temperature

lis3dh.c

@@ -1,5 +1,6 @@
 #include <stddef.h>
 #include <string.h>
+#include <stdio.h>
 #include "lis3dh.h"
 #include "registers.h"
 
@@ -412,3 +413,18 @@ int lis3dh_read_adc(lis3dh_t *lis3dh) {
 
     return err;
 }
+
+/* the temperature sensor only reports the difference between its current temp,
+   and the factory calibrated temperature, 25 celsius.
+   in increments of plus or negative 1 unit celsius.
+   the reported temperature is stored inplace of adc3 
+   temp sensing is always in 8-bit mode 
+   operating range: -40 to 85 celsius */
+int lis3dh_read_temp(lis3dh_t *lis3dh) {
+    uint8_t data[2];
+    int err = 0;
+
+    err |= lis3dh->dev.read(REG_OUT_ADC3_L | 0x80, data, 2);
+    lis3dh->adc.adc3 = (float)((int16_t)(data[1] | (data[0] << 8)) >> 8) + 25.0;
+    return err;
+}

lis3dh.h

@@ -225,5 +225,6 @@ int lis3dh_clear_int2(lis3dh_t *lis3dh);
 int lis3dh_reference(lis3dh_t *lis3dh);
 int lis3dh_reset(lis3dh_t *lis3dh);
 int lis3dh_read_adc(lis3dh_t *lis3dh);
+int lis3dh_read_temp(lis3dh_t *lis3dh);
 
 #endif

main.c

@@ -62,6 +62,7 @@ int main() {
     lis.cfg.filter.cutoff = LIS3DH_FILTER_CUTOFF_8;
 
     lis.cfg.en_adc = 1;
+    lis.cfg.en_temp = 1;
     
     /* write device config */
     if (lis3dh_configure(&lis)) {
@@ -89,6 +90,11 @@ int main() {
             quit("read_adc()", &lis);
         }
 
+        /* read temp from ADC3 and overwrite local ADC reading for ADC3 */
+        if (lis3dh_read_temp(&lis)) {
+            quit("read_temp()", &lis);
+        }
+
         for(k=0; k<fifo.size; k++) {
             printf("x: %04.04f y: %04.04f z: %04.04f mag: %04.04f ADC1:%.1f, ADC2:%.1f, ADC3:%.1f\n",
                 fifo.x[k], fifo.y[k], fifo.z[k],