8x8 LED Matrix

1#include <stdint.h>
2#include <stdbool.h>
3#include "inc/hw_memmap.h"
4#include "driverlib/sysctl.h"
5#include "driverlib/gpio.h"
6#include "driverlib/pin_map.h"
7#include "driverlib/ssi.h"
8 
9// MAX7219 register addresses
10#define REG_DECODE    0x09
11#define REG_INTENSITY 0x0A
12#define REG_SCANLIMIT 0x0B
13#define REG_SHUTDOWN  0x0C
14#define REG_DISPTEST  0x0F
15 
16static void delayMs(uint32_t ms) { SysCtlDelay((SysCtlClockGet() / 3000) * ms); }
17 
18// Send one 16-bit word (address<<8 | data) to the MAX7219
19static void maxWrite(uint8_t addr, uint8_t data) {
20    SSIDataPut(SSI2_BASE, ((uint16_t)addr << 8) | data);
21    while (SSIBusy(SSI2_BASE)) {}
22}
23 
24// Push an 8-row frame (rows[0] = top row)
25static void showFrame(const uint8_t rows[8]) {
26    uint8_t i;
27    for (i = 0; i < 8; i++) maxWrite(i + 1, rows[i]);    // digit regs 1..8
28}
29 
30static const uint8_t HEART[8] = { 0x00, 0x66, 0xFF, 0xFF, 0xFF, 0x7E, 0x3C, 0x18 };
31static const uint8_t SMILE[8] = { 0x3C, 0x42, 0xA5, 0x81, 0xA5, 0x99, 0x42, 0x3C };
32static const uint8_t ARROW[8] = { 0x18, 0x3C, 0x7E, 0xFF, 0x18, 0x18, 0x18, 0x18 };
33static const uint8_t CHECK[8] = { 0x00, 0x01, 0x02, 0x04, 0x88, 0x50, 0x20, 0x00 };
34 
35int main(void) {
36    SysCtlClockSet(SYSCTL_SYSDIV_4 | SYSCTL_USE_PLL |
37                   SYSCTL_OSC_MAIN | SYSCTL_XTAL_16MHZ);
38 
39    SysCtlPeripheralEnable(SYSCTL_PERIPH_SSI2);
40    SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOB);
41    while (!SysCtlPeripheralReady(SYSCTL_PERIPH_SSI2)) {}
42    while (!SysCtlPeripheralReady(SYSCTL_PERIPH_GPIOB)) {}
43 
44    GPIOPinConfigure(GPIO_PB4_SSI2CLK);                   // PB4=CLK, PB5=CS, PB6=DIN
45    GPIOPinConfigure(GPIO_PB5_SSI2FSS);
46    GPIOPinConfigure(GPIO_PB6_SSI2TX);
47    GPIOPinTypeSSI(GPIO_PORTB_BASE, GPIO_PIN_4 | GPIO_PIN_5 | GPIO_PIN_6);
48 
49    SSIConfigSetExpClk(SSI2_BASE, SysCtlClockGet(), SSI_FRF_MOTO_MODE_0,
50                       SSI_MODE_MASTER, 1000000, 16);     // mode 0, master, 1 MHz, 16-bit
51    SSIEnable(SSI2_BASE);
52 
53    maxWrite(REG_DISPTEST,  0x00);                        // display test off
54    maxWrite(REG_DECODE,    0x00);                        // no BCD decode -> raw pixels
55    maxWrite(REG_SCANLIMIT, 0x07);                        // all 8 rows
56    maxWrite(REG_INTENSITY, 0x06);                        // brightness 0..15
57    maxWrite(REG_SHUTDOWN,  0x01);                        // wake up
58 
59    while (1) {
60        showFrame(HEART); delayMs(900);
61        showFrame(SMILE); delayMs(900);
62        showFrame(ARROW); delayMs(900);
63        showFrame(CHECK); delayMs(900);
64    }
65}