altos/easymotor: Move pressure conversion code to ao_motor_flight.c

[fw/altos] / src / kernel / ao_motor_flight.c

diff --git a/src/kernel/ao_motor_flight.c b/src/kernel/ao_motor_flight.c
index f47f59b393eb0f5adb0d545ceb1e564e5b8f29b8..6fa68831ea8b9350fcdc84130a33194051708ebd 100644 (file)
--- a/src/kernel/ao_motor_flight.c
+++ b/src/kernel/ao_motor_flight.c
@@ -52,6 +52,35 @@ static AO_TICK_TYPE  ao_interval_end;
 
 uint8_t                        ao_flight_force_idle;
 
+/* Compute ADC value change given a defined pressure change in Pa */
+
+static inline int16_t
+ao_delta_pressure_to_adc(uint32_t pressure)
+{
+       static const double volts_base = AO_PRESSURE_VOLTS_BASE;
+       static const double volts_max = AO_PRESSURE_VOLTS_MAX;
+
+       /* Compute change in voltage from the sensor */
+       double  volts = (double) pressure / AO_FULL_SCALE_PRESSURE * (volts_max - volts_base);
+
+       /* voltage divider in front of the ADC input to decivolts */
+       double  adc_dv = volts * (10.0 * (double) AO_PRESSURE_DIV_MINUS /
+                                 ((double) AO_PRESSURE_DIV_PLUS + (double) AO_PRESSURE_DIV_MINUS));
+
+       /* convert to ADC output value */
+       double  adc = adc_dv * AO_ADC_MAX / AO_ADC_REFERENCE_DV;
+
+       if (adc > AO_ADC_MAX)
+               adc = AO_ADC_MAX;
+       if (adc < 0)
+               adc = 0;
+
+       return (int16_t) adc;
+}
+
+#define AO_BOOST_DETECT                        ao_delta_pressure_to_adc(AO_BOOST_DETECT_PRESSURE)
+#define AO_QUIET_DETECT                        ao_delta_pressure_to_adc(AO_QUIET_DETECT_PRESSURE)
+
 /*
  * Landing is detected by getting constant readings from pressure sensor
  * for a fairly long time (AO_INTERVAL_TICKS), along with the max being