benjamin maus

is allesblinkt. he codes, tinkers and designs in berlin at the moment.

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arduino barcode

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Description

This code reads the input from a ps/2 keyboard or keyboard-like device (e.g. a barcode scanner), translates the scan-codes into numbers (only numbers from 0 to 9 can be used at the moment)

It is nowhere near a complete implementation of the ps/2 protocol, but it should give you a starting point.

More info at the Arduino Wiki

Code



int SCAN_ENTER = 0x5a;
int SCAN_BREAK = 0xf0;

int breakActive = 0;

// Clock is only output.
int clockPin = 3;
// The data pin is bi-directional
int dataPin = 2;

// But at the moment we are only interested in receiving
// If a SCAN_ENTER scancode is received the LED blink

int ledPin = 13;

int clockValue = 0;
byte dataValue;

byte scanCodes[10] = {0x45,0x16,0x1e,0x26,0x25,0x2e,0x36,0x3d,0x3e,0x46};
char characters[10] = {'0', '1', '2', '3', '4', '5', '6', '7', '8', '9'};

int quantityCodes = 10;

// This saves the characters (for now only numbers)
char buffer[64] = {};
int bufferPos = 0;
int bufferLength = 64;


void setup() {
pinMode(dataPin, INPUT);
pinMode(clockPin, INPUT);

pinMode(ledPin, OUTPUT);

Serial.begin(9600);
}


void loop() {
dataValue = dataRead();

// If there is a break code, skip the next byte
if (dataValue == SCAN_BREAK) {
breakActive = 1;
}

// Translate the scan codes to numbers
// If there is a match, store it to the buffer
for (int i = 0; i < quantityCodes; i++) {
byte temp = scanCodes[i];

if(temp == dataValue){
if(!breakActive == 1){
buffer[bufferPos] = characters[i];
bufferPos++;
}
}

}


// Print the buffer if SCAN_ENTER is pressed.
if(dataValue == SCAN_ENTER){

Serial.print("\nbuffer: ");

// Read the buffer
int i=0;
if (buffer[i] != 0) {
while(buffer[i] != 0) {
Serial.print( buffer[i] );
buffer[i] = 0;
i++;
}
}

Serial.println(" [Enter]");

bufferPos = 0;

// Blink the LED
digitalWrite(ledPin, HIGH);
delay(300);
digitalWrite(ledPin, LOW);
}

// Reset the SCAN_BREAK state if the byte was a normal one
if(dataValue != SCAN_BREAK){
breakActive = 0;
}

dataValue = 0;
}


int dataRead()
{
byte val = 0;

// Skip start state and start bit
while (digitalRead(clockPin));  // Wait for LOW.
// clock is high when idle
while (!digitalRead(clockPin)); // Wait for HIGH.
while (digitalRead(clockPin));  // Wait for LOW.


for (int offset = 0; offset < 8; offset++) {
while (digitalRead(clockPin));         // Wait for LOW
val |= digitalRead(dataPin) << offset; // Add to byte
while (!digitalRead(clockPin));        // Wait for HIGH
}

// Skipping parity and stop bits down here.
while (digitalRead(clockPin));           // Wait for LOW.
while (!digitalRead(clockPin));          // Wait for HIGH.
while (digitalRead(clockPin));           // Wait for LOW.
while (!digitalRead(clockPin));          // Wait for HIGH.

return val;
}