espwol: A ESP Based WiFi WoL (technically not) solution

This design is still a working progress, although it's already up and running in my PC 👍 it's been great

Contents

• espwol: A ESP Based WiFi WoL(technically not) solution
  • Contents
  • What is espwol?
  • Usage
    • Through POSTMAN
    • Through cURL
  • Hardware Design
    • List of Components
    • Schematics
    • Wireing
  • Software
  • Contributing and TODO

What is espwol?

I wanted to connect to my home PC from work, which already has Windows RDC setup and forwarded. However, I always find myself in the situation of forgetting to power on my PC before I leave.

WoL(Wake on LAN) is definitely a valid solution, I just need to send a magic packet to my PC to turn it on but the issue is I do not have a Ethernet connection to my PC, and WoL is almost impossible to do with WiFi cards.

Instead of using the WoL feature of my motherboard, espwol uses a WiFi connected ESP8266 NodeMCU to received post requests and activates a solid state relay(Optocoupler) to short the power button, just like how you would power on a PC at home.

Usage

To create the push request through the internet, you could assign a static ip for the ESP through your router and port forward the http port 80 to the internet.

However, this is not recommended if you do not have authentication set up, which is what is in place now.

What I do is I connect through my server that has Open VPN setup with proper authentication and then I can send a post request to e.g.192.168.0.100 just like I'm at home.

Through POSTMAN

I like to use POSTMAN to test my API's and its a easy way to send requests.

Through cURL

curl -X POST http://192.168.0.100/push

Hardware Design

The hardware of the solution is fairly simple consisting of only 3 components, of course, you need your jumpers, perf-boards or fancy sockets if you want.

List of Components

• NodeMCU v1.0 (Or any other ESP based chip, for example a ESP32)
• PC817 Optocoupler (4N25, 6N136, MOC3021, MOC3041, 6N137 could all work)
• 150Ω resistor

Schematics

The push button is not needed, its just there to repersent the power button on your PC

Wiring

1. +5V and GND to vin and GND pin on ESP
2. pin 1 of PC817 to 150Ω resistor then D0(aka GPIO16)
3. pin 2 of PC817 to GND
4. connect whatever connector you like for the input and output pins, I just used some standard two screw PCB termination blocks.

We also need two sets of connects from the PC to the ESP

1. Connect GND of power supply to GND of ESP, you can find a GND wire on the 24 pin,PCI-E,SATA or any kind of wire that comes out from your PSU, it's almost always a black one.

2. Connect +5V to the vin of ESP. To do this, you need the always on +5v from your 24 pin connector to the mother board, its the purple wire or pin 9.

3. What I did was simply cut the purple wire on my 24 pin atx connector and spliced in a wire that goes into my ESP. For the grounding, I just used an unused SATA connector.

Software

The software of this design is very simple, I just need a server that connects to my home WiFi and listens to POST requests on a endpoint. Since I will be running this in my local network only, I didn't implement any security features, but definitely a future TODO.

The server is written using aREST by @marcoschwartz which makes it super easy to create a end-point to send requests.

Theres only a couple of lines that I added to the boiler plate code of the library to make it work.

I'm using platform.io through VSCode but you can write the script in ArduinoIDE; however, you you need to install the aREST library regardless.

// Define powerbutton pin
#define POWER_BUTTON_PIN D0

int push(String command)
{
  digitalWrite(POWER_BUTTON_PIN, HIGH);
  Serial.println("Button Pushed...");
  delay(200);
  digitalWrite(POWER_BUTTON_PIN, LOW);
  return 1;
}

void setup(void)
{
...
// Initiate D0 as an output
pinMode(POWER_BUTTON_PIN, OUTPUT);

// Function to be exposed
rest.function("push", push);
...
}

Full Code

Contributing and TODO

Please feel free to create a pull request if you want to add more features, fix a bug or add anything. Here are some ideas that I want to implement:

• Add authentication and security to POST
• Intercept and measure computer power state
• Add another channel for RESET button
• Create a WebUI for managing post Requests and host it through the ESP
• Setup ESP Watchdog to save a bit of power