return pressure;
}
+double
+cc_altitude_to_temperature(double altitude)
+{
+
+ double base_temperature = LAYER0_BASE_TEMPERATURE;
+ double temperature;
+
+ int layer_number; /* identifies layer in the atmosphere */
+ double delta_z; /* difference between two altitudes */
+
+ /* calculate the base temperature for the atmospheric layer
+ associated with the inputted altitude */
+ for(layer_number = 0; layer_number < NUMBER_OF_LAYERS - 1 && altitude > base_altitude[layer_number + 1]; layer_number++) {
+ delta_z = base_altitude[layer_number + 1] - base_altitude[layer_number];
+ base_temperature += delta_z * lapse_rate[layer_number];
+ }
+
+ /* calculate the pressure at the inputted altitude */
+ delta_z = altitude - base_altitude[layer_number];
+ temperature = base_temperature + lapse_rate[layer_number] * delta_z;
+
+ return temperature - 273.15;
+}
/* outputs the altitude associated with the given pressure. the altitude
returned is measured with respect to the mean sea level */
return (ground_accel - accel) / count_per_mss;
}
+/* Value for the CC1111 built-in temperature sensor
+ * Output voltage at 0°C = 0.755V
+ * Coefficient = 0.00247V/°C
+ * Reference voltage = 1.25V
+ *
+ * temp = ((value / 32767) * 1.25 - 0.755) / 0.00247
+ * = (value - 19791.268) / 32768 * 1.25 / 0.00247
+ */
+
double
cc_thermometer_to_temperature(double thermo)
{
- return ((thermo / 32767 * 3.3) - 0.5) / 0.01;
+ return (thermo - 19791.268) / 32728.0 * 1.25 / 0.00247;
}
double