Switch from GPLv2 to GPLv2+

[fw/altos] / ao-tools / lib / cc-convert.c

diff --git a/ao-tools/lib/cc-convert.c b/ao-tools/lib/cc-convert.c
index ac6962ba254e6a82ef000f62631e2dafd172718e..0f7fa809ecd77864be20d5b866529f7c1c082308 100644 (file)
--- a/ao-tools/lib/cc-convert.c
+++ b/ao-tools/lib/cc-convert.c
@@ -3,7 +3,8 @@
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; version 2 of the License.
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
  *
  * This program is distributed in the hope that it will be useful, but
  * WITHOUT ANY WARRANTY; without even the implied warranty of
@@ -108,6 +109,29 @@ cc_altitude_to_pressure(double altitude)
    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 */
@@ -213,10 +237,19 @@ cc_accelerometer_to_acceleration(double accel, double ground_accel)
        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