// *************************************************************************************************
// @fn do_altitude_measurement
// @brief Perform single altitude measurement
// @param u8 filter Filter option
// @return none
// *************************************************************************************************
void do_altitude_measurement(u8 filter)
{
volatile u32 pressure;
// If sensor is not ready, skip data read
if ((PS_INT_IN & PS_INT_PIN) == 0)
return;
// Get temperature (format is *10 K) from sensor
if (bmp_used)
{
sAlt.temperature = bmp_ps_get_temp();
}
else
{
sAlt.temperature = cma_ps_get_temp();
}
// Get pressure (format is 1Pa) from sensor
if (bmp_used)
{
// Start sampling data in ultra low power mode
bmp_ps_write_register(BMP_085_CTRL_MEAS_REG, BMP_085_P_MEASURE);
// Get updated altitude
while ((PS_INT_IN & PS_INT_PIN) == 0) ;
pressure = bmp_ps_get_pa();
}
else
{
pressure = cma_ps_get_pa();
}
// Store measured pressure value
if (filter == FILTER_OFF) //sAlt.pressure == 0)
{
sAlt.pressure = pressure;
}
else
{
// Filter current pressure
pressure = (u32) ((pressure * 0.2) + (sAlt.pressure * 0.8));
// Store average pressure
sAlt.pressure = pressure;
}
// Convert pressure (Pa) and temperature (K) to altitude (m)
sAlt.altitude = conv_pa_to_meter(sAlt.pressure, sAlt.temperature);
}
// *************************************************************************************************
// @fn do_altitude_measurement
// @brief Perform single altitude measurement
// @param u8 filter Filter option
// @return none
// *************************************************************************************************
void do_altitude_measurement()
{
volatile uint32_t pressure;
// If sensor is not ready, skip data read
if ((PS_INT_IN & PS_INT_PIN) == 0)
return;
// Get temperature (format is *10 K) from sensor
if (bmp_used)
{
sAlt.temperature = bmp_ps_get_temp();
}
else
{
sAlt.temperature = cma_ps_get_temp();
}
// Get pressure (format is 1Pa) from sensor
if (bmp_used)
{
// Start sampling data in configurable power mode
bmp_ps_write_register(BMP_085_CTRL_MEAS_REG, BMP_085_P_MEASURE + (altPowerMode << 6));
// Get updated altitude
while ((PS_INT_IN & PS_INT_PIN) == 0) ;
pressure = bmp_ps_get_pa();
}
else
{
pressure = cma_ps_get_pa();
}
// Store measured pressure value
if(useFilter && sAlt.pressure){
// Filter only if there was a previous value (to get a good first value)
pressure = (u32) ((pressure * 0.7) + (sAlt.pressure * 0.3));
}
sAlt.pressure = pressure;
// Convert pressure (Pa) and temperature (K) to altitude (m)
sAlt.raw_altitude = conv_pa_to_meter(sAlt.pressure, sAlt.temperature);
if(sAlt.raw_altitude > sAlt.raw_maxAltitude){
sAlt.raw_maxAltitude = sAlt.raw_altitude;
}
if(sAlt.raw_altitude < sAlt.raw_minAltitude){
sAlt.raw_minAltitude = sAlt.raw_altitude;
}
if((sAlt.raw_altitude > oldAccuAltitude) && (sAlt.raw_altitude - oldAccuAltitude > sAlt.accu_threshold)){
sAlt.accuClimbUp += sAlt.raw_altitude - oldAccuAltitude;
oldAccuAltitude = sAlt.raw_altitude;
}
if((sAlt.raw_altitude < oldAccuAltitude) && (oldAccuAltitude - sAlt.raw_altitude > sAlt.accu_threshold)){
sAlt.accuClimbDown -= oldAccuAltitude - sAlt.raw_altitude;
oldAccuAltitude = sAlt.raw_altitude;
}
sAlt.minAltitude = sAlt.raw_minAltitude - sAlt.altitude_offset;
sAlt.maxAltitude = sAlt.raw_maxAltitude - sAlt.altitude_offset;
sAlt.altitude = sAlt.raw_altitude - sAlt.altitude_offset;
// Update climb value. Calibration is irrelevant, as it is just a constant sum.
// We subtract first_pressure from the reading to get the numbers down to something
// that fits in 16 bits.
sAlt.history_pos = (sAlt.history_pos + 1) % ALT_HISTORY_LEN;
// Remove oldest value
sAlt.climb += sAlt.history[sAlt.history_pos];
// Add newest value
sAlt.history[sAlt.history_pos] = (pressure - sAlt.first_pressure);
sAlt.climb += sAlt.history[sAlt.history_pos];
// The time half a history ago now affects the climb with a different sign,
// so subtract twice
sAlt.climb -= 2 * sAlt.history[(sAlt.history_pos + ALT_HISTORY_LEN/2) % ALT_HISTORY_LEN];
}