diff options
Diffstat (limited to 'apps/sensors/sensors.cpp')
-rw-r--r-- | apps/sensors/sensors.cpp | 25 |
1 files changed, 13 insertions, 12 deletions
diff --git a/apps/sensors/sensors.cpp b/apps/sensors/sensors.cpp index d8d200ea9..c29910dcc 100644 --- a/apps/sensors/sensors.cpp +++ b/apps/sensors/sensors.cpp @@ -993,7 +993,7 @@ Sensors::adc_poll(struct sensor_combined_s &raw) /* look for battery channel */ for (unsigned i = 0; i < sizeof(buf_adc) / sizeof(buf_adc[0]); i++) { - + if (ret >= (int)sizeof(buf_adc[0])) { if (ADC_BATTERY_VOLTAGE_CHANNEL == buf_adc[i].am_channel) { @@ -1025,8 +1025,7 @@ Sensors::adc_poll(struct sensor_combined_s &raw) } else if (ADC_AIRSPEED_VOLTAGE_CHANNEL == buf_adc[i].am_channel) { /* calculate airspeed, raw is the difference from */ - - float voltage = buf_adc[i].am_data / 4096.0f; + float voltage = (float)(buf_adc[i].am_data ) * 3.3f / 4096.0f * 2.0f; //V_ref/4096 * (voltage divider factor) /** * The voltage divider pulls the signal down, only act on @@ -1034,21 +1033,23 @@ Sensors::adc_poll(struct sensor_combined_s &raw) */ if (voltage > 0.4f) { - float pres_raw = fabsf(voltage - (3.3f / 2.0f)); - float pres_mbar = pres_raw * (3.3f / 5.0f) * 10.0f; +// float pres_raw = fabsf(voltage - (3.3f / 2.0f)); +// float pres_mbar = pres_raw * (3.3f / 5.0f) * 10.0f; + //XXX depends on sensor used..., where are the above numbers from? + float diff_pres_pa = fabsf(voltage - 2.5f) * 1000.0f; //for MPXV7002DP //xxx: need an offset calibration - float airspeed_true = calc_true_airspeed(pres_mbar + _barometer.pressure, - _barometer.pressure, _barometer.temperature - 5.0f); + float airspeed_true = calc_true_airspeed(diff_pres_pa + _barometer.pressure*1e2f, + _barometer.pressure*1e2f, _barometer.temperature - 5.0f); //factor 1e2 for conversion from mBar to Pa // XXX HACK - true temperature is much less than indicated temperature in baro, // subtract 5 degrees in an attempt to account for the electrical upheating of the PCB - float airspeed_indicated = calc_indicated_airspeed(pres_mbar + _barometer.pressure, - _barometer.pressure, _barometer.temperature - 5.0f); - // XXX HACK + float airspeed_indicated = calc_indicated_airspeed(diff_pres_pa); + + //printf("voltage: %.4f, diff_pres_pa %.4f, v_ind %.4f, v_true %.4f\n", (double)voltage, (double)diff_pres_pa, (double)airspeed_indicated, (double)airspeed_true); _differential_pressure.timestamp = hrt_absolute_time(); _differential_pressure.static_pressure_mbar = _barometer.pressure; - _differential_pressure.differential_pressure_mbar = pres_mbar; + _differential_pressure.differential_pressure_mbar = diff_pres_pa*1e-2f; _differential_pressure.temperature_celcius = _barometer.temperature; _differential_pressure.indicated_airspeed_m_s = airspeed_indicated; _differential_pressure.true_airspeed_m_s = airspeed_true; @@ -1064,7 +1065,7 @@ Sensors::adc_poll(struct sensor_combined_s &raw) } _last_adc = hrt_absolute_time(); - break; + //break; } } } |