Makefile

@@ -1,5 +1,5 @@
 CC=gcc
-CFLAGS=-O2 -std=c89 -W -Werror -Wall -Wextra -pedantic -I. 
+CFLAGS=-O2 -std=c99 -W -Werror -Wall -Wextra -pedantic -I. 
 LFLAGS=-lm
 all:
 	$(CC) $(CFLAGS) main.c i2c.c lis3dh.c -o lis3dh $(LFLAGS)

i2c.c

@@ -38,11 +38,7 @@ int i2c_init(void) {
 
 
 int i2c_read(uint8_t reg, uint8_t *dst, uint32_t size) {
-	uint8_t cmd[2];
+	uint8_t cmd[2] = {reg, 0x00};
-
-	cmd[0] = reg;
-	cmd[1] = 0x00;
-
 	write(fd, cmd, 2);
 	
 	if (read(fd, dst, size) != (ssize_t)size) {
@@ -56,10 +52,7 @@ int i2c_read(uint8_t reg, uint8_t *dst, uint32_t size) {
 
 
 int i2c_write(uint8_t reg, uint8_t value) {
-	uint8_t cmd[2];
+	uint8_t cmd[2] = {reg, value};
-
-	cmd[0] = reg;
-	cmd[1] = value;
 	
 	if (write(fd, cmd, 2) != 2) {
 		fprintf(stderr, "error write()\n");

lis3dh.c

@@ -59,7 +59,7 @@ int lis3dh_init(lis3dh_t *lis3dh) {
     lis3dh->cfg.fifo.fth = 32; /* default watermark level. */
     lis3dh->cfg.filter.mode = 0xFF; /* in use if neq 0xFF */
     lis3dh->cfg.filter.cutoff = 0;
-    lis3dh->cfg.filter.fds = 1; /* bypass OFF by default */
+    lis3dh->cfg.filter.fds = 0;
     lis3dh->cfg.filter.hpclick = 0;
     lis3dh->cfg.filter.ia1 = 0;
     lis3dh->cfg.filter.ia2 = 0;
@@ -221,8 +221,9 @@ static uint8_t acc_sensitivity(lis3dh_t *lis3dh) {
 }
 
 int lis3dh_read(lis3dh_t *lis3dh) {
+
     uint8_t data[6];
-    int32_t x, y, z;
+    int16_t x, y, z;
     uint8_t scale, sens;
     int err = 0;
 
@@ -246,7 +247,8 @@ int lis3dh_read(lis3dh_t *lis3dh) {
 }
 
 int lis3dh_read_fifo(lis3dh_t *lis3dh, struct lis3dh_fifo_data *fifo) {
-    int32_t x, y, z;
+
+    int16_t x, y, z;
     uint8_t scale, sens;
     uint8_t data[192]; /* max size */
     int err = 0;
@@ -255,15 +257,14 @@ int lis3dh_read_fifo(lis3dh_t *lis3dh, struct lis3dh_fifo_data *fifo) {
     scale = acc_shift(lis3dh);
     sens = acc_sensitivity(lis3dh);
 
-    /* fifo buffer is max 32 */
+    fifo->size = lis3dh->cfg.fifo.fth;
-    fifo->size = lis3dh->cfg.fifo.fth > 32 ? 32 : lis3dh->cfg.fifo.fth;
 
     /* must set MSbit of the address to multi-read and 
        have the device auto-increment the address.
        see 5.1.5 in datasheet. */
     err |= lis3dh->dev.read(REG_OUT_X_L | 0x80, data, 192);
 
-    for (i=0, idx=0; i<fifo->size * 6; i+=6, idx++) {
+    for(i=0, idx=0; i<lis3dh->cfg.fifo.fth * 6; i+=6, idx++) {
         x = (((int16_t)((data[i + 0] << 8) | data[i + 1])) >> scale) * sens;
         y = (((int16_t)((data[i + 2] << 8) | data[i + 3])) >> scale) * sens;
         z = (((int16_t)((data[i + 4] << 8) | data[i + 5])) >> scale) * sens;

main.c

@@ -22,7 +22,6 @@ int main() {
 
     lis3dh_t lis;
     struct lis3dh_fifo_data fifo;
-    int i, k;
 
     /* set fn ptrs to rw on bus (i2c or SPI) */
     lis.dev.init = i2c_init;
@@ -48,7 +47,7 @@ int main() {
         quit("configure()", &lis);
     }
 
-    for (i=0; i<50; i++) {
+    for (int i=0; i<50; i++) {
     
         /* poll fifo reg */
         if (lis3dh_poll_fifo(&lis)) {
@@ -60,7 +59,7 @@ int main() {
             quit("read_fifo()", &lis);
         }
 
-        for(k=0; k<fifo.size; k++) {
+        for(int k=0; k<fifo.size; k++) {
             printf("x: %04.04f, y: %04.04f, z: %04.04f mag: %04.04f\n",
                 fifo.x[k], fifo.y[k], fifo.z[k],
                 mag(fifo.x[k], fifo.y[k], fifo.z[k]));