Different hex code with PS2

Projects Networking, Protocols, and Devices
1

Hi everyone

I tried to connect PS2 cable of keyboard to arduino UNO and get the data from keyboard. I have read many pages on internet and also used different libraries of Arduino. The problem is that non of them cannot detect (read) the "PrtSc" button. Then, I tried to write the code myself. This is the code:

int incomingByte = 0; // for incoming serial data

void setup() {
  Serial.begin(9600); // opens serial port, sets data rate to 9600 bps
}

void loop() {  
  // send data only when you receive data:
  if (Serial.available() > 0) {
    // read the incoming byte:
    incomingByte = Serial.read();
    
    // say what you got:
    Serial.print("I received: ");
    Serial.println(incomingByte, HEX);
  }
 }

The problem is that when I pressed key "1" different times, it gives me different three hex values comparing together. Interestingly, "PrtSc" works correctly and return the same value always.

Any help is appreciated in advance

2

You're not reading from the keyboard, you're reading from the Serial port.
You just have to find the scan code for the PrtScr key, and a library that reads the scan codes from the PS/2 port (all libraries do this under the hood).

Pieter

3

Dear Pieter

Thank you for your reply.

PieterP:
You're not reading from the keyboard, you're reading from the Serial port.

The question is that why it return different valus for one key.

PieterP:
You just have to find the scan code for the PrtScr key, and a library that reads the scan codes from the PS/2 port (all libraries do this under the hood).

Do you mean that I have to find a code that able to scan the code corresponding to each key? Do you have any code?

Thanks

4

Try this library: GitHub - PaulStoffregen/PS2Keyboard: PS/2 Keyboard Library for Arduino
There are examples and documentation available. Instead of keyboard.read(), use keyboard.readScanCode(). If the result is not zero print it to the Serial monitor.