Do you already have the amazing Mele F10 remote and wonder why the Power Button does not work? It is actually designed to work only with the Mele Set-top box but with this IR receiver you can turn not only OFF but also ON almost any HTPC within reach without having to get up from your warm couch!
The circuit is very simple.
Linkit ONE is used as the microcontroller to read the IR code for the power button (0xC9D1F64D) from the IR module HX1838.
If the right code is detected a simple 1ch relay module is activated for a second to send the power off signal to the Motherboard. If at the end of the 1 second the power button is still pressed on the remote and remains pressed for 4 more seconds the relay stays activated for all that time causing a hard reset. That is very useful if you have a problematic HTPC that locks some times and requires to remove the power or press the power hard button for 5 seconds to trigger a forced reboot. All that AFTER you get up from your cosy couch, you couch potato you!
Step 1: The Circuit
The circuit is very simple (attached).
As I couldn't find the symbol for the HX1838 in Fritzing I used a simple IR LED as a placeholder. The pinout is the same but please use the actual board with the 2 resistors for the HX1838 with Vcc, GND and IN pins. IN pin goes to D11 of Linkit.
The schematic shows a simple 5V relay controlled by an NPN transistor. If you decide you use a 1 channel relay module, you don't need R1, Q1 and U1. Connect Linkit's D12 to the relay's input signal.
Switch S1 is the actual switch of the motherboard. Look up the pinout from your motherboard's user manual and connect the relay contacts to the contacts that go to the power switch of your PC.
As the board is powered by 5V use one of the spare on-board USB pin headers to steal that 5V. Make sure from BIOS that power to that pin-header remains on while the motherboad is off (S3 or whatever you choose to sleep to)
Step 2: Load the Code
Load the code to your Linkit ONE and you are ready.
Power up your project from a USB port.
Test by pressing the power button in front of the HX1838.
Watch for that click-click sound of the relay!
If nothing happened enable debugging in serial port by uncommenting
If you get stuck, feel free to ask me here!