EDIT: Ooops! Can this be please moved to the Multiplexing and LEDs forum? 
Hello, my first post.
After vicious googling I have decided that it is time I am writing here to ask some things that are bothering me.
I have bought arduino and I love it, tried setting up 8x8 matrix with MAX7219 and it worked somewhat, but I have faced problems.
I have tried using MaxMatrix library for rendering text. Sadly, it won't really always render the text correctly or not render at all.
For example, I feed it 'aaaaa' using serial input, but all I get is a straight line and a part of the last 'a'.
If I try printing many characters, like a sentence, my matrix prints weird gibberish for a moment and then just goes blank off.
Also sometimes when I upload my code, my matrix strobes and scrolls randomly and then just doesn't print anything at all.
What can I be doing wrong?
This is my code, it's straight from the samples of MaxMatrix:
#include <MaxMatrix.h>
#include <avr/pgmspace.h>
PROGMEM prog_uchar CH[] = {
3, 8, B0000000, B0000000, B0000000, B0000000, B0000000, // space
1, 8, B1011111, B0000000, B0000000, B0000000, B0000000, // !
3, 8, B0000011, B0000000, B0000011, B0000000, B0000000, // "
5, 8, B0010100, B0111110, B0010100, B0111110, B0010100, // #
4, 8, B0100100, B1101010, B0101011, B0010010, B0000000, // $
5, 8, B1100011, B0010011, B0001000, B1100100, B1100011, // %
5, 8, B0110110, B1001001, B1010110, B0100000, B1010000, // &
1, 8, B0000011, B0000000, B0000000, B0000000, B0000000, // '
3, 8, B0011100, B0100010, B1000001, B0000000, B0000000, // (
3, 8, B1000001, B0100010, B0011100, B0000000, B0000000, // )
5, 8, B0101000, B0011000, B0001110, B0011000, B0101000, // *
5, 8, B0001000, B0001000, B0111110, B0001000, B0001000, // +
2, 8, B10110000, B1110000, B0000000, B0000000, B0000000, // ,
4, 8, B0001000, B0001000, B0001000, B0001000, B0000000, // -
2, 8, B1100000, B1100000, B0000000, B0000000, B0000000, // .
4, 8, B1100000, B0011000, B0000110, B0000001, B0000000, // /
4, 8, B0111110, B1000001, B1000001, B0111110, B0000000, // 0
3, 8, B1000010, B1111111, B1000000, B0000000, B0000000, // 1
4, 8, B1100010, B1010001, B1001001, B1000110, B0000000, // 2
4, 8, B0100010, B1000001, B1001001, B0110110, B0000000, // 3
4, 8, B0011000, B0010100, B0010010, B1111111, B0000000, // 4
4, 8, B0100111, B1000101, B1000101, B0111001, B0000000, // 5
4, 8, B0111110, B1001001, B1001001, B0110000, B0000000, // 6
4, 8, B1100001, B0010001, B0001001, B0000111, B0000000, // 7
4, 8, B0110110, B1001001, B1001001, B0110110, B0000000, // 8
4, 8, B0000110, B1001001, B1001001, B0111110, B0000000, // 9
2, 8, B01010000, B0000000, B0000000, B0000000, B0000000, // :
2, 8, B10000000, B01010000, B0000000, B0000000, B0000000, // ;
3, 8, B0010000, B0101000, B1000100, B0000000, B0000000, // <
3, 8, B0010100, B0010100, B0010100, B0000000, B0000000, // =
3, 8, B1000100, B0101000, B0010000, B0000000, B0000000, // >
4, 8, B0000010, B1011001, B0001001, B0000110, B0000000, // ?
5, 8, B0111110, B1001001, B1010101, B1011101, B0001110, // @
4, 8, B1111110, B0010001, B0010001, B1111110, B0000000, // A
4, 8, B1111111, B1001001, B1001001, B0110110, B0000000, // B
4, 8, B0111110, B1000001, B1000001, B0100010, B0000000, // C
4, 8, B1111111, B1000001, B1000001, B0111110, B0000000, // D
4, 8, B1111111, B1001001, B1001001, B1000001, B0000000, // E
4, 8, B1111111, B0001001, B0001001, B0000001, B0000000, // F
4, 8, B0111110, B1000001, B1001001, B1111010, B0000000, // G
4, 8, B1111111, B0001000, B0001000, B1111111, B0000000, // H
3, 8, B1000001, B1111111, B1000001, B0000000, B0000000, // I
4, 8, B0110000, B1000000, B1000001, B0111111, B0000000, // J
4, 8, B1111111, B0001000, B0010100, B1100011, B0000000, // K
4, 8, B1111111, B1000000, B1000000, B1000000, B0000000, // L
5, 8, B1111111, B0000010, B0001100, B0000010, B1111111, // M
5, 8, B1111111, B0000100, B0001000, B0010000, B1111111, // N
4, 8, B0111110, B1000001, B1000001, B0111110, B0000000, // O
4, 8, B1111111, B0001001, B0001001, B0000110, B0000000, // P
4, 8, B0111110, B1000001, B1000001, B10111110, B0000000, // Q
4, 8, B1111111, B0001001, B0001001, B1110110, B0000000, // R
4, 8, B1000110, B1001001, B1001001, B0110010, B0000000, // S
5, 8, B0000001, B0000001, B1111111, B0000001, B0000001, // T
4, 8, B0111111, B1000000, B1000000, B0111111, B0000000, // U
5, 8, B0001111, B0110000, B1000000, B0110000, B0001111, // V
5, 8, B0111111, B1000000, B0111000, B1000000, B0111111, // W
5, 8, B1100011, B0010100, B0001000, B0010100, B1100011, // X
5, 8, B0000111, B0001000, B1110000, B0001000, B0000111, // Y
4, 8, B1100001, B1010001, B1001001, B1000111, B0000000, // Z
2, 8, B1111111, B1000001, B0000000, B0000000, B0000000, // [
4, 8, B0000001, B0000110, B0011000, B1100000, B0000000, // backslash
2, 8, B1000001, B1111111, B0000000, B0000000, B0000000, // ]
3, 8, B0000010, B0000001, B0000010, B0000000, B0000000, // hat
4, 8, B1000000, B1000000, B1000000, B1000000, B0000000, // _
2, 8, B0000001, B0000010, B0000000, B0000000, B0000000, // `
4, 8, B0100000, B1010100, B1010100, B1111000, B0000000, // a
4, 8, B1111111, B1000100, B1000100, B0111000, B0000000, // b
4, 8, B0111000, B1000100, B1000100, B0101000, B0000000, // c
4, 8, B0111000, B1000100, B1000100, B1111111, B0000000, // d
4, 8, B0111000, B1010100, B1010100, B0011000, B0000000, // e
3, 8, B0000100, B1111110, B0000101, B0000000, B0000000, // f
4, 8, B10011000, B10100100, B10100100, B01111000, B0000000, // g
4, 8, B1111111, B0000100, B0000100, B1111000, B0000000, // h
3, 8, B1000100, B1111101, B1000000, B0000000, B0000000, // i
4, 8, B1000000, B10000000, B10000100, B1111101, B0000000, // j
4, 8, B1111111, B0010000, B0101000, B1000100, B0000000, // k
3, 8, B1000001, B1111111, B1000000, B0000000, B0000000, // l
5, 8, B1111100, B0000100, B1111100, B0000100, B1111000, // m
4, 8, B1111100, B0000100, B0000100, B1111000, B0000000, // n
4, 8, B0111000, B1000100, B1000100, B0111000, B0000000, // o
4, 8, B11111100, B0100100, B0100100, B0011000, B0000000, // p
4, 8, B0011000, B0100100, B0100100, B11111100, B0000000, // q
4, 8, B1111100, B0001000, B0000100, B0000100, B0000000, // r
4, 8, B1001000, B1010100, B1010100, B0100100, B0000000, // s
3, 8, B0000100, B0111111, B1000100, B0000000, B0000000, // t
4, 8, B0111100, B1000000, B1000000, B1111100, B0000000, // u
5, 8, B0011100, B0100000, B1000000, B0100000, B0011100, // v
5, 8, B0111100, B1000000, B0111100, B1000000, B0111100, // w
5, 8, B1000100, B0101000, B0010000, B0101000, B1000100, // x
4, 8, B10011100, B10100000, B10100000, B1111100, B0000000, // y
3, 8, B1100100, B1010100, B1001100, B0000000, B0000000, // z
3, 8, B0001000, B0110110, B1000001, B0000000, B0000000, // {
1, 8, B1111111, B0000000, B0000000, B0000000, B0000000, // |
3, 8, B1000001, B0110110, B0001000, B0000000, B0000000, // }
4, 8, B0001000, B0000100, B0001000, B0000100, B0000000, // ~
};
int data = 2;
int load = 3;
int clock = 4;
int maxInUse = 1; //change this variable to set how many MAX7219's you'll use
MaxMatrix m(data, load, clock, maxInUse);
byte buffer[10];
void setup()
{
m.init();
m.setIntensity(1);
Serial.begin(9600);
}
void loop()
{
while (Serial.available() > 0)
{
byte c = Serial.read();
Serial.println(c, DEC);
printCharWithShift(c, 100);
}
delay(100);
m.shiftLeft(false, true);
}
void printCharWithShift(char c, int shift_speed)
{
if (c < 32) return;
c -= 32;
memcpy_P(buffer, CH + 7*c, 7);
m.writeSprite(32, 0, buffer);
m.setColumn(32 + buffer[0], 0);
for (int i=0; i<buffer[0]+1; i++)
{
delay(shift_speed);
m.shiftLeft(false, false);
}
}
void printStringWithShift(char* s, int shift_speed)
{
while (*s != 0)
{
printCharWithShift(*s, shift_speed);
s++;
}
}I am also attaching my wiring diagram. The pins used are 2 3 4.
