altos: Split up flight code into separate flight/sample/kalman bits

The flight code mashed together data processing, filtering and actual
flight managament into one giant pile. Split things up so that we
have:

 ao_sample.c: Sensor data processing. Reads the ring, handles calibration
 ao_kalman.c: Filter the data to track the accel/speed/height values
 ao_flight.c: Flight state management, specific to rocketry.

The plan is to re-use ao_sample.c and ao_kalman.c for hardware not
specifically designed for rocketry, like TeleNano.

Signed-off-by: Keith Packard <keithp@keithp.com>

1 files changed, 15 insertions, 437 deletions

diff --git a/src/ao_flight.c b/src/ao_flight.c
index 88f0544f..94fbf178 100644
--- a/src/ao_flight.c
+++ b/src/ao_flight.c
@@ -34,13 +34,7 @@
 /* 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 */
-__xdata int16_t			ao_ground_pres;		/* startup pressure */
 __pdata uint16_t		ao_launch_tick;		/* time of launch detect */
-#if HAS_ACCEL
-__pdata int16_t			ao_ground_accel;	/* startup acceleration */
-#endif
 
 /*
  * track min/max data over a long interval to detect
@@ -50,59 +44,7 @@ __pdata uint16_t		ao_interval_end;
 __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
-
-#define ACCEL_NOSE_UP	(ao_accel_2g >> 2)
-
-#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
- */
+__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
@@ -110,228 +52,6 @@ __pdata int16_t ao_accel_2g;
 
 #define BOOST_TICKS_MAX	AO_SEC_TO_TICKS(15)
 
-#define to_fix16(x) ((int16_t) ((x) * 65536.0 + 0.5))
-#define to_fix32(x) ((int32_t) ((x) * 65536.0 + 0.5))
-#define from_fix(x)	((x) >> 16)
-
-#include "ao_kalman.h"
-
-__pdata int16_t			ao_ground_height;
-__pdata int16_t			ao_height;
-__pdata int16_t			ao_speed;
-__pdata int16_t			ao_accel;
-__pdata int16_t			ao_max_height;
-
-static __pdata int32_t		ao_k_height;
-static __pdata int32_t		ao_k_speed;
-static __pdata int32_t		ao_k_accel;
-
-#define AO_K_STEP_100		to_fix16(0.01)
-#define AO_K_STEP_2_2_100	to_fix16(0.00005)
-
-#define AO_K_STEP_10		to_fix16(0.1)
-#define AO_K_STEP_2_2_10	to_fix16(0.005)
-
-/*
- * Above this height, the baro sensor doesn't work
- */
-#define AO_MAX_BARO_HEIGHT	12000
-
-/*
- * Above this speed, baro measurements are unreliable
- */
-#define AO_MAX_BARO_SPEED	200
-
-static void
-ao_kalman_predict(void)
-{
-#ifdef AO_FLIGHT_TEST
-	if (ao_flight_tick - ao_flight_prev_tick > 5) {
-		ao_k_height += ((int32_t) ao_speed * AO_K_STEP_10 +
-				(int32_t) ao_accel * AO_K_STEP_2_2_10) >> 4;
-		ao_k_speed += (int32_t) ao_accel * AO_K_STEP_10;
-
-		return;
-	}
-	if (ao_flight_debug) {
-		printf ("predict speed %g + (%g * %g) = %g\n",
-			ao_k_speed / (65536.0 * 16.0), ao_accel / 16.0, AO_K_STEP_100 / 65536.0,
-			(ao_k_speed + (int32_t) ao_accel * AO_K_STEP_100) / (65536.0 * 16.0));
-	}
-#endif
-	ao_k_height += ((int32_t) ao_speed * AO_K_STEP_100 +
-			(int32_t) ao_accel * AO_K_STEP_2_2_100) >> 4;
-	ao_k_speed += (int32_t) ao_accel * AO_K_STEP_100;
-}
-
-static __pdata int16_t ao_error_h;
-static __pdata int16_t ao_raw_alt;
-static __pdata int16_t ao_raw_height;
-static __pdata int16_t ao_error_h_sq_avg;
-
-static void
-ao_kalman_err_height(void)
-{
-	int16_t	e;
-	int16_t height_distrust;
-#if HAS_ACCEL
-	int16_t	speed_distrust;
-#endif
-
-	ao_error_h = ao_raw_height - (int16_t) (ao_k_height >> 16);
-
-	e = ao_error_h;
-	if (e < 0)
-		e = -e;
-	if (e > 127)
-		e = 127;
-#if HAS_ACCEL
-	ao_error_h_sq_avg -= ao_error_h_sq_avg >> 2;
-	ao_error_h_sq_avg += (e * e) >> 2;
-#else
-	ao_error_h_sq_avg -= ao_error_h_sq_avg >> 4;
-	ao_error_h_sq_avg += (e * e) >> 4;
-#endif
-
-	height_distrust = ao_raw_height - AO_MAX_BARO_HEIGHT;
-#if HAS_ACCEL
-	/* speed is stored * 16, but we need to ramp between 200 and 328, so
-	 * we want to multiply by 2. The result is a shift by 3.
-	 */
-	speed_distrust = (ao_speed - AO_MS_TO_SPEED(AO_MAX_BARO_SPEED)) >> (4 - 1);
-	if (speed_distrust <= 0)
-		speed_distrust = 0;
-	else if (speed_distrust > height_distrust)
-		height_distrust = speed_distrust;
-#endif
-	if (height_distrust <= 0)
-		height_distrust = 0;
-
-	if (height_distrust) {
-#ifdef AO_FLIGHT_TEST
-		int	old_ao_error_h = ao_error_h;
-#endif
-		if (height_distrust > 0x100)
-			height_distrust = 0x100;
-		ao_error_h = (int16_t) (((int32_t) ao_error_h * (0x100 - height_distrust)) >> 8);
-#ifdef AO_FLIGHT_TEST
-		if (ao_flight_debug) {
-			printf("over height %g over speed %g distrust: %g height: error %d -> %d\n",
-			       (double) (ao_raw_height - AO_MAX_BARO_HEIGHT),
-			       (ao_speed - AO_MS_TO_SPEED(AO_MAX_BARO_SPEED)) / 16.0,
-			       height_distrust / 256.0,
-			       old_ao_error_h, ao_error_h);
-		}
-#endif
-	}
-}
-
-static void
-ao_kalman_correct_baro(void)
-{
-	ao_kalman_err_height();
-#ifdef AO_FLIGHT_TEST
-	if (ao_flight_tick - ao_flight_prev_tick > 5) {
-		ao_k_height += (int32_t) AO_BARO_K0_10 * ao_error_h;
-		ao_k_speed  += (int32_t) AO_BARO_K1_10 * ao_error_h;
-		ao_k_accel  += (int32_t) AO_BARO_K2_10 * ao_error_h;
-		return;
-	}
-#endif
-	ao_k_height += (int32_t) AO_BARO_K0_100 * ao_error_h;
-	ao_k_speed  += (int32_t) AO_BARO_K1_100 * ao_error_h;
-	ao_k_accel  += (int32_t) AO_BARO_K2_100 * ao_error_h;
-}
-
-#if HAS_ACCEL
-static __pdata int16_t ao_error_a;
-static __pdata int32_t ao_accel_scale;
-
-static void
-ao_kalman_err_accel(void)
-{
-	int32_t	accel;
-
-	accel = (ao_ground_accel - ao_raw_accel) * ao_accel_scale;
-
-	/* Can't use ao_accel here as it is the pre-prediction value still */
-	ao_error_a = (accel - ao_k_accel) >> 16;
-}
-
-static void
-ao_kalman_correct_both(void)
-{
-	ao_kalman_err_height();
-	ao_kalman_err_accel();
-
-#ifdef AO_FLIGHT_TEST
-	if (ao_flight_tick - ao_flight_prev_tick > 5) {
-		if (ao_flight_debug) {
-			printf ("correct speed %g + (%g * %g) + (%g * %g) = %g\n",
-				ao_k_speed / (65536.0 * 16.0),
-				(double) ao_error_h, AO_BOTH_K10_10 / 65536.0,
-				(double) ao_error_a, AO_BOTH_K11_10 / 65536.0,
-				(ao_k_speed +
-				 (int32_t) AO_BOTH_K10_10 * ao_error_h +
-				 (int32_t) AO_BOTH_K11_10 * ao_error_a) / (65536.0 * 16.0));
-		}
-		ao_k_height +=
-			(int32_t) AO_BOTH_K00_10 * ao_error_h +
-			(int32_t) AO_BOTH_K01_10 * ao_error_a;
-		ao_k_speed +=
-			(int32_t) AO_BOTH_K10_10 * ao_error_h +
-			(int32_t) AO_BOTH_K11_10 * ao_error_a;
-		ao_k_accel +=
-			(int32_t) AO_BOTH_K20_10 * ao_error_h +
-			(int32_t) AO_BOTH_K21_10 * ao_error_a;
-		return;
-	}
-	if (ao_flight_debug) {
-		printf ("correct speed %g + (%g * %g) + (%g * %g) = %g\n",
-			ao_k_speed / (65536.0 * 16.0),
-			(double) ao_error_h, AO_BOTH_K10_100 / 65536.0,
-			(double) ao_error_a, AO_BOTH_K11_100 / 65536.0,
-			(ao_k_speed +
-			 (int32_t) AO_BOTH_K10_100 * ao_error_h +
-			 (int32_t) AO_BOTH_K11_100 * ao_error_a) / (65536.0 * 16.0));
-	}
-#endif
-	ao_k_height +=
-		(int32_t) AO_BOTH_K00_100 * ao_error_h +
-		(int32_t) AO_BOTH_K01_100 * ao_error_a;
-	ao_k_speed +=
-		(int32_t) AO_BOTH_K10_100 * ao_error_h +
-		(int32_t) AO_BOTH_K11_100 * ao_error_a;
-	ao_k_accel +=
-		(int32_t) AO_BOTH_K20_100 * ao_error_h +
-		(int32_t) AO_BOTH_K21_100 * ao_error_a;
-}
-
-#ifdef FORCE_ACCEL
-static void
-ao_kalman_correct_accel(void)
-{
-	ao_kalman_err_accel();
-
-	if (ao_flight_tick - ao_flight_prev_tick > 5) {
-		ao_k_height +=(int32_t) AO_ACCEL_K0_10 * ao_error_a;
-		ao_k_speed  += (int32_t) AO_ACCEL_K1_10 * ao_error_a;
-		ao_k_accel  += (int32_t) AO_ACCEL_K2_10 * ao_error_a;
-		return;
-	}
-	ao_k_height += (int32_t) AO_ACCEL_K0_100 * ao_error_a;
-	ao_k_speed  += (int32_t) AO_ACCEL_K1_100 * ao_error_a;
-	ao_k_accel  += (int32_t) AO_ACCEL_K2_100 * ao_error_a;
-}
-#endif
-#endif /* HAS_ACCEL */
-
-__xdata int32_t ao_raw_pres_sum;
-
-#ifdef HAS_ACCEL
-__xdata int32_t ao_raw_accel_sum;
-#endif
-
 /* Landing is detected by getting constant readings from both pressure and accelerometer
  * for a fairly long time (AO_INTERVAL_TICKS)
  */
@@ -342,162 +62,20 @@ __xdata int32_t ao_raw_accel_sum;
 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) {
-			__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_raw_alt = ao_pres_to_altitude(ao_raw_pres);
-			ao_raw_height = ao_raw_alt - ao_ground_height;
-#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
-#endif
 
-			if (ao_flight_state > ao_flight_idle) {
-				ao_kalman_predict();
-#if HAS_ACCEL
-				if (ao_flight_state <= ao_flight_coast) {
-#ifdef FORCE_ACCEL
-					ao_kalman_correct_accel();
-#else
-					ao_kalman_correct_both();
-#endif
-				} else
-#endif
-					ao_kalman_correct_baro();
-				ao_height = from_fix(ao_k_height);
-				ao_speed = from_fix(ao_k_speed);
-				ao_accel = from_fix(ao_k_accel);
-				if (ao_height > ao_max_height)
-					ao_max_height = ao_height;
-			}
-			ao_flight_adc = ao_adc_ring_next(ao_flight_adc);
-		}
+		/*
+		 * 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;
-			}
-			ao_config_get();
-#if HAS_ACCEL
-			ao_ground_accel = ao_raw_accel_sum >> 9;
-			ao_accel_2g = ao_config.accel_minus_g - ao_config.accel_plus_g;
-			ao_accel_scale = to_fix32(GRAVITY * 2 * 16) / ao_accel_2g;
-#endif
-			ao_ground_pres = ao_raw_pres_sum >> 9;
-			ao_ground_height = ao_pres_to_altitude(ao_ground_pres);
-
 			/* Check to see what mode we should go to.
 			 *  - Invalid mode if accel cal appears to be out
 			 *  - pad mode if we're upright,
@@ -574,7 +152,7 @@ ao_flight(void)
 				)
 			{
 				ao_flight_state = ao_flight_boost;
-				ao_launch_tick = ao_flight_tick;
+				ao_launch_tick = ao_sample_tick;
 
 				/* start logging data */
 				ao_log_start();
@@ -608,7 +186,7 @@ ao_flight(void)
 			 * (15 seconds) has past.
 			 */
 			if ((ao_accel < AO_MSS_TO_ACCEL(-2.5) && ao_height > AO_M_TO_HEIGHT(100)) ||
-			    (int16_t) (ao_flight_tick - ao_launch_tick) > BOOST_TICKS_MAX)
+			    (int16_t) (ao_sample_tick - ao_launch_tick) > BOOST_TICKS_MAX)
 			{
 #if HAS_ACCEL
 				ao_flight_state = ao_flight_fast;
@@ -646,7 +224,7 @@ ao_flight(void)
 			 */
 			if (ao_speed < 0
 #if !HAS_ACCEL
-			    && (ao_raw_alt >= AO_MAX_BARO_HEIGHT || ao_error_h_sq_avg < 100)
+			    && (ao_sample_alt >= AO_MAX_BARO_HEIGHT || ao_error_h_sq_avg < 100)
 #endif
 				)
 			{
@@ -662,7 +240,7 @@ ao_flight(void)
 				 */
 
 				/* initialize interval values */
-				ao_interval_end = ao_flight_tick + AO_INTERVAL_TICKS;
+				ao_interval_end = ao_sample_tick + AO_INTERVAL_TICKS;
 
 				ao_interval_min_height = ao_interval_max_height = ao_height;
 
@@ -706,7 +284,7 @@ ao_flight(void)
 			if (ao_height > ao_interval_max_height)
 				ao_interval_max_height = ao_height;
 
-			if ((int16_t) (ao_flight_tick - ao_interval_end) >= 0) {
+			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))
 				{
@@ -720,7 +298,7 @@ ao_flight(void)
 					ao_wakeup(DATA_TO_XDATA(&ao_flight_state));
 				}
 				ao_interval_min_height = ao_interval_max_height = ao_height;
-				ao_interval_end = ao_flight_tick + AO_INTERVAL_TICKS;
+				ao_interval_end = ao_sample_tick + AO_INTERVAL_TICKS;
 			}
 			break;
 		case ao_flight_landed: