Use SPI to send commands to the WS2801 strip
This commit is contained in:
Thomas Kolb
parent
2437c7b18d
commit
9b9f6ee3d6
2
Makefile
2
Makefile
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@ -7,7 +7,7 @@ LD=gcc
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# default build configuration
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# "make BUILD=release" does a release build
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BUILD:=release
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BUILD:=debug
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# basic build flags configuration
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CFLAGS+=-std=c99 -Wall -pedantic -Wno-long-long -D_POSIX_C_SOURCE=20120607L -D_FILE_OFFSET_BITS=64
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125
src/ws2801.c
125
src/ws2801.c
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@ -3,76 +3,77 @@
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#include <malloc.h>
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#include <errno.h>
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#include <wiringPi.h>
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#include <unistd.h>
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#include <fcntl.h>
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#include <sys/ioctl.h>
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#include <sys/types.h>
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#include <linux/spi/spidev.h>
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//#include <wiringPi.h>
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#include "../include/logger.h"
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#include "../include/ws2801.h"
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#define WS2801_CLK_GPIO 17
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#define WS2801_DAT_GPIO 18
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static const char *spi_dev = "/dev/spidev0.0";
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static const uint32_t spi_speed = 250000; // clock freq in Hz
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static const uint16_t spi_delay = 0; // us
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static const uint8_t spi_bits = 8; // bits per word
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// the interface rpi->ws2801 is active low
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#define BUS_HIGH LOW
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#define BUS_LOW HIGH
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uint8_t *modRed = NULL;
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uint8_t *modGreen = NULL;
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uint8_t *modBlue = NULL;
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uint8_t numModules;
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uint8_t *message;
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void busy_wait(void)
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int spi_fd = 0;
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void send_message(void)
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{
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static const struct timespec bitsleep = {0, 1000};
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nanosleep(&bitsleep, NULL);
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struct spi_ioc_transfer tr = {
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.tx_buf = (unsigned long)message,
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.rx_buf = (unsigned long)NULL,
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.len = 3 * numModules,
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.delay_usecs = spi_delay,
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.speed_hz = spi_speed,
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.bits_per_word = 8
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};
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if(ioctl(spi_fd, SPI_IOC_MESSAGE(1), &tr) < 0) {
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LOG(LVL_ERR, "ws2801: could not send SPI message: %s", strerror(errno));
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}
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void send_bit(uint8_t value)
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{
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digitalWrite(WS2801_DAT_GPIO, (value ? BUS_HIGH : BUS_LOW));
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digitalWrite(WS2801_CLK_GPIO, BUS_LOW);
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busy_wait();
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// rising edge at clock
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digitalWrite(WS2801_CLK_GPIO, BUS_HIGH);
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busy_wait();
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}
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void send_commit_condition(void)
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{
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digitalWrite(WS2801_DAT_GPIO, BUS_LOW);
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digitalWrite(WS2801_CLK_GPIO, BUS_LOW);
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}
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void send_byte(uint8_t byte)
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{
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for(int i = 0; i <= 7; i++) {
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send_bit(byte & 0x1);
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byte >>= 1;
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}
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}
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void send_colour(uint8_t red, uint8_t green, uint8_t blue)
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{
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send_byte(red);
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send_byte(green);
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send_byte(blue);
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}
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int ws2801_init(uint8_t nMod)
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{
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if(wiringPiSetupGpio() == -1) {
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LOG(LVL_FATAL, "ws2801: wiringPi setup failed: %s", strerror(errno));
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// Initialize SPI
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// We need to have stable data at falling edge of the spi interface (this
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// means rising edge at the led strip, as the signal is inverted.
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uint8_t spi_mode = SPI_NO_CS | SPI_CPOL;
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spi_fd = open(spi_dev, O_RDWR);
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if(spi_fd < 0) {
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LOG(LVL_ERR, "ws2801: cannot open %s: %s", spi_dev, strerror(errno));
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return -1;
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}
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numModules = nMod;
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modRed = malloc(nMod * sizeof(uint8_t));
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modGreen = malloc(nMod * sizeof(uint8_t));
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modBlue = malloc(nMod * sizeof(uint8_t));
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if(ioctl(spi_fd, SPI_IOC_WR_MODE, &spi_mode) == -1) {
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LOG(LVL_ERR, "ws2801: cannot change SPI mode: %s", strerror(errno));
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return -1;
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}
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if(!modRed || !modGreen || !modBlue) {
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LOG(LVL_ERR, "ws2801: could not allocate all colour arrays!");
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if(ioctl(spi_fd, SPI_IOC_WR_BITS_PER_WORD, &spi_bits) == -1) {
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LOG(LVL_ERR, "ws2801: cannot change SPI bits per word: %s", strerror(errno));
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return -1;
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}
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if(ioctl(spi_fd, SPI_IOC_WR_MAX_SPEED_HZ, &spi_speed) == -1) {
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LOG(LVL_ERR, "ws2801: cannot change SPI speed: %s", strerror(errno));
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return -1;
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}
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// create the message array
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numModules = nMod;
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message = malloc(3 * nMod * sizeof(uint8_t));
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if(!message) {
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LOG(LVL_ERR, "ws2801: could not allocate the message array!");
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return -1;
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}
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@ -81,25 +82,21 @@ int ws2801_init(uint8_t nMod)
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void ws2801_shutdown(void)
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{
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if(modRed != NULL) { free(modRed); modRed = NULL; }
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if(modGreen != NULL) { free(modGreen); modGreen = NULL; }
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if(modBlue != NULL) { free(modBlue); modBlue = NULL; }
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close(spi_fd);
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if(message != NULL) { free(message); message = NULL; }
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}
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void ws2801_set_colour(uint8_t module, uint8_t red, uint8_t green, uint8_t blue)
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{
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modRed[module] = red;
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modGreen[module] = green;
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modBlue[module] = blue;
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message[3*module + 0] = ~red;
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message[3*module + 1] = ~green;
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message[3*module + 2] = ~blue;
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}
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void ws2801_send_update(void)
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{
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for(uint8_t i = 0; i < numModules; i++) {
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send_colour(modRed[i], modGreen[i], modBlue[i]);
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}
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send_commit_condition();
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send_message();
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static const struct timespec sleepval = {0, 550000};
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nanosleep(&sleepval, NULL);
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