LED Matrix - letters with Arduino and Python :)

binascii.py

# Generate C header from CGA font data

import struct

with open("rawcga.bin", "r") as fi:
    data = fi.read()
with open("rawcga.h", "w") as fo:
    fo.write("char RAW_CGA[2048] = { ")
    bytevalues = []
    for byte in data:
        byte = struct.unpack("B", byte)[0]
        # unmangle bit order (12345670 > 01234567)
        byte = ((byte & 1) << 7) + byte >> 1
        bytevalues.append("{:#x}".format(byte))
    fo.write(", ".join(bytevalues))
    fo.write(" };")

clock.py

# Continuously output time (24H) to serial to display on matrix

import time

import serial

ser = serial.Serial(port='COM10')

print "Connected to COM port, waiting 5 seconds for arduino to reset"

time.sleep(5)

print "Starting:"

while 1:
    data = b"\x7f"+time.strftime("%H:%M:%S ").encode("ascii")
    ser.write(data)
    print(repr(data))
    time.sleep(1)

MatrixScan.ino

// from http://overcode.yak.net/12 converted using pngascii.py
char FONT_DATA[1024] = { 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xf7, 0xf7, 0xf7, 0xf7, 0xf7, 0xff, 0xf7, 0xff, 0xeb, 0xeb, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xeb, 0xeb, 0x80, 0xeb, 0x80, 0xeb, 0xeb, 0xff, 0xf7, 0xe1, 0xd7, 0xe3, 0xf5, 0xc3, 0xf7, 0xff, 0xff, 0xcd, 0xcb, 0xf7, 0xe9, 0xd9, 0xff, 0xff, 0xe7, 0xd7, 0xef, 0xd7, 0xb9, 0xbb, 0xc5, 0xff, 0xf7, 0xf7, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfb, 0xf7, 0xef, 0xef, 0xef, 0xf7, 0xfb, 0xff, 0xef, 0xf7, 0xfb, 0xfb, 0xfb, 0xf7, 0xef, 0xff, 0xf7, 0xb6, 0xd5, 0xe3, 0xd5, 0xb6, 0xf7, 0xff, 0xf7, 0xf7, 0xf7, 0x80, 0xf7, 0xf7, 0xf7, 0xff, 0xff, 0xff, 0xff, 0xff, 0xf3, 0xf3, 0xfb, 0xf7, 0xff, 0xff, 0xff, 0x80, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xf3, 0xf3, 0xff, 0xfe, 0xfd, 0xfb, 0xf7, 0xef, 0xdf, 0xbf, 0xff, 0xe3, 0xdd, 0xdd, 0xd5, 0xdd, 0xdd, 0xe3, 0xff, 0xf7, 0xe7, 0xf7, 0xf7, 0xf7, 0xf7, 0xe3, 0xff, 0xe3, 0xdd, 0xfd, 0xfb, 0xf7, 0xef, 0xc1, 0xff, 0xe3, 0xdd, 0xfd, 0xf3, 0xfd, 0xdd, 0xe3, 0xff, 0xf3, 0xeb, 0xdb, 0xc1, 0xfb, 0xfb, 0xf1, 0xff, 0xc1, 0xdf, 0xdf, 0xc3, 0xfd, 0xdd, 0xe3, 0xff, 0xe3, 0xdd, 0xdf, 0xc3, 0xdd, 0xdd, 0xe3, 0xff, 0xc1, 0xfd, 0xfb, 0xf7, 0xef, 0xef, 0xef, 0xff, 0xe3, 0xdd, 0xdd, 0xe3, 0xdd, 0xdd, 0xe3, 0xff, 0xe3, 0xdd, 0xdd, 0xe1, 0xfd, 0xdd, 0xe3, 0xff, 0xff, 0xf3, 0xf3, 0xff, 0xf3, 0xf3, 0xff, 0xff, 0xff, 0xf3, 0xf3, 0xff, 0xf3, 0xf3, 0xfb, 0xf7, 0xfb, 0xf7, 0xef, 0xdf, 0xef, 0xf7, 0xfb, 0xff, 0xff, 0xff, 0x80, 0xff, 0x80, 0xff, 0xff, 0xff, 0xdf, 0xef, 0xf7, 0xfb, 0xf7, 0xef, 0xdf, 0xff, 0xe3, 0xdd, 0xfd, 0xfb, 0xf7, 0xff, 0xf7, 0xff, 0xe3, 0xdd, 0xd1, 0xd5, 0xd1, 0xdf, 0xe3, 0xff, 0xe3, 0xdd, 0xdd, 0xc1, 0xdd, 0xdd, 0xdd, 0xff, 0xc3, 0xdd, 0xdd, 0xc3, 0xdd, 0xdd, 0xc3, 0xff, 0xe3, 0xdd, 0xdf, 0xdf, 0xdf, 0xdd, 0xe3, 0xff, 0xc3, 0xdd, 0xdd, 0xdd, 0xdd, 0xdd, 0xc3, 0xff, 0xc1, 0xdf, 0xdf, 0xc3, 0xdf, 0xdf, 0xc1, 0xff, 0xc1, 0xdf, 0xdf, 0xc1, 0xdf, 0xdf, 0xdf, 0xff, 0xe3, 0xdd, 0xdf, 0xd1, 0xdd, 0xdd, 0xe3, 0xff, 0xdd, 0xdd, 0xdd, 0xc1, 0xdd, 0xdd, 0xdd, 0xff, 0xe3, 0xf7, 0xf7, 0xf7, 0xf7, 0xf7, 0xe3, 0xff, 0xf1, 0xfb, 0xfb, 0xfb, 0xdb, 0xdb, 0xe7, 0xff, 0xdd, 0xdd, 0xdb, 0xc7, 0xdb, 0xdd, 0xdd, 0xff, 0xef, 0xef, 0xef, 0xef, 0xef, 0xef, 0xe1, 0xff, 0xbe, 0x9c, 0xaa, 0xb6, 0xbe, 0xbe, 0xbe, 0xff, 0xdd, 0xcd, 0xd5, 0xd5, 0xd9, 0xdd, 0xdd, 0xff, 0xe3, 0xdd, 0xdd, 0xdd, 0xdd, 0xdd, 0xe3, 0xff, 0xe3, 0xed, 0xed, 0xe3, 0xef, 0xef, 0xef, 0xff, 0xe3, 0xdd, 0xdd, 0xdd, 0xdd, 0xdd, 0xe3, 0xf9, 0xc3, 0xdd, 0xdd, 0xc3, 0xd7, 0xdb, 0xdd, 0xff, 0xe3, 0xdd, 0xdf, 0xe3, 0xfd, 0xdd, 0xe3, 0xff, 0xc1, 0xf7, 0xf7, 0xf7, 0xf7, 0xf7, 0xf7, 0xff, 0xdd, 0xdd, 0xdd, 0xdd, 0xdd, 0xdd, 0xe3, 0xff, 0xdd, 0xdd, 0xdd, 0xeb, 0xeb, 0xf7, 0xf7, 0xff, 0xbe, 0xbe, 0xbe, 0xd5, 0xd5, 0xeb, 0xeb, 0xff, 0xdd, 0xdd, 0xeb, 0xf7, 0xeb, 0xdd, 0xdd, 0xff, 0xdd, 0xdd, 0xeb, 0xf7, 0xf7, 0xf7, 0xf7, 0xff, 0xc1, 0xfd, 0xfb, 0xf7, 0xef, 0xdf, 0xc1, 0xff, 0xe3, 0xef, 0xef, 0xef, 0xef, 0xef, 0xe3, 0xff, 0xbf, 0xdf, 0xef, 0xf7, 0xfb, 0xfd, 0xfe, 0xff, 0xe3, 0xfb, 0xfb, 0xfb, 0xfb, 0xfb, 0xe3, 0xff, 0xf7, 0xeb, 0xdd, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x80, 0xef, 0xf7, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xe3, 0xfd, 0xe1, 0xdd, 0xdd, 0xe2, 0xff, 0xef, 0xef, 0xe3, 0xed, 0xed, 0xed, 0xd3, 0xff, 0xff, 0xff, 0xe3, 0xdf, 0xdf, 0xdf, 0xe3, 0xff, 0xfd, 0xfd, 0xf1, 0xed, 0xed, 0xed, 0xf2, 0xff, 0xff, 0xff, 0xe3, 0xdd, 0xc1, 0xdf, 0xe3, 0xff, 0xf3, 0xed, 0xef, 0xc7, 0xef, 0xef, 0xef, 0xff, 0xff, 0xff, 0xe2, 0xdd, 0xdd, 0xe1, 0xfd, 0xe3, 0xdf, 0xdf, 0xd3, 0xcd, 0xdd, 0xdd, 0xdd, 0xff, 0xff, 0xf7, 0xff, 0xf7, 0xf7, 0xf7, 0xf7, 0xff, 0xff, 0xf7, 0xff, 0xf7, 0xf7, 0xf7, 0xf7, 0xcf, 0xdf, 0xdf, 0xdb, 0xd7, 0xcf, 0xd7, 0xdb, 0xff, 0xe7, 0xf7, 0xf7, 0xf7, 0xf7, 0xf7, 0xf7, 0xff, 0xff, 0xff, 0x49, 0xb6, 0xb6, 0xbe, 0xbe, 0xff, 0xff, 0xff, 0xd3, 0xed, 0xed, 0xed, 0xed, 0xff, 0xff, 0xff, 0xe3, 0xdd, 0xdd, 0xdd, 0xe3, 0xff, 0xff, 0xff, 0xd3, 0xed, 0xed, 0xe3, 0xef, 0xef, 0xff, 0xff, 0xe5, 0xdb, 0xdb, 0xe3, 0xfb, 0xfb, 0xff, 0xff, 0xd3, 0xcf, 0xdf, 0xdf, 0xdf, 0xff, 0xff, 0xff, 0xe3, 0xdf, 0xe7, 0xfb, 0xc7, 0xff, 0xff, 0xf7, 0xe3, 0xf7, 0xf7, 0xf7, 0xf7, 0xff, 0xff, 0xff, 0xdb, 0xdb, 0xdb, 0xdb, 0xe5, 0xff, 0xff, 0xff, 0xdd, 0xdd, 0xdd, 0xeb, 0xf7, 0xff, 0xff, 0xff, 0xbe, 0xbe, 0xb6, 0xaa, 0xdd, 0xff, 0xff, 0xff, 0xdd, 0xeb, 0xf7, 0xeb, 0xdd, 0xff, 0xff, 0xff, 0xed, 0xed, 0xed, 0xf1, 0xfd, 0xe3, 0xff, 0xff, 0xc3, 0xfb, 0xf7, 0xef, 0xc3, 0xff, 0xf3, 0xef, 0xef, 0xdf, 0xef, 0xef, 0xf3, 0xff, 0xf7, 0xf7, 0xf7, 0xf7, 0xf7, 0xf7, 0xf7, 0xff, 0xcf, 0xf7, 0xf7, 0xfb, 0xf7, 0xf7, 0xcf, 0xff, 0xff, 0xff, 0xcf, 0xb6, 0xf9, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff };

// Font line macro
#define FONT_ROW(c, r) (~FONT_DATA[c*8+r])

// Message buffer
char message[200];
// Message length
int message_len = 0;


//Pin connected to ST_CP of 74HC595
int latchPin = 8;
//Pin connected to SH_CP of 74HC595
int clockPin = 12;
////Pin connected to DS of 74HC595
int dataPin = 11;

// Power pins for each row
int ROWPIN[] = {
  2,
  3,
  4,
  5,
  6,
  7,
  9,
  10
};

// Outputted row values
int ROW[8];

void setup() {
  //set pins to output so you can control the shift register
  pinMode(latchPin, OUTPUT);
  pinMode(clockPin, OUTPUT);
  pinMode(dataPin, OUTPUT);
  
  for (int r = 0; r < 8; r++) {
    pinMode(ROWPIN[r], OUTPUT); 
  }
  
  Serial.begin(9600);
}

void lightMatrix() {
  for (int r = 0; r < 8; r++) {
    // take the latchPin low so 
    // the LEDs don't change while you're sending in bits:
    digitalWrite(latchPin, LOW);
       
    // shift out the bits: (inverted since sinking current)
    shiftOut(dataPin, clockPin, LSBFIRST, ~ROW[r]);  

    //take the latch pin high so the columns will be sunk:
    digitalWrite(latchPin, HIGH);
    
    //take the row pin high so the rows will be powered:
    digitalWrite(ROWPIN[r], HIGH);
    
    delay(1);
    
    // take the row pin low so the row will be unpowered:
    digitalWrite(ROWPIN[r], LOW);
  }
}

// PC sends rows to display (each row is byte)
void getSerialRows() {
  static int curSerialRow = 0;
  while (Serial.available() > 0) {
    if (curSerialRow > 7)
      curSerialRow = 0;
    ROW[curSerialRow] = Serial.read();
    curSerialRow++;
  } 
}

// PC sends ASCII text to display
void getSerialMessage() {
  while (Serial.available() > 0) {
    char c;
    
    c = Serial.read();
    
    if (c == 0x7f) { // 0x7f resets message buffer
      message_len = 0;
    }else{
      if (message_len >= 100)
        message_len = 0;
      message[message_len] = c;
      message_len++;
    }
  } 
}

#define tickinc 8
#define tickmax 8
// Scrolling text
void scrollMessage() {
  static char c1 = 0x7f;
  static char c2 = 0x7f;
  static int tick = tickmax*tickinc;
  static int stringpos = -1;
  
  if (tick >= tickinc*tickmax) {   
    tick = 0;
    
    stringpos++;
    if (stringpos >= message_len)
      stringpos = 0;
    c1 = c2;
    c2 = message[stringpos];
  }
 
  for (int r = 0; r < 8; r++) {
     if (r-tick/tickinc >= 0 and r-tick/tickinc < 8)
       ROW[r-tick/tickinc] = FONT_ROW(c1, r);
  
     if (r-tick/tickinc+8 >= 0 and r-tick/tickinc+8 < 8)
       ROW[r-tick/tickinc+8] = FONT_ROW(c2, r);     
  }
  
  tick++; 
}

void loop() { 
  // Display rows
  lightMatrix();
  // Check for serial input
  getSerialMessage();
  // Change rows
  scrollMessage();
}

pngascii.py

# Generate C header from PNG font

import struct

import Image
fn = Image.open("8x8font.png")

def getCharFromImage(char, img):
    code = ord(char)
    lines = []
    for y in range(8):
        line = ""
        for x in range(8):
            px = img.getpixel( (code*8 + x, y) )
            line += "1" if px else "0"
        lines.append(line)
    return lines

def binaryChar(char):
    chardata = getCharFromImage(char, fn)
    binarydata = b""
    for row in chardata:
        num = int(row, 2)
        binarydata += struct.pack("B", num)
    return binarydata
     
with open("font.h", "w") as f:
    data = []
    for char in range(128):
        for byte in binaryChar(chr(char)):
            data.append(byte)
    f.write("char FONT_DATA[1024] = { ")
    f.write(", ".join(["{:#x}".format(struct.unpack("B", byte)[0]) for byte in data]))
    f.write(" };")