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Use SPI to send commands to the WS2801 strip

This commit is contained in:
Thomas Kolb 2013-04-12 19:25:23 +02:00
parent 2437c7b18d
commit 9b9f6ee3d6
2 changed files with 61 additions and 64 deletions
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2
Makefile
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@ -7,7 +7,7 @@ LD=gcc
# default build configuration # default build configuration
# "make BUILD=release" does a release build # "make BUILD=release" does a release build
BUILD:=release BUILD:=debug
# basic build flags configuration # basic build flags configuration
CFLAGS+=-std=c99 -Wall -pedantic -Wno-long-long -D_POSIX_C_SOURCE=20120607L -D_FILE_OFFSET_BITS=64 CFLAGS+=-std=c99 -Wall -pedantic -Wno-long-long -D_POSIX_C_SOURCE=20120607L -D_FILE_OFFSET_BITS=64

123
src/ws2801.c
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@ -3,76 +3,77 @@
#include <malloc.h> #include <malloc.h>
#include <errno.h> #include <errno.h>
#include <wiringPi.h> #include <unistd.h>
#include <fcntl.h>
#include <sys/ioctl.h>
#include <sys/types.h>
#include <linux/spi/spidev.h>
//#include <wiringPi.h>
#include "../include/logger.h" #include "../include/logger.h"
#include "../include/ws2801.h" #include "../include/ws2801.h"
#define WS2801_CLK_GPIO 17 static const char *spi_dev = "/dev/spidev0.0";
#define WS2801_DAT_GPIO 18 static const uint32_t spi_speed = 250000; // clock freq in Hz
static const uint16_t spi_delay = 0; // us
static const uint8_t spi_bits = 8; // bits per word
// the interface rpi->ws2801 is active low
#define BUS_HIGH LOW
#define BUS_LOW HIGH
uint8_t *modRed = NULL;
uint8_t *modGreen = NULL;
uint8_t *modBlue = NULL;
uint8_t numModules; uint8_t numModules;
uint8_t *message;
void busy_wait(void) int spi_fd = 0;
void send_message(void)
{ {
static const struct timespec bitsleep = {0, 1000}; struct spi_ioc_transfer tr = {
nanosleep(&bitsleep, NULL); .tx_buf = (unsigned long)message,
} .rx_buf = (unsigned long)NULL,
.len = 3 * numModules,
.delay_usecs = spi_delay,
.speed_hz = spi_speed,
.bits_per_word = 8
};
void send_bit(uint8_t value) if(ioctl(spi_fd, SPI_IOC_MESSAGE(1), &tr) < 0) {
{ LOG(LVL_ERR, "ws2801: could not send SPI message: %s", strerror(errno));
digitalWrite(WS2801_DAT_GPIO, (value ? BUS_HIGH : BUS_LOW));
digitalWrite(WS2801_CLK_GPIO, BUS_LOW);
busy_wait();
// rising edge at clock
digitalWrite(WS2801_CLK_GPIO, BUS_HIGH);
busy_wait();
}
void send_commit_condition(void)
{
digitalWrite(WS2801_DAT_GPIO, BUS_LOW);
digitalWrite(WS2801_CLK_GPIO, BUS_LOW);
}
void send_byte(uint8_t byte)
{
for(int i = 0; i <= 7; i++) {
send_bit(byte & 0x1);
byte >>= 1;
} }
} }
void send_colour(uint8_t red, uint8_t green, uint8_t blue)
{
send_byte(red);
send_byte(green);
send_byte(blue);
}
int ws2801_init(uint8_t nMod) int ws2801_init(uint8_t nMod)
{ {
if(wiringPiSetupGpio() == -1) { // Initialize SPI
LOG(LVL_FATAL, "ws2801: wiringPi setup failed: %s", strerror(errno)); // We need to have stable data at falling edge of the spi interface (this
// means rising edge at the led strip, as the signal is inverted.
uint8_t spi_mode = SPI_NO_CS | SPI_CPOL;
spi_fd = open(spi_dev, O_RDWR);
if(spi_fd < 0) {
LOG(LVL_ERR, "ws2801: cannot open %s: %s", spi_dev, strerror(errno));
return -1; return -1;
} }
numModules = nMod; if(ioctl(spi_fd, SPI_IOC_WR_MODE, &spi_mode) == -1) {
modRed = malloc(nMod * sizeof(uint8_t)); LOG(LVL_ERR, "ws2801: cannot change SPI mode: %s", strerror(errno));
modGreen = malloc(nMod * sizeof(uint8_t)); return -1;
modBlue = malloc(nMod * sizeof(uint8_t)); }
if(!modRed || !modGreen || !modBlue) { if(ioctl(spi_fd, SPI_IOC_WR_BITS_PER_WORD, &spi_bits) == -1) {
LOG(LVL_ERR, "ws2801: could not allocate all colour arrays!"); LOG(LVL_ERR, "ws2801: cannot change SPI bits per word: %s", strerror(errno));
return -1;
}
if(ioctl(spi_fd, SPI_IOC_WR_MAX_SPEED_HZ, &spi_speed) == -1) {
LOG(LVL_ERR, "ws2801: cannot change SPI speed: %s", strerror(errno));
return -1;
}
// create the message array
numModules = nMod;
message = malloc(3 * nMod * sizeof(uint8_t));
if(!message) {
LOG(LVL_ERR, "ws2801: could not allocate the message array!");
return -1; return -1;
} }
@ -81,25 +82,21 @@ int ws2801_init(uint8_t nMod)
void ws2801_shutdown(void) void ws2801_shutdown(void)
{ {
if(modRed != NULL) { free(modRed); modRed = NULL; } close(spi_fd);
if(modGreen != NULL) { free(modGreen); modGreen = NULL; }
if(modBlue != NULL) { free(modBlue); modBlue = NULL; } if(message != NULL) { free(message); message = NULL; }
} }
void ws2801_set_colour(uint8_t module, uint8_t red, uint8_t green, uint8_t blue) void ws2801_set_colour(uint8_t module, uint8_t red, uint8_t green, uint8_t blue)
{ {
modRed[module] = red; message[3*module + 0] = ~red;
modGreen[module] = green; message[3*module + 1] = ~green;
modBlue[module] = blue; message[3*module + 2] = ~blue;
} }
void ws2801_send_update(void) void ws2801_send_update(void)
{ {
for(uint8_t i = 0; i < numModules; i++) { send_message();
send_colour(modRed[i], modGreen[i], modBlue[i]);
}
send_commit_condition();
static const struct timespec sleepval = {0, 550000}; static const struct timespec sleepval = {0, 550000};
nanosleep(&sleepval, NULL); nanosleep(&sleepval, NULL);