RGB Light Show

1#include <stdint.h>
2#include "inc/hw_memmap.h"
3#include "driverlib/sysctl.h"
4#include "driverlib/gpio.h"
5 
6#define LED_ALL (GPIO_PIN_1 | GPIO_PIN_2 | GPIO_PIN_3)
7#define PWM_STEPS 256
8 
9static void showColor(uint8_t r, uint8_t g, uint8_t b, uint32_t periods) {
10    volatile uint32_t p, i;
11    for (p = 0; p < periods; p++)
12        for (i = 0; i < PWM_STEPS; i++) {
13            uint8_t out = 0;
14            if (i < r) out |= GPIO_PIN_1;
15            if (i < g) out |= GPIO_PIN_3;
16            if (i < b) out |= GPIO_PIN_2;
17            GPIOPinWrite(GPIO_PORTF_BASE, LED_ALL, out);
18            SysCtlDelay(2);
19        }
20}
21 
22// Color wheel: 0..255 -> a rainbow color
23static void wheel(uint8_t pos, uint8_t *r, uint8_t *g, uint8_t *b) {
24    if (pos < 85)       { *r = 255 - pos * 3; *g = pos * 3;       *b = 0; }
25    else if (pos < 170) { pos -= 85;  *r = 0; *g = 255 - pos * 3; *b = pos * 3; }
26    else                { pos -= 170; *r = pos * 3; *g = 0;       *b = 255 - pos * 3; }
27}
28 
29int main(void) {
30    SysCtlClockSet(SYSCTL_SYSDIV_4 | SYSCTL_USE_PLL |
31                   SYSCTL_OSC_MAIN | SYSCTL_XTAL_16MHZ);
32    SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOF);
33    while (!SysCtlPeripheralReady(SYSCTL_PERIPH_GPIOF)) {}
34    GPIOPinTypeGPIOOutput(GPIO_PORTF_BASE, LED_ALL);
35 
36    uint8_t r, g, b; uint16_t pos;
37    while (1)
38        for (pos = 0; pos < 256; pos++) {
39            wheel((uint8_t)pos, &r, &g, &b);
40            showColor(r, g, b, 3);                       // smooth transition
41        }
42}