LED Matrix for Raspberry Pi - Max7219

// blink.c
//
// Example program for bcm2835 library
// Blinks a pin on an off every 0.5 secs
//
// After installing bcm2835, you can build this
// with something like:
// make or gcc -o led led.c -lbcm2835
// sudo ./led
/*
             define from bcm2835.h                       define from Board DVK511
                 3.3V | | 5V               ->                 3.3V | | 5V
    RPI_V2_GPIO_P1_03 | | 5V               ->                  SDA | | 5V
    RPI_V2_GPIO_P1_05 | | GND              ->                  SCL | | GND
       RPI_GPIO_P1_07 | | RPI_GPIO_P1_08   ->                  IO7 | | TX
                  GND | | RPI_GPIO_P1_10   ->                  GND | | RX
       RPI_GPIO_P1_11 | | RPI_GPIO_P1_12   ->                  IO0 | | IO1
    RPI_V2_GPIO_P1_13 | | GND              ->                  IO2 | | GND
       RPI_GPIO_P1_15 | | RPI_GPIO_P1_16   ->                  IO3 | | IO4
                  VCC | | RPI_GPIO_P1_18   ->                  VCC | | IO5
       RPI_GPIO_P1_19 | | GND              ->                 MOSI | | GND
       RPI_GPIO_P1_21 | | RPI_GPIO_P1_22   ->                 MISO | | IO6
       RPI_GPIO_P1_23 | | RPI_GPIO_P1_24   ->                  SCK | | CE0
                  GND | | RPI_GPIO_P1_26   ->                  GND | | CE1

::if your raspberry Pi is version 1 or rev 1 or rev A
RPI_V2_GPIO_P1_03->RPI_GPIO_P1_03
RPI_V2_GPIO_P1_05->RPI_GPIO_P1_05
RPI_V2_GPIO_P1_13->RPI_GPIO_P1_13:
*/

#include <bcm2835.h>
#include <stdio.h>

typedef unsigned char uchar;
typedef unsigned int uint;

#define Max7219_pinCS  RPI_GPIO_P1_24

uchar disp1[38][8] = {
    // 0 to 9, A to Z, and special characters
};

void Delay_xms(uint x) {
    bcm2835_delay(x);
}

void Write_Max7219_byte(uchar DATA) {
    uchar i;
    bcm2835_gpio_write(Max7219_pinCS, LOW);
    bcm2835_spi_transfer(DATA);
}

void Write_Max7219(uchar address1, uchar dat1, uchar address2, uchar dat2) {
    bcm2835_gpio_write(Max7219_pinCS, LOW);

    Write_Max7219_byte(address1);
    Write_Max7219_byte(dat1);
    Write_Max7219_byte(address2);
    Write_Max7219_byte(dat2);

    bcm2835_gpio_write(Max7219_pinCS, HIGH);
}

void Init_MAX7219(void) {
    Write_Max7219(0x09, 0x00, 0x09, 0x00);
    Write_Max7219(0x0a, 0x03, 0x0a, 0x03);
    Write_Max7219(0x0b, 0x07, 0x0b, 0x07);
    Write_Max7219(0x0c, 0x01, 0x0c, 0x01);
    Write_Max7219(0x0f, 0x00, 0x0f, 0x00);
}

int main(void) {
    uchar i, j;
    if (!bcm2835_init()) return 1;

    bcm2835_spi_begin();
    bcm2835_spi_setBitOrder(BCM2835_SPI_BIT_ORDER_MSBFIRST);
    bcm2835_spi_setDataMode(BCM2835_SPI_MODE0);
    bcm2835_spi_setClockDivider(BCM2835_SPI_CLOCK_DIVIDER_256);

    bcm2835_gpio_fsel(Max7219_pinCS, BCM2835_GPIO_FSEL_OUTP);

    Delay_xms(50);
    Init_MAX7219();

    while(1) {
        for(j = 0; j < 37; j++) {
            for(i = 1; i < 9; i++) {
                Write_Max7219(i, disp1[j+1][i-1], i, disp1[j][i-1]);
            }
            Delay_xms(1000);
        }
    }

    bcm2835_spi_end();
    bcm2835_close();

    return 0;
}