92 lines
1.6 KiB
C
92 lines
1.6 KiB
C
/*
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Example I2C use on linux/raspberry pi
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*/
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#include <stdio.h>
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#include <fcntl.h>
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#include <linux/i2c.h>
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#include <linux/i2c-dev.h>
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#include <stdint.h>
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#include <sys/ioctl.h>
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#include <unistd.h>
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#include <stdlib.h>
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#include "i2c.h"
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/*
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* Pinout config for this example
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*
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* LIS3DH SDA => Raspberry Pi GPIO 2 (Physical pin 3)
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* LIS3DH SCL => Raspberry Pi GPIO 3 (Physical pin 5)
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*
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*/
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#define I2C_DEVICE "/dev/i2c-1"
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#define I2C_LIS3DH_ADDRESS 0x18 /* Can also be 0x19 */
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static int fd;
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int i2c_init(void) {
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fd = open(I2C_DEVICE, O_RDWR);
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if (fd < 0) {
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fprintf(stderr, "i2c_init(): could not open device: %s\n", I2C_DEVICE);
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return 1;
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}
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if (ioctl(fd, I2C_SLAVE, I2C_LIS3DH_ADDRESS) < 0) {
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fprintf(stderr, "i2c_init(): failed to acquire bus/talk to slave\n");
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close(fd);
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return 1;
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}
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return 0;
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}
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int i2c_read(uint8_t reg, uint8_t *dst, uint32_t size) {
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uint8_t cmd[2];
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if (size > 1) {
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reg |= 0x80; /* AUTO INC */
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}
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cmd[0] = reg;
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cmd[1] = 0x00;
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if (write(fd, cmd, 2) != 2) {
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fprintf(stderr, "i2c_read(): error write()\n");
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return 1;
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}
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if (read(fd, dst, size) != (int)size) {
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fprintf(stderr, "i2c_read(): error read()\n");
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return 1;
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}
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return 0;
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}
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int i2c_write(uint8_t reg, uint8_t value) {
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uint8_t cmd[2];
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cmd[0] = reg;
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cmd[1] = value;
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if (write(fd, cmd, 2) != 2) {
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fprintf(stderr, "i2c_write(): error write()\n");
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return 1;
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}
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return 0;
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}
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int i2c_deinit(void) {
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if (fd) {
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close(fd);
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}
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return 0;
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}
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