add read measurement convenience method again

and use the method in the example

Author: LeonieFierz

example-usage/scd4x_i2c_example_usage.c

@@ -99,8 +99,8 @@ int main(void) {
     //
     bool data_ready = false;
     uint16_t co2_concentration = 0;
-    uint16_t temperature = 0;
-    uint16_t relative_humidity = 0;
+    int32_t temperature = 0;
+    int32_t relative_humidity = 0;
     uint16_t repetition = 0;
     for (repetition = 0; repetition < 50; repetition++) {
         //
@@ -124,17 +124,17 @@ int main(void) {
                 continue;
             }
         }
-        error = scd4x_read_measurement_raw(&co2_concentration, &temperature,
-                                           &relative_humidity);
+        error = scd4x_read_measurement(&co2_concentration, &temperature,
+                                       &relative_humidity);
         if (error != NO_ERROR) {
-            printf("error executing read_measurement_raw(): %i\n", error);
+            printf("error executing read_measurement(): %i\n", error);
             continue;
         }
         //
         // Print results in physical units.
         printf("CO2 concentration [ppm]: %u\n", co2_concentration);
-        printf("Temperature ticks: %u\n", temperature);
-        printf("Humidity ticks: %u\n", relative_humidity);
+        printf("Temperature [m°C] : %i\n", temperature);
+        printf("Humidity [mRH]: %i\n", relative_humidity);
     }
 
     return NO_ERROR;

scd4x_i2c.c

@@ -159,6 +159,20 @@ int16_t scd4x_read_measurement_raw(uint16_t* co2_concentration,
     return local_error;
 }
 
+int16_t scd4x_read_measurement(uint16_t* co2, int32_t* temperature_m_deg_c,
+                               int32_t* humidity_m_percent_rh) {
+    int16_t error;
+    uint16_t temperature;
+    uint16_t humidity;
+    error = scd4x_read_measurement_raw(co2, &temperature, &humidity);
+    if (error) {
+        return error;
+    }
+    *temperature_m_deg_c = ((21875 * (int32_t)temperature) >> 13) - 45000;
+    *humidity_m_percent_rh = ((12500 * (int32_t)humidity) >> 13);
+    return NO_ERROR;
+}
+
 int16_t scd4x_stop_periodic_measurement() {
     int16_t local_error = NO_ERROR;
     uint8_t* buffer_ptr = communication_buffer;

scd4x_i2c.h

@@ -195,6 +195,21 @@ int16_t scd4x_read_measurement_raw(uint16_t* co2_concentration,
                                    uint16_t* temperature,
                                    uint16_t* relative_humidity);
 
+/**
+ * @brief Read sensor output and convert to pyhsical unit.
+ *
+ * See @ref scd4x_read_measurement_raw() for more details.
+ *
+ * @param[out] co2 CO₂ concentration in ppm
+ * @param[out] temperature_m_deg_c Temperature in milli degrees celsius (°C *
+ * 1000)
+ * @param[out] humidity_m_percent_rh Relative humidity in milli percent RH
+ * (%RH * 1000)
+ * @return 0 on success, an error code otherwise
+ */
+int16_t scd4x_read_measurement(uint16_t* co2, int32_t* temperature_m_deg_c,
+                               int32_t* humidity_m_percent_rh);
+
 /**
  * @brief Stop periodic measurement to change the sensor configuration or to
  * save power.