i2c

Makefile

@@ -1,4 +1,7 @@
 CC=gcc
 CFLAGS=-O2 -std=gnu99 -W -Werror -Wall -Wextra -I.
 all:
-	$(CC) $(CFLAGS) main.c lis3dh.c -o main
+	$(CC) $(CFLAGS) main.c i2c.c lis3dh.c -o main
+
+clean:
+	rm -rf main

i2c.c

@@ -0,0 +1,71 @@
+/* 
+
+Example I2C use on linux/raspberry pi
+
+*/
+
+#include <stdio.h>
+#include <fcntl.h>
+#include <linux/i2c.h>
+#include <linux/i2c-dev.h>
+#include <stdint.h>
+#include <sys/ioctl.h>
+#include <unistd.h>
+#include <stdlib.h>
+
+#include "i2c.h"
+
+#define I2C_DEVICE "/dev/i2c-1"
+#define I2C_LIS3DH_ADDRESS 0x18
+
+static int fd;
+
+int i2c_init(void) {
+	fd = open(I2C_DEVICE, O_RDWR);
+	if (fd < 0) {
+		fprintf(stderr, "could not open device: %s\n", I2C_DEVICE);
+		return I2C_ERR;
+	}
+
+	if (ioctl(fd, I2C_SLAVE, I2C_LIS3DH_ADDRESS) < 0) {
+		fprintf(stderr, "failed to acquire bus/talk to slave\n");
+		close(fd);
+		return I2C_ERR;
+	}
+
+	return I2C_OK;
+}
+
+
+int i2c_read(uint8_t reg, uint8_t *dst, uint32_t size) {
+	uint8_t cmd[2] = {reg, 0x00};
+	write(fd, cmd, 2);
+	
+	if (read(fd, dst, size) != (ssize_t)size) {
+		fprintf(stderr, "error read()\n");
+		return I2C_ERR;
+	
+	}
+
+	return I2C_OK;
+}
+
+
+int i2c_write(uint8_t reg, uint8_t value) {
+	uint8_t cmd[2] = {reg, value};
+	
+	if (write(fd, cmd, 2) != 2) {
+		fprintf(stderr, "error write()\n");
+		return I2C_ERR;
+	}
+
+	return I2C_OK;
+}
+
+int i2c_deinit(void) {
+	if (fd) {
+		close(fd);
+	}
+
+	return I2C_OK;
+}

i2c.h

@@ -0,0 +1,14 @@
+#ifndef I2C_H
+#define I2C_H
+
+#include <stdint.h>
+
+#define I2C_OK  0
+#define I2C_ERR 1
+
+int i2c_init   (void);
+int i2c_read   (uint8_t reg, uint8_t *dst, uint32_t size);
+int i2c_write  (uint8_t reg, uint8_t value);
+int i2c_deinit (void);
+
+#endif

lis3dh.c

@@ -1,11 +1,22 @@
+#include <stdio.h>
 #include "lis3dh.h"
+#include "registers.h"
 
 int lis3dh_init(lis3dh_t *lis3dh) {
-    lis3dh->cfg.rate = 0;
-    return 0;
+    uint8_t result;
+    int err = 0;
+
+    lis3dh->dev.init();
+
+    err |= lis3dh->dev.read(REG_WHO_AM_I, &result, 1);
+    if (result != 0x33) {
+        err |= 1;
+    }
+
+    return err;
 }
 
 int lis3dh_deinit(lis3dh_t *lis3dh) {
-    lis3dh->cfg.rate = 0;
+    lis3dh->dev.deinit();
     return 0;
 }

main.c

@@ -1,10 +1,20 @@
+#define _GNU_SOURCE
 #include <stdio.h>
+#include <unistd.h>
 #include "lis3dh.h"
+#include "i2c.h"
 
 int main() {
 
     lis3dh_t lis;
 
+    lis.dev.init = i2c_init;
+    lis.dev.read = i2c_read;
+    lis.dev.write = i2c_write;
+    lis.dev.sleep = usleep;
+    lis.dev.deinit = i2c_deinit;
+
+
     if (!lis3dh_init(&lis)) {
         puts("OK");
     }