/* Main flight thread. */
__pdata enum ao_flight_state ao_flight_state; /* current flight state */
-__pdata uint16_t ao_flight_tick; /* time of last data */
-__pdata uint16_t ao_flight_prev_tick; /* time of previous data */
-__pdata int16_t ao_flight_pres; /* filtered pressure */
-__pdata int16_t ao_ground_pres; /* startup pressure */
-__pdata int16_t ao_min_pres; /* minimum recorded pressure */
__pdata uint16_t ao_launch_tick; /* time of launch detect */
-__pdata int16_t ao_main_pres; /* pressure to eject main */
-#if HAS_ACCEL
-__pdata int16_t ao_flight_accel; /* filtered acceleration */
-__pdata int16_t ao_ground_accel; /* startup acceleration */
-#endif
/*
* track min/max data over a long interval to detect
* resting
*/
__pdata uint16_t ao_interval_end;
-__pdata int16_t ao_interval_cur_min_pres;
-__pdata int16_t ao_interval_cur_max_pres;
-__pdata int16_t ao_interval_min_pres;
-__pdata int16_t ao_interval_max_pres;
-#if HAS_ACCEL
-__pdata int16_t ao_interval_cur_min_accel;
-__pdata int16_t ao_interval_cur_max_accel;
-__pdata int16_t ao_interval_min_accel;
-__pdata int16_t ao_interval_max_accel;
-#endif
+__pdata int16_t ao_interval_min_height;
+__pdata int16_t ao_interval_max_height;
-__data uint8_t ao_flight_adc;
-__pdata int16_t ao_raw_pres;
-__xdata uint8_t ao_flight_force_idle;
-
-#if HAS_ACCEL
-__pdata int16_t ao_raw_accel, ao_raw_accel_prev;
-__pdata int16_t ao_accel_2g;
-
-/* Accelerometer calibration
- *
- * We're sampling the accelerometer through a resistor divider which
- * consists of 5k and 10k resistors. This multiplies the values by 2/3.
- * That goes into the cc1111 A/D converter, which is running at 11 bits
- * of precision with the bits in the MSB of the 16 bit value. Only positive
- * values are used, so values should range from 0-32752 for 0-3.3V. The
- * specs say we should see 40mV/g (uncalibrated), multiply by 2/3 for what
- * the A/D converter sees (26.67 mV/g). We should see 32752/3300 counts/mV,
- * for a final computation of:
- *
- * 26.67 mV/g * 32767/3300 counts/mV = 264.8 counts/g
- *
- * Zero g was measured at 16000 (we would expect 16384).
- * Note that this value is only require to tell if the
- * rocket is standing upright. Once that is determined,
- * the value of the accelerometer is averaged for 100 samples
- * to find the resting accelerometer value, which is used
- * for all further flight computations
- */
-
-#define GRAVITY 9.80665
-/* convert m/s to velocity count */
-#define VEL_MPS_TO_COUNT(mps) (((int32_t) (((mps) / GRAVITY) * (AO_HERTZ/2))) * (int32_t) ao_accel_2g)
-
-#define ACCEL_NOSE_UP (ao_accel_2g >> 2)
-#define ACCEL_BOOST ao_accel_2g
-#define ACCEL_COAST (ao_accel_2g >> 3)
-#define ACCEL_INT_LAND (ao_accel_2g >> 3)
-#define ACCEL_VEL_MACH VEL_MPS_TO_COUNT(200)
-#define ACCEL_VEL_BOOST VEL_MPS_TO_COUNT(5)
-
-#endif
-
-/*
- * Barometer calibration
- *
- * We directly sample the barometer. The specs say:
- *
- * Pressure range: 15-115 kPa
- * Voltage at 115kPa: 2.82
- * Output scale: 27mV/kPa
- *
- * If we want to detect launch with the barometer, we need
- * a large enough bump to not be fooled by noise. At typical
- * launch elevations (0-2000m), a 200Pa pressure change cooresponds
- * to about a 20m elevation change. This is 5.4mV, or about 3LSB.
- * As all of our calculations are done in 16 bits, we'll actually see a change
- * of 16 times this though
- *
- * 27 mV/kPa * 32767 / 3300 counts/mV = 268.1 counts/kPa
- */
-
-#define BARO_kPa 268
-#define BARO_LAUNCH (BARO_kPa / 5) /* .2kPa, or about 20m */
-#define BARO_APOGEE (BARO_kPa / 10) /* .1kPa, or about 10m */
-#define BARO_COAST (BARO_kPa * 5) /* 5kpa, or about 500m */
-#define BARO_MAIN (BARO_kPa) /* 1kPa, or about 100m */
-#define BARO_INT_LAND (BARO_kPa / 20) /* .05kPa, or about 5m */
-#define BARO_LAND (BARO_kPa * 10) /* 10kPa or about 1000m */
+__xdata uint8_t ao_flight_force_idle;
/* We also have a clock, which can be used to sanity check things in
* case of other failures
#define BOOST_TICKS_MAX AO_SEC_TO_TICKS(15)
-#if HAS_ACCEL
-/* This value is scaled in a weird way. It's a running total of accelerometer
- * readings minus the ground accelerometer reading. That means it measures
- * velocity, and quite accurately too. As it gets updated 100 times a second,
- * it's scaled by 100
- */
-__pdata int32_t ao_flight_vel;
-__pdata int32_t ao_min_vel;
-__pdata int32_t ao_old_vel;
-__pdata int16_t ao_old_vel_tick;
-__xdata int32_t ao_raw_accel_sum;
-#endif
-
-__xdata int32_t ao_raw_pres_sum;
-
/* Landing is detected by getting constant readings from both pressure and accelerometer
* for a fairly long time (AO_INTERVAL_TICKS)
*/
void
ao_flight(void)
{
- __pdata static uint16_t nsamples = 0;
-
- ao_flight_adc = ao_adc_head;
- ao_raw_pres = 0;
-#if HAS_ACCEL
- ao_raw_accel_prev = 0;
- ao_raw_accel = 0;
-#endif
- ao_flight_tick = 0;
+ ao_sample_init();
+ ao_flight_state = ao_flight_startup;
for (;;) {
- ao_wakeup(DATA_TO_XDATA(&ao_flight_adc));
- ao_sleep(DATA_TO_XDATA(&ao_adc_head));
- while (ao_flight_adc != ao_adc_head) {
-#if HAS_ACCEL
- __pdata uint8_t ticks;
- __pdata int16_t ao_vel_change;
-#endif
- __xdata struct ao_adc *ao_adc;
- ao_flight_prev_tick = ao_flight_tick;
-
- /* Capture a sample */
- ao_adc = &ao_adc_ring[ao_flight_adc];
- ao_flight_tick = ao_adc->tick;
- ao_raw_pres = ao_adc->pres;
- ao_flight_pres -= ao_flight_pres >> 4;
- ao_flight_pres += ao_raw_pres >> 4;
-
-#if HAS_ACCEL
- ao_raw_accel = ao_adc->accel;
-#if HAS_ACCEL_REF
- /*
- * Ok, the math here is a bit tricky.
- *
- * ao_raw_accel: ADC output for acceleration
- * ao_accel_ref: ADC output for the 5V reference.
- * ao_cook_accel: Corrected acceleration value
- * Vcc: 3.3V supply to the CC1111
- * Vac: 5V supply to the accelerometer
- * accel: input voltage to accelerometer ADC pin
- * ref: input voltage to 5V reference ADC pin
- *
- *
- * Measured acceleration is ratiometric to Vcc:
- *
- * ao_raw_accel accel
- * ------------ = -----
- * 32767 Vcc
- *
- * Measured 5v reference is also ratiometric to Vcc:
- *
- * ao_accel_ref ref
- * ------------ = -----
- * 32767 Vcc
- *
- *
- * ao_accel_ref = 32767 * (ref / Vcc)
- *
- * Acceleration is measured ratiometric to the 5V supply,
- * so what we want is:
- *
- * ao_cook_accel accel
- * ------------- = -----
- * 32767 ref
- *
- *
- * accel Vcc
- * = ----- * ---
- * Vcc ref
- *
- * ao_raw_accel 32767
- * = ------------ * ------------
- * 32737 ao_accel_ref
- *
- * Multiply through by 32767:
- *
- * ao_raw_accel * 32767
- * ao_cook_accel = --------------------
- * ao_accel_ref
- *
- * Now, the tricky part. Getting this to compile efficiently
- * and keeping all of the values in-range.
- *
- * First off, we need to use a shift of 16 instead of * 32767 as SDCC
- * does the obvious optimizations for byte-granularity shifts:
- *
- * ao_cook_accel = (ao_raw_accel << 16) / ao_accel_ref
- *
- * Next, lets check our input ranges:
- *
- * 0 <= ao_raw_accel <= 0x7fff (singled ended ADC conversion)
- * 0x7000 <= ao_accel_ref <= 0x7fff (the 5V ref value is close to 0x7fff)
- *
- * Plugging in our input ranges, we get an output range of 0 - 0x12490,
- * which is 17 bits. That won't work. If we take the accel ref and shift
- * by a bit, we'll change its range:
- *
- * 0xe000 <= ao_accel_ref<<1 <= 0xfffe
- *
- * ao_cook_accel = (ao_raw_accel << 16) / (ao_accel_ref << 1)
- *
- * Now the output range is 0 - 0x9248, which nicely fits in 16 bits. It
- * is, however, one bit too large for our signed computations. So, we
- * take the result and shift that by a bit:
- *
- * ao_cook_accel = ((ao_raw_accel << 16) / (ao_accel_ref << 1)) >> 1
- *
- * This finally creates an output range of 0 - 0x4924. As the ADC only
- * provides 11 bits of data, we haven't actually lost any precision,
- * just dropped a bit of noise off the low end.
- */
- ao_raw_accel = (uint16_t) ((((uint32_t) ao_raw_accel << 16) / (ao_accel_ref[ao_flight_adc] << 1))) >> 1;
- ao_adc->accel = ao_raw_accel;
-#endif
- ao_flight_accel -= ao_flight_accel >> 4;
- ao_flight_accel += ao_raw_accel >> 4;
- /* Update velocity
- *
- * The accelerometer is mounted so that
- * acceleration yields negative values
- * while deceleration yields positive values,
- * so subtract instead of add.
- */
- ticks = ao_flight_tick - ao_flight_prev_tick;
- ao_vel_change = ao_ground_accel - (((ao_raw_accel + 1) >> 1) + ((ao_raw_accel_prev + 1) >> 1));
- ao_raw_accel_prev = ao_raw_accel;
-
- /* one is a common interval */
- if (ticks == 1)
- ao_flight_vel += (int32_t) ao_vel_change;
- else
- ao_flight_vel += (int32_t) ao_vel_change * (int32_t) ticks;
-#endif
-
- ao_flight_adc = ao_adc_ring_next(ao_flight_adc);
- }
-
- if (ao_flight_pres < ao_min_pres)
- ao_min_pres = ao_flight_pres;
-#if HAS_ACCEL
- if (ao_flight_vel >= 0) {
- if (ao_flight_vel < ao_min_vel)
- ao_min_vel = ao_flight_vel;
- } else {
- if (-ao_flight_vel < ao_min_vel)
- ao_min_vel = -ao_flight_vel;
- }
-#endif
+ /*
+ * Process ADC samples, just looping
+ * until the sensors are calibrated.
+ */
+ if (!ao_sample())
+ continue;
switch (ao_flight_state) {
case ao_flight_startup:
- /* startup state:
- *
- * Collect 512 samples of acceleration and pressure
- * data and average them to find the resting values
- */
- if (nsamples < 512) {
-#if HAS_ACCEL
- ao_raw_accel_sum += ao_raw_accel;
-#endif
- ao_raw_pres_sum += ao_raw_pres;
- ++nsamples;
- continue;
- }
-#if HAS_ACCEL
- ao_ground_accel = ao_raw_accel_sum >> 9;
-#endif
- ao_ground_pres = ao_raw_pres_sum >> 9;
- ao_min_pres = ao_ground_pres;
- ao_config_get();
- ao_main_pres = ao_altitude_to_pres(ao_pres_to_altitude(ao_ground_pres) + ao_config.main_deploy);
-#if HAS_ACCEL
- ao_accel_2g = ao_config.accel_minus_g - ao_config.accel_plus_g;
- ao_flight_vel = 0;
- ao_min_vel = 0;
- ao_old_vel = ao_flight_vel;
- ao_old_vel_tick = ao_flight_tick;
-#endif
-
/* Check to see what mode we should go to.
* - Invalid mode if accel cal appears to be out
* - pad mode if we're upright,
* - idle mode otherwise
*/
- ao_config_get();
#if HAS_ACCEL
if (ao_config.accel_plus_g == 0 ||
ao_config.accel_minus_g == 0 ||
- ao_flight_accel < ao_config.accel_plus_g - ACCEL_NOSE_UP ||
- ao_flight_accel > ao_config.accel_minus_g + ACCEL_NOSE_UP)
+ ao_ground_accel < ao_config.accel_plus_g - ACCEL_NOSE_UP ||
+ ao_ground_accel > ao_config.accel_minus_g + ACCEL_NOSE_UP)
{
/* Detected an accel value outside -1.5g to 1.5g
* (or uncalibrated values), so we go into invalid mode
*/
ao_flight_state = ao_flight_invalid;
- /* Allow packet mode in invalid flight state,
- * Still need to be able to fix the problem!
- */
- ao_packet_slave_start();
} else
#endif
if (!ao_flight_force_idle
#if HAS_ACCEL
- && ao_flight_accel < ao_config.accel_plus_g + ACCEL_NOSE_UP
+ && ao_ground_accel < ao_config.accel_plus_g + ACCEL_NOSE_UP
#endif
)
{
/* Set pad mode - we can fly! */
ao_flight_state = ao_flight_pad;
-
#if HAS_USB
/* Disable the USB controller in flight mode
* to save power
*/
ao_usb_disable();
#endif
+
+ /* Disable packet mode in pad state */
+ ao_packet_slave_stop();
+
/* Turn on telemetry system */
ao_rdf_set(1);
ao_telemetry_set_interval(AO_TELEMETRY_INTERVAL_PAD);
/* Set idle mode */
ao_flight_state = ao_flight_idle;
- /* Turn on packet system in idle mode */
- ao_packet_slave_start();
-
/* signal successful initialization by turning off the LED */
ao_led_off(AO_LED_RED);
}
break;
case ao_flight_pad:
-#if HAS_ACCEL
- /* Trim velocity
- *
- * Once a second, remove any velocity from
- * a second ago
- */
- if ((int16_t) (ao_flight_tick - ao_old_vel_tick) >= AO_SEC_TO_TICKS(1)) {
- ao_old_vel_tick = ao_flight_tick;
- ao_flight_vel -= ao_old_vel;
- ao_old_vel = ao_flight_vel;
- }
-#endif
/* pad to boost:
*
- * accelerometer: > 2g AND velocity > 5m/s
- * OR
* barometer: > 20m vertical motion
+ * OR
+ * accelerometer: > 2g AND velocity > 5m/s
*
* The accelerometer should always detect motion before
* the barometer, but we use both to make sure this
- * transition is detected
+ * transition is detected. If the device
+ * doesn't have an accelerometer, then ignore the
+ * speed and acceleration as they are quite noisy
+ * on the pad.
*/
- if (
+ if (ao_height > AO_M_TO_HEIGHT(20)
#if HAS_ACCEL
- (ao_flight_accel < ao_ground_accel - ACCEL_BOOST &&
- ao_flight_vel > ACCEL_VEL_BOOST) ||
+ || (ao_accel > AO_MSS_TO_ACCEL(20) &&
+ ao_speed > AO_MS_TO_SPEED(5))
#endif
- ao_flight_pres < ao_ground_pres - BARO_LAUNCH)
+ )
{
-#if HAS_ACCEL
ao_flight_state = ao_flight_boost;
-#else
- ao_flight_state = ao_flight_coast;
-#endif
- ao_launch_tick = ao_flight_tick;
+ ao_launch_tick = ao_sample_tick;
/* start logging data */
ao_log_start();
break;
}
break;
-#if HAS_ACCEL
case ao_flight_boost:
/* boost to fast:
* deceleration, or by waiting until the maximum burn duration
* (15 seconds) has past.
*/
- if (ao_flight_accel > ao_ground_accel + ACCEL_COAST ||
- (int16_t) (ao_flight_tick - ao_launch_tick) > BOOST_TICKS_MAX)
+ if ((ao_accel < AO_MSS_TO_ACCEL(-2.5) && ao_height > AO_M_TO_HEIGHT(100)) ||
+ (int16_t) (ao_sample_tick - ao_launch_tick) > BOOST_TICKS_MAX)
{
+#if HAS_ACCEL
ao_flight_state = ao_flight_fast;
+#else
+ ao_flight_state = ao_flight_coast;
+#endif
ao_wakeup(DATA_TO_XDATA(&ao_flight_state));
break;
}
break;
+#if HAS_ACCEL
case ao_flight_fast:
-
- /* fast to coast:
- *
- * accelerometer: integrated velocity < 200 m/s
- * OR
- * barometer: fall at least 500m from max altitude
- *
- * This extra state is required to avoid mis-detecting
- * apogee due to mach transitions.
- *
- * XXX this is essentially a single-detector test
- * as the 500m altitude change would likely result
- * in a loss of the rocket. More data on precisely
- * how big a pressure change the mach transition
- * generates would be useful here.
+ /*
+ * This is essentially the same as coast,
+ * but the barometer is being ignored as
+ * it may be unreliable.
*/
- if (ao_flight_vel < ACCEL_VEL_MACH ||
- ao_flight_pres > ao_min_pres + BARO_COAST)
+ if (ao_speed < AO_MS_TO_SPEED(AO_MAX_BARO_SPEED))
{
- /* set min velocity to current velocity for
- * apogee detect
- */
- ao_min_vel = abs(ao_flight_vel);
ao_flight_state = ao_flight_coast;
ao_wakeup(DATA_TO_XDATA(&ao_flight_state));
+ break;
}
break;
#endif
/* apogee detect: coast to drogue deploy:
*
- * barometer: fall at least 10m
+ * speed: < 0
*
- * It would be nice to use the accelerometer
- * to detect apogee as well, but tests have
- * shown that flights far from vertical would
- * grossly mis-detect apogee. So, for now,
- * we'll trust to a single sensor for this test
+ * Also make sure the model altitude is tracking
+ * the measured altitude reasonably closely; otherwise
+ * we're probably transsonic.
*/
- if (ao_flight_pres > ao_min_pres + BARO_APOGEE)
+ if (ao_speed < 0
+#if !HAS_ACCEL
+ && (ao_sample_alt >= AO_MAX_BARO_HEIGHT || ao_error_h_sq_avg < 100)
+#endif
+ )
{
/* ignite the drogue charge */
ao_ignite(ao_igniter_drogue);
/* slow down the telemetry system */
ao_telemetry_set_interval(AO_TELEMETRY_INTERVAL_RECOVER);
- /* slow down the ADC sample rate */
- ao_timer_set_adc_interval(10);
+ /* Turn the RDF beacon back on */
+ ao_rdf_set(1);
/*
- * Start recording min/max accel and pres for a while
+ * Start recording min/max height
* to figure out when the rocket has landed
*/
- /* Set the 'last' limits to max range to prevent
- * early resting detection
- */
-#if HAS_ACCEL
- ao_interval_min_accel = 0;
- ao_interval_max_accel = 0x7fff;
-#endif
- ao_interval_min_pres = 0;
- ao_interval_max_pres = 0x7fff;
/* initialize interval values */
- ao_interval_end = ao_flight_tick + AO_INTERVAL_TICKS;
+ ao_interval_end = ao_sample_tick + AO_INTERVAL_TICKS;
- ao_interval_cur_min_pres = ao_interval_cur_max_pres = ao_flight_pres;
-#if HAS_ACCEL
- ao_interval_cur_min_accel = ao_interval_cur_max_accel = ao_flight_accel;
-#endif
+ ao_interval_min_height = ao_interval_max_height = ao_height;
/* and enter drogue state */
ao_flight_state = ao_flight_drogue;
* at that point. Perhaps also use the drogue sense lines
* to notice continutity?
*/
- if (ao_flight_pres >= ao_main_pres)
+ if (ao_height <= ao_config.main_deploy)
{
ao_ignite(ao_igniter_main);
ao_flight_state = ao_flight_main;
/* drogue/main to land:
*
- * accelerometer: value stable
- * AND
* barometer: altitude stable and within 1000m of the launch altitude
*/
- if (ao_flight_pres < ao_interval_cur_min_pres)
- ao_interval_cur_min_pres = ao_flight_pres;
- if (ao_flight_pres > ao_interval_cur_max_pres)
- ao_interval_cur_max_pres = ao_flight_pres;
-#if HAS_ACCEL
- if (ao_flight_accel < ao_interval_cur_min_accel)
- ao_interval_cur_min_accel = ao_flight_accel;
- if (ao_flight_accel > ao_interval_cur_max_accel)
- ao_interval_cur_max_accel = ao_flight_accel;
-#endif
-
- if ((int16_t) (ao_flight_tick - ao_interval_end) >= 0) {
- ao_interval_max_pres = ao_interval_cur_max_pres;
- ao_interval_min_pres = ao_interval_cur_min_pres;
- ao_interval_cur_min_pres = ao_interval_cur_max_pres = ao_flight_pres;
-#if HAS_ACCEL
- ao_interval_max_accel = ao_interval_cur_max_accel;
- ao_interval_min_accel = ao_interval_cur_min_accel;
- ao_interval_cur_min_accel = ao_interval_cur_max_accel = ao_flight_accel;
-#endif
- ao_interval_end = ao_flight_tick + AO_INTERVAL_TICKS;
+ if (ao_height < ao_interval_min_height)
+ ao_interval_min_height = ao_height;
+ if (ao_height > ao_interval_max_height)
+ ao_interval_max_height = ao_height;
- if (
-#if HAS_ACCEL
- (uint16_t) (ao_interval_max_accel - ao_interval_min_accel) < (uint16_t) ACCEL_INT_LAND &&
-#endif
- ao_flight_pres > ao_ground_pres - BARO_LAND &&
- (uint16_t) (ao_interval_max_pres - ao_interval_min_pres) < (uint16_t) BARO_INT_LAND)
+ if ((int16_t) (ao_sample_tick - ao_interval_end) >= 0) {
+ if (ao_height < AO_M_TO_HEIGHT(1000) &&
+ ao_interval_max_height - ao_interval_min_height < AO_M_TO_HEIGHT(5))
{
ao_flight_state = ao_flight_landed;
/* turn off the ADC capture */
ao_timer_set_adc_interval(0);
- /* Enable RDF beacon */
- ao_rdf_set(1);
ao_wakeup(DATA_TO_XDATA(&ao_flight_state));
}
+ ao_interval_min_height = ao_interval_max_height = ao_height;
+ ao_interval_end = ao_sample_tick + AO_INTERVAL_TICKS;
}
break;
case ao_flight_landed: