drivers/lsm303dlhc: normalized SAUL readings

drivers/include/lsm303dlhc.h

@@ -101,11 +101,13 @@ typedef struct {
  * @brief Device descriptor for LSM303DLHC sensors
  */
 typedef struct {
-    i2c_t i2c;              /**< I2C device                  */
-    uint8_t acc_address;    /**< accelerometer's I2C address */
-    uint8_t mag_address;    /**< magnetometer's I2C address  */
-    gpio_t  acc_pin;        /**< accelerometer's data ready pin */
-    gpio_t  mag_pin;        /**< magnetometer's data ready pin  */
+    i2c_t i2c;                          /**< I2C device                  */
+    uint8_t acc_address;                /**< accelerometer's I2C address */
+    uint8_t mag_address;                /**< magnetometer's I2C address  */
+    gpio_t  acc_pin;                    /**< accelerometer's data ready pin */
+    gpio_t  mag_pin;                    /**< magnetometer's data ready pin  */
+    lsm303dlhc_acc_scale_t acc_scale;   /**< accelerometer scale factor */
+    lsm303dlhc_mag_gain_t mag_gain;     /**< magnetometer gain */
 } lsm303dlhc_t;
 
 /**
@@ -159,7 +161,7 @@ int lsm303dlhc_init(lsm303dlhc_t *dev, i2c_t i2c, gpio_t acc_pin, gpio_t mag_pin
  *                          +- 2g   |  1*10^-3
  *                          +- 4g   |  2*10^-3
  *                          +- 8g   |  4*10^-3
- *                          +-16g   | 12*10^-3
+ *                          +-16g   |  8*10^-3
  *
  * @param[in]  dev      device descriptor of an LSM303DLHC device
  * @param[out] data     the measured accelerometer data

drivers/lsm303dlhc/lsm303dlhc.c

@@ -41,6 +41,8 @@ int lsm303dlhc_init(lsm303dlhc_t *dev, i2c_t i2c, gpio_t acc_pin, gpio_t mag_pin
     dev->mag_address = mag_address;
     dev->acc_pin     = acc_pin;
     dev->mag_pin     = mag_pin;
+    dev->acc_scale   = acc_scale;
+    dev->mag_gain    = mag_gain;
 
     /* Acquire exclusive access to the bus. */
     i2c_acquire(dev->i2c);

drivers/lsm303dlhc/lsm303dlhc_saul.c

@@ -27,8 +27,15 @@ static int read_acc(void *dev, phydat_t *res)
 {
     lsm303dlhc_t *d = (lsm303dlhc_t *)dev;
     lsm303dlhc_read_acc(d, (lsm303dlhc_3d_data_t *)res);
+
+    /* normalize result */
+    int fac = (1 << (d->acc_scale >> 4));
+    for (int i = 0; i < 3; i++) {
+        res->val[i] *= fac;
+    }
+
     res->unit = UNIT_G;
-    res->scale = 0;
+    res->scale = -3;
     return 3;
 }
 
@@ -36,8 +43,27 @@ static int read_mag(void *dev, phydat_t *res)
 {
     lsm303dlhc_t *d = (lsm303dlhc_t *)dev;
     lsm303dlhc_read_mag(d, (lsm303dlhc_3d_data_t *)res);
+
+    /* normalize results */
+    int gain;
+    switch (d->mag_gain) {
+        case LSM303DLHC_MAG_GAIN_1100_980_GAUSS: gain = 1100; break;
+        case LSM303DLHC_MAG_GAIN_855_760_GAUSS:  gain = 855;  break;
+        case LSM303DLHC_MAG_GAIN_670_600_GAUSS:  gain = 670;  break;
+        case LSM303DLHC_MAG_GAIN_450_400_GAUSS:  gain = 450;  break;
+        case LSM303DLHC_MAG_GAIN_400_355_GAUSS:  gain = 400;  break;
+        case LSM303DLHC_MAG_GAIN_330_295_GAUSS:  gain = 330;  break;
+        case LSM303DLHC_MAG_GAIN_230_205_GAUSS:  gain = 230;  break;
+        default: gain = 1000; break;
+    }
+    for (int i = 0; i < 3; i++) {
+        int32_t tmp = res->val[i] * 1000;
+        tmp /= gain;
+        res->val[i] = (int16_t)tmp;
+    }
+
     res->unit = UNIT_GS;
-    res->scale = 0;
+    res->scale = -3;
     return 3;
 }