easymotor-v3: Fix pressure to adc conversion to use reference voltage

[fw/altos] / src / easymotor-v3 / ao_pins.h

diff --git a/src/easymotor-v3/ao_pins.h b/src/easymotor-v3/ao_pins.h
index 856c763946d1b6dcd7aedd15e0b1e2a661656e2b..b3be803e40cda84373735046ae2dc1a627ae345c 100644 (file)
--- a/src/easymotor-v3/ao_pins.h
+++ b/src/easymotor-v3/ao_pins.h
@@ -90,10 +90,6 @@
 
 #define AO_DATA_RING           32
 
-struct ao_adc {
-       int16_t                 v_batt;
-       int16_t                 motor_pressure;
-};
 
 #define AO_ADC_DUMP(p) \
        printf("tick: %5lu batt: %5d motor_pressure: %5d\n", \
@@ -152,10 +148,48 @@ struct ao_adc {
 #define HAS_IMU                        1
 #define USE_ADXL375_IMU                1
 
+#define HAS_KALMAN             0
+
 /* Motor pressure */
 #define HAS_MOTOR_PRESSURE     1
 #define ao_data_motor_pressure(packet) ((packet)->adc.motor_pressure)
 
 typedef int16_t        motor_pressure_t;
 
+/* want about 50psi, or 344kPa */
+
+#define AO_FULL_SCALE_PRESSURE         11031612        /* 1600psi */
+#define AO_BOOST_DETECT_PRESSURE       344000          /* 50psi */
+#define AO_QUIET_DETECT_PRESSURE       207000          /* 30psi */
+
+static inline int16_t ao_delta_pressure_to_adc(uint32_t pressure)
+{
+       static const double volts_base = 0.5;
+       static const double volts_max = 4.5;
+
+       /* 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 * 10.0/15.6;
+
+       /* 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)
+
+struct ao_adc {
+       int16_t                 v_batt;
+       int16_t                 motor_pressure;
+};
+
 #endif /* _AO_PINS_H_ */