n 456, 688, 438, 680, 484, 660, 1622, 684, 460, 658,\n . . . \n 714, 1568, 744, 1516, 708, 1594, 718, 39748, 9346, 2124, 708, \n writeRawData(): saved [71] pulses\n \n [Enter \u2018L\u2019]\n \/pls\/pulse1.pls \/ 286\n \/pls\/demo1.pls \/ 306\n \/pls\/demo3.pls \/ 306 <\/pre>\n\n\n\nThe IR-sender circuit<\/strong><\/h2>\n\n\n\nTo be able to send IR-messages we need one or more IR LED<\/a>\u2019s. Using an IR LED is no different from using a \u201cnormal\u201d LED, except for the fact that to get some reach the IR LED\u2019s need far more current to do their job. Since the GPIO-pins of the ESP8266 are not capable of providing these high currents we need a driver circuit. Easiest is to use an opto-coupler like the 4N35 or 4N25 which doubles as a level-shifter from 3v3 (GPIO04) and 5 Volt to drive the Gate of the MOSFET switch.<\/p>\n\n\n\nThe voltage drop over the IR LED is ~1.6Volt and the maximum current is 60mA. As we are using two IR LED\u2019s in parallel and the duty cycle is 50%, the maximum current through R7 is 60*2*2=240mA. Therefor the value of R7 is (5-1.6)\/240 => ~15 Ohm. <\/p>\n\n\n\n
The IR Sender circuit<\/strong><\/figcaption><\/figure><\/div>\n\n\n\nThe pulses come from GPIO04. If GPIO04 is \u201chigh\u201d the led in the optocoupler will ignite and, in turn, sets the transistor to conduct (Pulls the Emitter to 5 Volt). The 5 volt on the Emitter makes the Gate of Q1 \u201chigh\u201d and the MOSFET now also conducts pulling the Drain to ground and so powering the two IR-LED\u2019s (switching them \u201con\u201d).<\/p>\n\n\n\n
A \u201clow\u201d on GPIO04 switches the led in the optocoupler \u201coff\u201d. The transistor opens (no current flows from Collector to Emitter) and R11 pulls the Gate of Q1 to ground. The MOSFET now also does not conduct and no current will flow true the IR-LED\u2019s (switching them \u201coff\u201d).<\/p>\n\n\n\n
This is how it looks on the <\/strong>1of!-Solderless<\/strong><\/em> board <\/strong><\/figcaption><\/figure><\/div>\n\n\n\nMind you: in stead of an IR LED a normal LED is used for testing and therefor the 10 ohm resister (R7) must be 220 ohm!<\/p>\n\n\n\n
You can find a program (IR_sender<\/a>) to test this setup on github<\/a>.<\/p>\n\n\n\nCompile and flash the IR-sender sketch to the 1of!-Wemos<\/em><\/strong> (or 1of!-ESP12<\/em><\/strong>) board and open the Serial Monitor.<\/p>\n\n\n\n \n \n IR_sender is now running and sending IR on pin 4\n \n SPIFFS Mount successful\n \n Commands are:\n \n *D - remove file from SPIFFS\n L - List SPIFFS\n H - Help (this message)\n T - Transmit rawData from SPIFFS\n *R - Reboot\n \n [Enter: \u2018L\u2019]\n [01] [\/pls\/pulse5.pls]\n [02] [\/pls\/pulse1.pls]\n [03] [\/pls\/mutsiCool26.pls]\n [04] [\/pls\/demo1.pls]\n [05] [\/pls\/demo3.pls]\n \n [Enter: \u2018t\u2019]\n Transmit rawData from SPIFFS\n \n Pulse file number: [Enter: \u20183\u2019]\n \n fileName is [\/pls\/mutsiCool26.pls]\n readRawData(\/pls\/mutsiCool26.pls): \n readRawData(): read [307] pulses\n \n\n Sending [307] pulses .. (redled blinks) <\/pre>\n\n\n\nAs the basics are working we can solder the IR-sender and IR-receiver circuitry\u2019s to a 1of!-Proto<\/em><\/strong> board. <\/p>\n\n\n\n First the signal LED\u2019s <\/strong><\/figcaption><\/figure><\/div>\n\n\n\nAfter confirming the signal-LED\u2019s blink solder the rest of the circuit:<\/p>\n\n\n\n
<\/figure><\/div>\n\n\n\nI must say, the range of the IR-sender circuit is not as good as I expected. Why is my TV-remote capable of switching channels by pointing it to the opposite wall and does my IR-sender needs to be pointed exactly to my TV? So I reversed engineered two of my remotes and was surprised that they use (almost) the same circuit to drive the IR-LED’s only they have both left out the serie resister<\/em> (R7)!! As I do not want to blow my IR-LED’s I have reduced R7 to only 1 ohm and that enlarged the range quite a bit!<\/p>\n\n\n\n\n\n\n\nThe Firmware to glue everything together<\/strong><\/h2>\n\n\n\nThe firmware uses Web Sockets to interface with the browser. When accessing the URL of the device a simple index.html page is loaded. This page uses Javascript to setup the WebSocket communication between the IR IoT Remote<\/strong><\/em> and the browser.<\/p>\n\n\n\nMain Control Window<\/figcaption><\/figure><\/div>\n\n\n\nThe firmware is still ‘Work in Progress<\/em>‘!<\/p>\n\n\n\nLearn Window<\/figcaption><\/figure><\/div>\n\n\n\nEdit Labels and Order<\/figcaption><\/figure><\/div>\n\n\n\nFS explorer<\/figcaption><\/figure><\/div>\n\n\n\nYou can find the firmware (IR_IoT_Remote) on github<\/a>.<\/p>\n\n\n\nFuture Extentions<\/strong><\/h2>\n\n\n\nExternal Keyboard<\/h3>\n\n\n\n
For some people a web interface is not ideal. For those I added a keyboard interface (J7) that communicates with a keyboard like this<\/a>. The output is a voltage depending on the key pressed. The ADC pin of the ESP-12 can analyse this voltage to decide which key is pressed and send an IR-command depending on that key.<\/p>\n\n\n\nMind you, the firmware has no function for this. You have to make it yourself.<\/em><\/p>\n\n\n\nTemperature Sensor<\/h3>\n\n\n\n
It is fairly simple to implement an interface for a DS18B20 one-wire temperature sensor. You can connect a DS18B20 via port J5.<\/p>\n\n\n\n\n\n\n\n
Making the One of a Kind version<\/strong><\/h2>\n\n\n\nNow everything is in place most of the work for making an One of a Kind<\/em><\/strong> device is done. Whats left is placing the 1of!-Processor<\/em><\/strong> and 1of!-Proto<\/em><\/strong> boards in a project box like this<\/a> one or this<\/a> one. <\/p>\n\n\n\n<\/figure><\/li><\/figure><\/li><\/ul><\/figure>\n\n\n\nIt makes a neat enclosure with the (IR) LED\u2019s on one end and an USB power connector at the other end. Of course I have swapped the 1of!-Wemos<\/em><\/strong> board for a 1of!-ESP12<\/em><\/strong>.<\/p>\n\n\n\nMaking a Printed Circuit Board (PCB)<\/strong><\/h2>\n\n\n\nThis is not a comprehensive guide on how to use KiCAD as there are tons of posts on the web and dozens of good books<\/a> for that. I just want to show you the steps involved in the hope you will give it a try! Although KiCAD has a very steep learning curve, for me it is one of the best tools you can use for designing your own PCB\u2019s.<\/p>\n\n\n\nTo be able to design a PCB for this device we need to combine the schematics of the 1of!-ESP12<\/em><\/strong> processor board and the schematic of the IR-receiver and IR-sender.<\/p>\n\n\n\nIn KiCAD you can import an existing schematic sheet into the schematic you are working on.<\/p>\n\n\n\n
So, start with a new, empty sheet. In the File-menu select [Append Schematic Sheet]<\/p>\n\n\n\n
<\/figure><\/div>\n\n\n\nThen select the 1of!-ESP12.sch<\/a> file (it\u2019s in the map KiCad<\/em> on the github<\/a> repository).<\/p>\n\n\n\n<\/figure><\/div>\n\n\n\nRemove the 20-pin connector. Select the remaining objects and move them outside the sheet.<\/p>\n\n\n\n
Now again select [Append Schematic Sheet] from the File-menu and select the Schematic for the IR-receiver and sender<\/a> (you can find it in the map KiCad<\/em> on the github<\/a> repository).<\/p>\n\n\n\nRemove the connector and move everything around till you have something like this:<\/p>\n\n\n\n<\/a><\/figure>\n\n\n\n<\/figure><\/div>\n\n\n\nAll field references have a question mark (?) so you need to press the annotate button.<\/p>\n\n\n\n
After that all fields have a unique reference. Don’t worry, if your references are different from the ones in this post!<\/p>\n\n\n\n
<\/figure><\/div>\n\n\n\nNext we need to associate physical parts to the parts in the schematic. This is done by assigning footprints to schematic symbols. <\/p>\n\n\n\n
<\/a><\/figure><\/div>\n\n\n\nA new window pops-up. Most symbols are already assigned a footprint. For those that are empty you need to select the correct footprint from the right part of the window. On the left part of the window you can select specific groups of footprints. You can also create your own footprints with the footprint-editor and place them in a container of your own.<\/p>\n\n\n\n
<\/figure><\/div>\n\n\n\nNext step is to generate a netlist. A netlist is the translation of the schematic to the PCB design.<\/p>\n\n\n\n
<\/figure><\/div>\n\n\n\nPress the PCBnew icon ..<\/p>\n\n\n\n
<\/figure><\/div>\n\n\n\n.. and a pop-up window will appear ..<\/p>\n\n\n\n
.. asking if it\u2019s OK to create a new PCB (this pop-up will only appear when there\u2019s not already a PCB design).<\/p>\n\n\n\n
Press [Yes] and an empty design window will open. In this window press the [Netlist] icon and select the [Read Current Netlist] to use the Netlist you created in the previous step and press [Close] to close this pop-up window.<\/p>\n\n\n\n<\/a><\/figure>\n\n\n\n<\/a>Next you\u2019ll see the so called <\/strong>rats nest<\/strong><\/em> of components and wires that connects them. <\/strong><\/figcaption><\/figure>\n\n\n\nThe big challenge is to move all the components to a logical place and connect them with copper traces till all the white lines in the rats nest<\/em> are gone..<\/p>\n\n\n\n<\/a><\/figure>\n\n\n\nTime to lay the copper traces.<\/p>\n\n\n\n<\/a><\/figure>\n\n\n\n<\/a>And then it will look like this in 3D <\/strong><\/figcaption><\/figure>\n\n\n\n\n\n\n\nBasic Electronics<\/strong><\/h2>\n\n\n\nCalculating the series-resistor for a LED<\/h3>\n\n\n\n
For every LED, in order to use it properly, we need to know its Forward Voltage. The Forward Voltage (Vf<\/em>) is the voltage used by the LED when it\u2019s \u201con\u201d. <\/p>\n\n\n\n<\/figure><\/div>\n\n\n\nAs you can see from the image Vf<\/em> depends on the color of the LED. <\/p>\n\n\n\nThe Forward Current (If<\/em>) is the current at which the LED is at its brightest. <\/p>\n\n\n\nAccording to Kirchhoff’s Voltage Law<\/em> (KVL) the voltage used by a circuit, in this case the LED in series with the resistor (R), must be equal to the voltage applied (in the image 5.0 volt). If the (green) LED\u2019s Vf<\/em> is 2.2 volt, the voltage over the resistor must be 5.0 – 2.2 = 2.8 volt. If the max. current is 20mA the value of the resistor must be 2.8 \/ 0.02 = 140 \u03a9.<\/p>\n\n\n\nThat is, 140 \u03a9 for the LED at its brightest but even with much less current, say 10mA, the LED will be bright enough. At 10mA the Vf<\/em> is 2 volt which results in a resistor of 3 \/ 0.01 = 300 \u03a9.<\/p>\n\n\n\nAs a rule of thumb a 220 \u03a9 resistor is suitable for all red and green LED\u2019s in the range of 3v3 to 5 volt. <\/p>\n\n\n\n
Calculating the series-resistor for the 4N35<\/h3>\n\n\n\n
According to the data-sheet of the 4N35 the Vf<\/em> of the input diode is ~1 volt and If<\/em> is 10mA. As we drive the 4N35 from one of the GPIO-pins of the ESP8266 the applied voltage is 3v3. The voltage over the resistor is 3v3 – 1 = 2.3 volt. This gives a value for the series resistor of 2.3 \/ 0.01 = 230 \u03a9.<\/p>\n\n\n\nThe VS1838<\/h3>\n\n\n\n
This component is called a IR-detector diode but it is far more than only a diode. It has all the circuitry to detect a modulated IR signal and convert the IR signal into a logic output.<\/p>\n\n\n\n Block diagram VS1838 <\/strong><\/figcaption><\/figure>\n","protected":false},"excerpt":{"rendered":"[ ] In this post I will guide you through the process of building a device that can capture Infrared-messages from an Infrared remote controller (learning mode), and resend the captured Infrared-messages (sending mode). I will use the affordable and … Continue reading
The obvious choice to interface with the device is by using a webserver and restAPI and consequently the device needs an internet connection. The ESP8266 with its builtin WiFi and flash filesystem storage is the logical processor for this project.<\/p>\n\n\n\n
Project setup<\/strong><\/h2>\n\n\n\nThe best way to develop any project is by slicing it into small, logical parts and developing and testing these parts one at the time<\/em>. For now I see three major parts:<\/p>\n\n\n\n- The IR-receiver circuit<\/li>
- The IR-sender circuit<\/li>
- The software to glue everything together<\/li><\/ol>\n\n\n\n
The development will be done with the 1of!-boards<\/a><\/em><\/strong> as they are cheap and easy to use. For the initial setup the 1of!-Wemos<\/a><\/em><\/strong> processor board is the board of choice as it is easily programmed with a USB cable and for the rest of the circuity a 1of!-Solderless bread board<\/em><\/strong> is used. If I\u2019m satisfied with the circuit on the 1of!-Solderless board<\/em><\/strong> I will flash the firmware to a 1of!-ESP12<\/a><\/em><\/strong> <\/a>processor board and build the circuitry on a 1of!-Proto<\/a><\/em><\/strong> board.<\/p>\n\n\n\nThe IR signal processing is handled by a fantastic library<\/a> [v2.6.2 (20190616)] written by Ken Shirriff, David Conran<\/em> and others. For additional details on how the library works, see Ken Shirriff’s blog: A Multi-Protocol Infrared remote Library for the Arduino<\/a>.<\/p>\n\n\n\n\n\n\n\nThe IR-receiver circuit<\/strong><\/h2>\n\n\n\nFor receiving IR-codes an IR-receiver-diode is used. I chose the VS1838B<\/a> which is a commonly used and available part that detects 950nm light at 38kHz.The VS1838B detects the 38kHz modulated IR-message and outputs a logic-pulse.<\/p>\n\n\n\nThe VS1838B detects the 38kHz modulated IR-message and outputs a logic-pulse.<\/p>\n\n\n\n
The IR receiver schematic <\/strong><\/figcaption><\/figure><\/div>\n\n\n\nThe output of the VS1838B is send to GPIO12 of the ESP8266 that will analyse and decode and eventually store the IR-message to a file. <\/p>\n\n\n\n
On the 1of!-Solderless<\/em><\/strong> board it looks like this. (mind you: The final design uses IO-14 for the green LED):<\/p>\n\n\n\n<\/figure><\/div>\n\n\n\nA green LED (D6) is connected to GPIO14 to give some visual indication the device is waiting for an IR-message to capture.<\/p>\n\n\n\n
You can find a program (IR_receiver<\/a>) to test this setup on github<\/a>.<\/p>\n\n\n\nCompile and flash the IR-receiver sketch to the 1of!-Wemos<\/em><\/strong> (or 1of!-ESP12<\/em><\/strong>) board and open the Serial Monitor.<\/p>\n\n\n\n IR_receiver is now running and waiting for IR input on Pin 12\n \n SPIFFS Mount successful\n \n Commands are:\n \n *D - remove file from SPIFFS\n L - List SPIFFS\n H - Help (this message)\n W - Write rawData to SPIFFS\n S - System Status\n *R - Reboot\n \n Timestamp : 000030.031\n Encoding : NEC\n Code : FFA857 (32 bits)\n Library : v2.6.2\n \n Raw Timing[71]:\n + 9342, - 4392, + 684, - 462, + 658, - 488,\n + 716, - 430, + 656, - 488, + 598, - 546,\n + 684, - 460, + 716, - 428, \n . . . .\n + 658, - 1624, + 660, - 486, + 714, - 1568,\n + 744, - 1516, + 708, - 1594, + 718, - 39748,\n + 9346, - 2124, + 708\n \n uint16_t rawData[71] = {9342, 4392, 684, 462, 658, 488, 716,\n 430, 656, 488, 598, 546, 684, 460, 716, 428, 716, 428, 714,\n 1568, 686, 1596, 688, 1592, 658, 1624, 658, 1602, 738,\n 1564, 664, 1618, \n . . . \n 460, 658, 1624, 660, 486, 714, 1568, 744, 1516, 708, 1594,\n 718, 39748, 9346, 2124, 708}; \/\/ NEC FFA857\n uint32_t address = 0x0;\n uint32_t command = 0x15;\n uint64_t data = 0xFFA857;\n \n [Enter: \u2018w\u2019]\n Write rawData to SPIFFS\n save pulses as: [Enter: \u2018demo3\u2019]\n save pulses as [\/pls\/demo3.pls] (y\/N) [Enter: \u2018y\u2019]\n fileName is [\/pls\/demo3.pls]\n writeRawData(\/pls\/demo3.pls): number of pulses [71]\n 9342, 4392, 684, 462, 658, 488, 716, 430, 656, 488, 598, 546,\n 684, 460, 716, 428, 716, 428, 686, 460, 690, 1590, 688, 458, 688, \n 456, 688, 438, 680, 484, 660, 1622, 684, 460, 658,\n . . . \n 714, 1568, 744, 1516, 708, 1594, 718, 39748, 9346, 2124, 708, \n writeRawData(): saved [71] pulses\n \n [Enter \u2018L\u2019]\n \/pls\/pulse1.pls \/ 286\n \/pls\/demo1.pls \/ 306\n \/pls\/demo3.pls \/ 306 <\/pre>\n\n\n\nThe IR-sender circuit<\/strong><\/h2>\n\n\n\nTo be able to send IR-messages we need one or more IR LED<\/a>\u2019s. Using an IR LED is no different from using a \u201cnormal\u201d LED, except for the fact that to get some reach the IR LED\u2019s need far more current to do their job. Since the GPIO-pins of the ESP8266 are not capable of providing these high currents we need a driver circuit. Easiest is to use an opto-coupler like the 4N35 or 4N25 which doubles as a level-shifter from 3v3 (GPIO04) and 5 Volt to drive the Gate of the MOSFET switch.<\/p>\n\n\n\nThe voltage drop over the IR LED is ~1.6Volt and the maximum current is 60mA. As we are using two IR LED\u2019s in parallel and the duty cycle is 50%, the maximum current through R7 is 60*2*2=240mA. Therefor the value of R7 is (5-1.6)\/240 => ~15 Ohm. <\/p>\n\n\n\n
The IR Sender circuit<\/strong><\/figcaption><\/figure><\/div>\n\n\n\nThe pulses come from GPIO04. If GPIO04 is \u201chigh\u201d the led in the optocoupler will ignite and, in turn, sets the transistor to conduct (Pulls the Emitter to 5 Volt). The 5 volt on the Emitter makes the Gate of Q1 \u201chigh\u201d and the MOSFET now also conducts pulling the Drain to ground and so powering the two IR-LED\u2019s (switching them \u201con\u201d).<\/p>\n\n\n\n
A \u201clow\u201d on GPIO04 switches the led in the optocoupler \u201coff\u201d. The transistor opens (no current flows from Collector to Emitter) and R11 pulls the Gate of Q1 to ground. The MOSFET now also does not conduct and no current will flow true the IR-LED\u2019s (switching them \u201coff\u201d).<\/p>\n\n\n\n
This is how it looks on the <\/strong>1of!-Solderless<\/strong><\/em> board <\/strong><\/figcaption><\/figure><\/div>\n\n\n\nMind you: in stead of an IR LED a normal LED is used for testing and therefor the 10 ohm resister (R7) must be 220 ohm!<\/p>\n\n\n\n
You can find a program (IR_sender<\/a>) to test this setup on github<\/a>.<\/p>\n\n\n\nCompile and flash the IR-sender sketch to the 1of!-Wemos<\/em><\/strong> (or 1of!-ESP12<\/em><\/strong>) board and open the Serial Monitor.<\/p>\n\n\n\n \n \n IR_sender is now running and sending IR on pin 4\n \n SPIFFS Mount successful\n \n Commands are:\n \n *D - remove file from SPIFFS\n L - List SPIFFS\n H - Help (this message)\n T - Transmit rawData from SPIFFS\n *R - Reboot\n \n [Enter: \u2018L\u2019]\n [01] [\/pls\/pulse5.pls]\n [02] [\/pls\/pulse1.pls]\n [03] [\/pls\/mutsiCool26.pls]\n [04] [\/pls\/demo1.pls]\n [05] [\/pls\/demo3.pls]\n \n [Enter: \u2018t\u2019]\n Transmit rawData from SPIFFS\n \n Pulse file number: [Enter: \u20183\u2019]\n \n fileName is [\/pls\/mutsiCool26.pls]\n readRawData(\/pls\/mutsiCool26.pls): \n readRawData(): read [307] pulses\n \n\n Sending [307] pulses .. (redled blinks) <\/pre>\n\n\n\nAs the basics are working we can solder the IR-sender and IR-receiver circuitry\u2019s to a 1of!-Proto<\/em><\/strong> board. <\/p>\n\n\n\n First the signal LED\u2019s <\/strong><\/figcaption><\/figure><\/div>\n\n\n\nAfter confirming the signal-LED\u2019s blink solder the rest of the circuit:<\/p>\n\n\n\n
<\/figure><\/div>\n\n\n\nI must say, the range of the IR-sender circuit is not as good as I expected. Why is my TV-remote capable of switching channels by pointing it to the opposite wall and does my IR-sender needs to be pointed exactly to my TV? So I reversed engineered two of my remotes and was surprised that they use (almost) the same circuit to drive the IR-LED’s only they have both left out the serie resister<\/em> (R7)!! As I do not want to blow my IR-LED’s I have reduced R7 to only 1 ohm and that enlarged the range quite a bit!<\/p>\n\n\n\n\n\n\n\nThe Firmware to glue everything together<\/strong><\/h2>\n\n\n\nThe firmware uses Web Sockets to interface with the browser. When accessing the URL of the device a simple index.html page is loaded. This page uses Javascript to setup the WebSocket communication between the IR IoT Remote<\/strong><\/em> and the browser.<\/p>\n\n\n\nMain Control Window<\/figcaption><\/figure><\/div>\n\n\n\nThe firmware is still ‘Work in Progress<\/em>‘!<\/p>\n\n\n\nLearn Window<\/figcaption><\/figure><\/div>\n\n\n\nEdit Labels and Order<\/figcaption><\/figure><\/div>\n\n\n\nFS explorer<\/figcaption><\/figure><\/div>\n\n\n\nYou can find the firmware (IR_IoT_Remote) on github<\/a>.<\/p>\n\n\n\nFuture Extentions<\/strong><\/h2>\n\n\n\nExternal Keyboard<\/h3>\n\n\n\n
For some people a web interface is not ideal. For those I added a keyboard interface (J7) that communicates with a keyboard like this<\/a>. The output is a voltage depending on the key pressed. The ADC pin of the ESP-12 can analyse this voltage to decide which key is pressed and send an IR-command depending on that key.<\/p>\n\n\n\nMind you, the firmware has no function for this. You have to make it yourself.<\/em><\/p>\n\n\n\nTemperature Sensor<\/h3>\n\n\n\n
It is fairly simple to implement an interface for a DS18B20 one-wire temperature sensor. You can connect a DS18B20 via port J5.<\/p>\n\n\n\n\n\n\n\n
Making the One of a Kind version<\/strong><\/h2>\n\n\n\nNow everything is in place most of the work for making an One of a Kind<\/em><\/strong> device is done. Whats left is placing the 1of!-Processor<\/em><\/strong> and 1of!-Proto<\/em><\/strong> boards in a project box like this<\/a> one or this<\/a> one. <\/p>\n\n\n\n<\/figure><\/li><\/figure><\/li><\/ul><\/figure>\n\n\n\nIt makes a neat enclosure with the (IR) LED\u2019s on one end and an USB power connector at the other end. Of course I have swapped the 1of!-Wemos<\/em><\/strong> board for a 1of!-ESP12<\/em><\/strong>.<\/p>\n\n\n\nMaking a Printed Circuit Board (PCB)<\/strong><\/h2>\n\n\n\nThis is not a comprehensive guide on how to use KiCAD as there are tons of posts on the web and dozens of good books<\/a> for that. I just want to show you the steps involved in the hope you will give it a try! Although KiCAD has a very steep learning curve, for me it is one of the best tools you can use for designing your own PCB\u2019s.<\/p>\n\n\n\nTo be able to design a PCB for this device we need to combine the schematics of the 1of!-ESP12<\/em><\/strong> processor board and the schematic of the IR-receiver and IR-sender.<\/p>\n\n\n\nIn KiCAD you can import an existing schematic sheet into the schematic you are working on.<\/p>\n\n\n\n
So, start with a new, empty sheet. In the File-menu select [Append Schematic Sheet]<\/p>\n\n\n\n
<\/figure><\/div>\n\n\n\nThen select the 1of!-ESP12.sch<\/a> file (it\u2019s in the map KiCad<\/em> on the github<\/a> repository).<\/p>\n\n\n\n<\/figure><\/div>\n\n\n\nRemove the 20-pin connector. Select the remaining objects and move them outside the sheet.<\/p>\n\n\n\n
Now again select [Append Schematic Sheet] from the File-menu and select the Schematic for the IR-receiver and sender<\/a> (you can find it in the map KiCad<\/em> on the github<\/a> repository).<\/p>\n\n\n\nRemove the connector and move everything around till you have something like this:<\/p>\n\n\n\n<\/a><\/figure>\n\n\n\n<\/figure><\/div>\n\n\n\nAll field references have a question mark (?) so you need to press the annotate button.<\/p>\n\n\n\n
After that all fields have a unique reference. Don’t worry, if your references are different from the ones in this post!<\/p>\n\n\n\n
<\/figure><\/div>\n\n\n\nNext we need to associate physical parts to the parts in the schematic. This is done by assigning footprints to schematic symbols. <\/p>\n\n\n\n
<\/a><\/figure><\/div>\n\n\n\nA new window pops-up. Most symbols are already assigned a footprint. For those that are empty you need to select the correct footprint from the right part of the window. On the left part of the window you can select specific groups of footprints. You can also create your own footprints with the footprint-editor and place them in a container of your own.<\/p>\n\n\n\n
<\/figure><\/div>\n\n\n\nNext step is to generate a netlist. A netlist is the translation of the schematic to the PCB design.<\/p>\n\n\n\n
<\/figure><\/div>\n\n\n\nPress the PCBnew icon ..<\/p>\n\n\n\n
<\/figure><\/div>\n\n\n\n.. and a pop-up window will appear ..<\/p>\n\n\n\n
.. asking if it\u2019s OK to create a new PCB (this pop-up will only appear when there\u2019s not already a PCB design).<\/p>\n\n\n\n
Press [Yes] and an empty design window will open. In this window press the [Netlist] icon and select the [Read Current Netlist] to use the Netlist you created in the previous step and press [Close] to close this pop-up window.<\/p>\n\n\n\n<\/a><\/figure>\n\n\n\n<\/a>Next you\u2019ll see the so called <\/strong>rats nest<\/strong><\/em> of components and wires that connects them. <\/strong><\/figcaption><\/figure>\n\n\n\nThe big challenge is to move all the components to a logical place and connect them with copper traces till all the white lines in the rats nest<\/em> are gone..<\/p>\n\n\n\n<\/a><\/figure>\n\n\n\nTime to lay the copper traces.<\/p>\n\n\n\n<\/a><\/figure>\n\n\n\n<\/a>And then it will look like this in 3D <\/strong><\/figcaption><\/figure>\n\n\n\n\n\n\n\nBasic Electronics<\/strong><\/h2>\n\n\n\nCalculating the series-resistor for a LED<\/h3>\n\n\n\n
For every LED, in order to use it properly, we need to know its Forward Voltage. The Forward Voltage (Vf<\/em>) is the voltage used by the LED when it\u2019s \u201con\u201d. <\/p>\n\n\n\n<\/figure><\/div>\n\n\n\nAs you can see from the image Vf<\/em> depends on the color of the LED. <\/p>\n\n\n\nThe Forward Current (If<\/em>) is the current at which the LED is at its brightest. <\/p>\n\n\n\nAccording to Kirchhoff’s Voltage Law<\/em> (KVL) the voltage used by a circuit, in this case the LED in series with the resistor (R), must be equal to the voltage applied (in the image 5.0 volt). If the (green) LED\u2019s Vf<\/em> is 2.2 volt, the voltage over the resistor must be 5.0 – 2.2 = 2.8 volt. If the max. current is 20mA the value of the resistor must be 2.8 \/ 0.02 = 140 \u03a9.<\/p>\n\n\n\nThat is, 140 \u03a9 for the LED at its brightest but even with much less current, say 10mA, the LED will be bright enough. At 10mA the Vf<\/em> is 2 volt which results in a resistor of 3 \/ 0.01 = 300 \u03a9.<\/p>\n\n\n\nAs a rule of thumb a 220 \u03a9 resistor is suitable for all red and green LED\u2019s in the range of 3v3 to 5 volt. <\/p>\n\n\n\n
Calculating the series-resistor for the 4N35<\/h3>\n\n\n\n
According to the data-sheet of the 4N35 the Vf<\/em> of the input diode is ~1 volt and If<\/em> is 10mA. As we drive the 4N35 from one of the GPIO-pins of the ESP8266 the applied voltage is 3v3. The voltage over the resistor is 3v3 – 1 = 2.3 volt. This gives a value for the series resistor of 2.3 \/ 0.01 = 230 \u03a9.<\/p>\n\n\n\nThe VS1838<\/h3>\n\n\n\n
This component is called a IR-detector diode but it is far more than only a diode. It has all the circuitry to detect a modulated IR signal and convert the IR signal into a logic output.<\/p>\n\n\n\n Block diagram VS1838 <\/strong><\/figcaption><\/figure>\n","protected":false},"excerpt":{"rendered":"[ ] In this post I will guide you through the process of building a device that can capture Infrared-messages from an Infrared remote controller (learning mode), and resend the captured Infrared-messages (sending mode). I will use the affordable and … Continue reading
- The IR-receiver circuit<\/li>
- The IR-sender circuit<\/li>
- The software to glue everything together<\/li><\/ol>\n\n\n\n
The development will be done with the 1of!-boards<\/a><\/em><\/strong> as they are cheap and easy to use. For the initial setup the 1of!-Wemos<\/a><\/em><\/strong> processor board is the board of choice as it is easily programmed with a USB cable and for the rest of the circuity a 1of!-Solderless bread board<\/em><\/strong> is used. If I\u2019m satisfied with the circuit on the 1of!-Solderless board<\/em><\/strong> I will flash the firmware to a 1of!-ESP12<\/a><\/em><\/strong> <\/a>processor board and build the circuitry on a 1of!-Proto<\/a><\/em><\/strong> board.<\/p>\n\n\n\n
The IR signal processing is handled by a fantastic library<\/a> [v2.6.2 (20190616)] written by Ken Shirriff, David Conran<\/em> and others. For additional details on how the library works, see Ken Shirriff’s blog: A Multi-Protocol Infrared remote Library for the Arduino<\/a>.<\/p>\n\n\n\n\n\n\n\n
The IR-receiver circuit<\/strong><\/h2>\n\n\n\n
For receiving IR-codes an IR-receiver-diode is used. I chose the VS1838B<\/a> which is a commonly used and available part that detects 950nm light at 38kHz.The VS1838B detects the 38kHz modulated IR-message and outputs a logic-pulse.<\/p>\n\n\n\n
The VS1838B detects the 38kHz modulated IR-message and outputs a logic-pulse.<\/p>\n\n\n\n
The IR receiver schematic <\/strong><\/figcaption><\/figure><\/div>\n\n\n\nThe output of the VS1838B is send to GPIO12 of the ESP8266 that will analyse and decode and eventually store the IR-message to a file. <\/p>\n\n\n\n
On the 1of!-Solderless<\/em><\/strong> board it looks like this. (mind you: The final design uses IO-14 for the green LED):<\/p>\n\n\n\n
<\/figure><\/div>\n\n\n\nA green LED (D6) is connected to GPIO14 to give some visual indication the device is waiting for an IR-message to capture.<\/p>\n\n\n\n
You can find a program (IR_receiver<\/a>) to test this setup on github<\/a>.<\/p>\n\n\n\n
Compile and flash the IR-receiver sketch to the 1of!-Wemos<\/em><\/strong> (or 1of!-ESP12<\/em><\/strong>) board and open the Serial Monitor.<\/p>\n\n\n\n
IR_receiver is now running and waiting for IR input on Pin 12\n \n SPIFFS Mount successful\n \n Commands are:\n \n *D - remove file from SPIFFS\n L - List SPIFFS\n H - Help (this message)\n W - Write rawData to SPIFFS\n S - System Status\n *R - Reboot\n \n Timestamp : 000030.031\n Encoding : NEC\n Code : FFA857 (32 bits)\n Library : v2.6.2\n \n Raw Timing[71]:\n + 9342, - 4392, + 684, - 462, + 658, - 488,\n + 716, - 430, + 656, - 488, + 598, - 546,\n + 684, - 460, + 716, - 428, \n . . . .\n + 658, - 1624, + 660, - 486, + 714, - 1568,\n + 744, - 1516, + 708, - 1594, + 718, - 39748,\n + 9346, - 2124, + 708\n \n uint16_t rawData[71] = {9342, 4392, 684, 462, 658, 488, 716,\n 430, 656, 488, 598, 546, 684, 460, 716, 428, 716, 428, 714,\n 1568, 686, 1596, 688, 1592, 658, 1624, 658, 1602, 738,\n 1564, 664, 1618, \n . . . \n 460, 658, 1624, 660, 486, 714, 1568, 744, 1516, 708, 1594,\n 718, 39748, 9346, 2124, 708}; \/\/ NEC FFA857\n uint32_t address = 0x0;\n uint32_t command = 0x15;\n uint64_t data = 0xFFA857;\n \n [Enter: \u2018w\u2019]\n Write rawData to SPIFFS\n save pulses as: [Enter: \u2018demo3\u2019]\n save pulses as [\/pls\/demo3.pls] (y\/N) [Enter: \u2018y\u2019]\n fileName is [\/pls\/demo3.pls]\n writeRawData(\/pls\/demo3.pls): number of pulses [71]\n 9342, 4392, 684, 462, 658, 488, 716, 430, 656, 488, 598, 546,\n 684, 460, 716, 428, 716, 428, 686, 460, 690, 1590, 688, 458, 688, \n 456, 688, 438, 680, 484, 660, 1622, 684, 460, 658,\n . . . \n 714, 1568, 744, 1516, 708, 1594, 718, 39748, 9346, 2124, 708, \n writeRawData(): saved [71] pulses\n \n [Enter \u2018L\u2019]\n \/pls\/pulse1.pls \/ 286\n \/pls\/demo1.pls \/ 306\n \/pls\/demo3.pls \/ 306 <\/pre>\n\n\n\nThe IR-sender circuit<\/strong><\/h2>\n\n\n\n
To be able to send IR-messages we need one or more IR LED<\/a>\u2019s. Using an IR LED is no different from using a \u201cnormal\u201d LED, except for the fact that to get some reach the IR LED\u2019s need far more current to do their job. Since the GPIO-pins of the ESP8266 are not capable of providing these high currents we need a driver circuit. Easiest is to use an opto-coupler like the 4N35 or 4N25 which doubles as a level-shifter from 3v3 (GPIO04) and 5 Volt to drive the Gate of the MOSFET switch.<\/p>\n\n\n\n
The voltage drop over the IR LED is ~1.6Volt and the maximum current is 60mA. As we are using two IR LED\u2019s in parallel and the duty cycle is 50%, the maximum current through R7 is 60*2*2=240mA. Therefor the value of R7 is (5-1.6)\/240 => ~15 Ohm. <\/p>\n\n\n\n
The IR Sender circuit<\/strong><\/figcaption><\/figure><\/div>\n\n\n\n The pulses come from GPIO04. If GPIO04 is \u201chigh\u201d the led in the optocoupler will ignite and, in turn, sets the transistor to conduct (Pulls the Emitter to 5 Volt). The 5 volt on the Emitter makes the Gate of Q1 \u201chigh\u201d and the MOSFET now also conducts pulling the Drain to ground and so powering the two IR-LED\u2019s (switching them \u201con\u201d).<\/p>\n\n\n\n
A \u201clow\u201d on GPIO04 switches the led in the optocoupler \u201coff\u201d. The transistor opens (no current flows from Collector to Emitter) and R11 pulls the Gate of Q1 to ground. The MOSFET now also does not conduct and no current will flow true the IR-LED\u2019s (switching them \u201coff\u201d).<\/p>\n\n\n\n
This is how it looks on the <\/strong>1of!-Solderless<\/strong><\/em> board <\/strong><\/figcaption><\/figure><\/div>\n\n\n\n Mind you: in stead of an IR LED a normal LED is used for testing and therefor the 10 ohm resister (R7) must be 220 ohm!<\/p>\n\n\n\n
You can find a program (IR_sender<\/a>) to test this setup on github<\/a>.<\/p>\n\n\n\n
Compile and flash the IR-sender sketch to the 1of!-Wemos<\/em><\/strong> (or 1of!-ESP12<\/em><\/strong>) board and open the Serial Monitor.<\/p>\n\n\n\n
\n \n IR_sender is now running and sending IR on pin 4\n \n SPIFFS Mount successful\n \n Commands are:\n \n *D - remove file from SPIFFS\n L - List SPIFFS\n H - Help (this message)\n T - Transmit rawData from SPIFFS\n *R - Reboot\n \n [Enter: \u2018L\u2019]\n [01] [\/pls\/pulse5.pls]\n [02] [\/pls\/pulse1.pls]\n [03] [\/pls\/mutsiCool26.pls]\n [04] [\/pls\/demo1.pls]\n [05] [\/pls\/demo3.pls]\n \n [Enter: \u2018t\u2019]\n Transmit rawData from SPIFFS\n \n Pulse file number: [Enter: \u20183\u2019]\n \n fileName is [\/pls\/mutsiCool26.pls]\n readRawData(\/pls\/mutsiCool26.pls): \n readRawData(): read [307] pulses\n \n\n Sending [307] pulses .. (redled blinks) <\/pre>\n\n\n\n
As the basics are working we can solder the IR-sender and IR-receiver circuitry\u2019s to a 1of!-Proto<\/em><\/strong> board. <\/p>\n\n\n\n
First the signal LED\u2019s <\/strong><\/figcaption><\/figure><\/div>\n\n\n\n After confirming the signal-LED\u2019s blink solder the rest of the circuit:<\/p>\n\n\n\n
<\/figure><\/div>\n\n\n\nI must say, the range of the IR-sender circuit is not as good as I expected. Why is my TV-remote capable of switching channels by pointing it to the opposite wall and does my IR-sender needs to be pointed exactly to my TV? So I reversed engineered two of my remotes and was surprised that they use (almost) the same circuit to drive the IR-LED’s only they have both left out the serie resister<\/em> (R7)!! As I do not want to blow my IR-LED’s I have reduced R7 to only 1 ohm and that enlarged the range quite a bit!<\/p>\n\n\n\n\n\n\n\n
The Firmware to glue everything together<\/strong><\/h2>\n\n\n\n
The firmware uses Web Sockets to interface with the browser. When accessing the URL of the device a simple index.html page is loaded. This page uses Javascript to setup the WebSocket communication between the IR IoT Remote<\/strong><\/em> and the browser.<\/p>\n\n\n\n
Main Control Window<\/figcaption><\/figure><\/div>\n\n\n\n The firmware is still ‘Work in Progress<\/em>‘!<\/p>\n\n\n\n
Learn Window<\/figcaption><\/figure><\/div>\n\n\n\n Edit Labels and Order<\/figcaption><\/figure><\/div>\n\n\n\n FS explorer<\/figcaption><\/figure><\/div>\n\n\n\n You can find the firmware (IR_IoT_Remote) on github<\/a>.<\/p>\n\n\n\n
Future Extentions<\/strong><\/h2>\n\n\n\n
External Keyboard<\/h3>\n\n\n\n
For some people a web interface is not ideal. For those I added a keyboard interface (J7) that communicates with a keyboard like this<\/a>. The output is a voltage depending on the key pressed. The ADC pin of the ESP-12 can analyse this voltage to decide which key is pressed and send an IR-command depending on that key.<\/p>\n\n\n\n
Mind you, the firmware has no function for this. You have to make it yourself.<\/em><\/p>\n\n\n\n
Temperature Sensor<\/h3>\n\n\n\n
It is fairly simple to implement an interface for a DS18B20 one-wire temperature sensor. You can connect a DS18B20 via port J5.<\/p>\n\n\n\n\n\n\n\n
Making the One of a Kind version<\/strong><\/h2>\n\n\n\n
Now everything is in place most of the work for making an One of a Kind<\/em><\/strong> device is done. Whats left is placing the 1of!-Processor<\/em><\/strong> and 1of!-Proto<\/em><\/strong> boards in a project box like this<\/a> one or this<\/a> one. <\/p>\n\n\n\n
- <\/figure><\/li><\/figure><\/li><\/ul><\/figure>\n\n\n\n
It makes a neat enclosure with the (IR) LED\u2019s on one end and an USB power connector at the other end. Of course I have swapped the 1of!-Wemos<\/em><\/strong> board for a 1of!-ESP12<\/em><\/strong>.<\/p>\n\n\n\n
Making a Printed Circuit Board (PCB)<\/strong><\/h2>\n\n\n\n
This is not a comprehensive guide on how to use KiCAD as there are tons of posts on the web and dozens of good books<\/a> for that. I just want to show you the steps involved in the hope you will give it a try! Although KiCAD has a very steep learning curve, for me it is one of the best tools you can use for designing your own PCB\u2019s.<\/p>\n\n\n\n
To be able to design a PCB for this device we need to combine the schematics of the 1of!-ESP12<\/em><\/strong> processor board and the schematic of the IR-receiver and IR-sender.<\/p>\n\n\n\n
In KiCAD you can import an existing schematic sheet into the schematic you are working on.<\/p>\n\n\n\n
So, start with a new, empty sheet. In the File-menu select [Append Schematic Sheet]<\/p>\n\n\n\n
<\/figure><\/div>\n\n\n\nThen select the 1of!-ESP12.sch<\/a> file (it\u2019s in the map KiCad<\/em> on the github<\/a> repository).<\/p>\n\n\n\n
<\/figure><\/div>\n\n\n\nRemove the 20-pin connector. Select the remaining objects and move them outside the sheet.<\/p>\n\n\n\n
Now again select [Append Schematic Sheet] from the File-menu and select the Schematic for the IR-receiver and sender<\/a> (you can find it in the map KiCad<\/em> on the github<\/a> repository).<\/p>\n\n\n\n
Remove the connector and move everything around till you have something like this:<\/p>\n\n\n\n
<\/a><\/figure>\n\n\n\n<\/figure><\/div>\n\n\n\nAll field references have a question mark (?) so you need to press the annotate button.<\/p>\n\n\n\n
After that all fields have a unique reference. Don’t worry, if your references are different from the ones in this post!<\/p>\n\n\n\n
<\/figure><\/div>\n\n\n\nNext we need to associate physical parts to the parts in the schematic. This is done by assigning footprints to schematic symbols. <\/p>\n\n\n\n
<\/a><\/figure><\/div>\n\n\n\nA new window pops-up. Most symbols are already assigned a footprint. For those that are empty you need to select the correct footprint from the right part of the window. On the left part of the window you can select specific groups of footprints. You can also create your own footprints with the footprint-editor and place them in a container of your own.<\/p>\n\n\n\n
<\/figure><\/div>\n\n\n\nNext step is to generate a netlist. A netlist is the translation of the schematic to the PCB design.<\/p>\n\n\n\n
<\/figure><\/div>\n\n\n\nPress the PCBnew icon ..<\/p>\n\n\n\n
<\/figure><\/div>\n\n\n\n.. and a pop-up window will appear ..<\/p>\n\n\n\n
.. asking if it\u2019s OK to create a new PCB (this pop-up will only appear when there\u2019s not already a PCB design).<\/p>\n\n\n\n
Press [Yes] and an empty design window will open. In this window press the [Netlist] icon and select the [Read Current Netlist] to use the Netlist you created in the previous step and press [Close] to close this pop-up window.<\/p>\n\n\n\n
<\/a><\/figure>\n\n\n\n<\/a>Next you\u2019ll see the so called <\/strong>rats nest<\/strong><\/em> of components and wires that connects them. <\/strong><\/figcaption><\/figure>\n\n\n\n The big challenge is to move all the components to a logical place and connect them with copper traces till all the white lines in the rats nest<\/em> are gone..<\/p>\n\n\n\n
<\/a><\/figure>\n\n\n\nTime to lay the copper traces.<\/p>\n\n\n\n
<\/a><\/figure>\n\n\n\n<\/a>And then it will look like this in 3D <\/strong><\/figcaption><\/figure>\n\n\n\n\n\n\n\n Basic Electronics<\/strong><\/h2>\n\n\n\n
Calculating the series-resistor for a LED<\/h3>\n\n\n\n
For every LED, in order to use it properly, we need to know its Forward Voltage. The Forward Voltage (Vf<\/em>) is the voltage used by the LED when it\u2019s \u201con\u201d. <\/p>\n\n\n\n
<\/figure><\/div>\n\n\n\nAs you can see from the image Vf<\/em> depends on the color of the LED. <\/p>\n\n\n\n
The Forward Current (If<\/em>) is the current at which the LED is at its brightest. <\/p>\n\n\n\n
According to Kirchhoff’s Voltage Law<\/em> (KVL) the voltage used by a circuit, in this case the LED in series with the resistor (R), must be equal to the voltage applied (in the image 5.0 volt). If the (green) LED\u2019s Vf<\/em> is 2.2 volt, the voltage over the resistor must be 5.0 – 2.2 = 2.8 volt. If the max. current is 20mA the value of the resistor must be 2.8 \/ 0.02 = 140 \u03a9.<\/p>\n\n\n\n
That is, 140 \u03a9 for the LED at its brightest but even with much less current, say 10mA, the LED will be bright enough. At 10mA the Vf<\/em> is 2 volt which results in a resistor of 3 \/ 0.01 = 300 \u03a9.<\/p>\n\n\n\n
As a rule of thumb a 220 \u03a9 resistor is suitable for all red and green LED\u2019s in the range of 3v3 to 5 volt. <\/p>\n\n\n\n
Calculating the series-resistor for the 4N35<\/h3>\n\n\n\n
According to the data-sheet of the 4N35 the Vf<\/em> of the input diode is ~1 volt and If<\/em> is 10mA. As we drive the 4N35 from one of the GPIO-pins of the ESP8266 the applied voltage is 3v3. The voltage over the resistor is 3v3 – 1 = 2.3 volt. This gives a value for the series resistor of 2.3 \/ 0.01 = 230 \u03a9.<\/p>\n\n\n\n
The VS1838<\/h3>\n\n\n\n
This component is called a IR-detector diode but it is far more than only a diode. It has all the circuitry to detect a modulated IR signal and convert the IR signal into a logic output.<\/p>\n\n\n\n
Block diagram VS1838 <\/strong><\/figcaption><\/figure>\n","protected":false},"excerpt":{"rendered":" [ ] In this post I will guide you through the process of building a device that can capture Infrared-messages from an Infrared remote controller (learning mode), and resend the captured Infrared-messages (sending mode). I will use the affordable and … Continue reading