2 * Copyright © 2009 Keith Packard <keithp@keithp.com>
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License as published by
6 * the Free Software Foundation; version 2 of the License.
8 * This program is distributed in the hope that it will be useful, but
9 * WITHOUT ANY WARRANTY; without even the implied warranty of
10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
11 * General Public License for more details.
13 * You should have received a copy of the GNU General Public License along
14 * with this program; if not, write to the Free Software Foundation, Inc.,
15 * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
18 #ifndef AO_FLIGHT_TEST
23 #error Please define HAS_ACCEL
27 #error Please define HAS_GPS
31 #error Please define HAS_USB
34 /* Main flight thread. */
36 __pdata enum ao_flight_state ao_flight_state; /* current flight state */
37 __pdata uint16_t ao_flight_tick; /* time of last data */
38 __pdata uint16_t ao_flight_prev_tick; /* time of previous data */
39 __xdata int16_t ao_ground_pres; /* startup pressure */
40 __pdata uint16_t ao_launch_tick; /* time of launch detect */
42 __pdata int16_t ao_ground_accel; /* startup acceleration */
46 * track min/max data over a long interval to detect
49 __pdata uint16_t ao_interval_end;
50 __pdata int16_t ao_interval_min_height;
51 __pdata int16_t ao_interval_max_height;
53 __data uint8_t ao_flight_adc;
54 __pdata int16_t ao_raw_pres;
55 __xdata uint8_t ao_flight_force_idle;
58 __pdata int16_t ao_raw_accel, ao_raw_accel_prev;
59 __pdata int16_t ao_accel_2g;
61 /* Accelerometer calibration
63 * We're sampling the accelerometer through a resistor divider which
64 * consists of 5k and 10k resistors. This multiplies the values by 2/3.
65 * That goes into the cc1111 A/D converter, which is running at 11 bits
66 * of precision with the bits in the MSB of the 16 bit value. Only positive
67 * values are used, so values should range from 0-32752 for 0-3.3V. The
68 * specs say we should see 40mV/g (uncalibrated), multiply by 2/3 for what
69 * the A/D converter sees (26.67 mV/g). We should see 32752/3300 counts/mV,
70 * for a final computation of:
72 * 26.67 mV/g * 32767/3300 counts/mV = 264.8 counts/g
74 * Zero g was measured at 16000 (we would expect 16384).
75 * Note that this value is only require to tell if the
76 * rocket is standing upright. Once that is determined,
77 * the value of the accelerometer is averaged for 100 samples
78 * to find the resting accelerometer value, which is used
79 * for all further flight computations
82 #define GRAVITY 9.80665
84 #define ACCEL_NOSE_UP (ao_accel_2g >> 2)
89 * Barometer calibration
91 * We directly sample the barometer. The specs say:
93 * Pressure range: 15-115 kPa
94 * Voltage at 115kPa: 2.82
95 * Output scale: 27mV/kPa
97 * If we want to detect launch with the barometer, we need
98 * a large enough bump to not be fooled by noise. At typical
99 * launch elevations (0-2000m), a 200Pa pressure change cooresponds
100 * to about a 20m elevation change. This is 5.4mV, or about 3LSB.
101 * As all of our calculations are done in 16 bits, we'll actually see a change
102 * of 16 times this though
104 * 27 mV/kPa * 32767 / 3300 counts/mV = 268.1 counts/kPa
107 /* We also have a clock, which can be used to sanity check things in
108 * case of other failures
111 #define BOOST_TICKS_MAX AO_SEC_TO_TICKS(15)
113 #define to_fix16(x) ((int16_t) ((x) * 65536.0 + 0.5))
114 #define to_fix32(x) ((int32_t) ((x) * 65536.0 + 0.5))
115 #define from_fix(x) ((x) >> 16)
117 #include "ao_kalman.h"
119 __pdata int16_t ao_ground_height;
120 __pdata int16_t ao_height;
121 __pdata int16_t ao_speed;
122 __pdata int16_t ao_accel;
123 __pdata int16_t ao_max_height;
125 static __pdata int32_t ao_k_height;
126 static __pdata int32_t ao_k_speed;
127 static __pdata int32_t ao_k_accel;
129 #define AO_K_STEP_100 to_fix16(0.01)
130 #define AO_K_STEP_2_2_100 to_fix16(0.00005)
132 #define AO_K_STEP_10 to_fix16(0.1)
133 #define AO_K_STEP_2_2_10 to_fix16(0.005)
136 * Above this height, the baro sensor doesn't work
138 #define AO_MAX_BARO_HEIGHT 12000
141 * Above this speed, baro measurements are unreliable
143 #define AO_MAX_BARO_SPEED 300
146 ao_kalman_predict(void)
148 #ifdef AO_FLIGHT_TEST
149 if (ao_flight_tick - ao_flight_prev_tick > 5) {
150 ao_k_height += ((int32_t) ao_speed * AO_K_STEP_10 +
151 (int32_t) ao_accel * AO_K_STEP_2_2_10) >> 4;
152 ao_k_speed += (int32_t) ao_accel * AO_K_STEP_10;
156 if (ao_flight_debug) {
157 printf ("predict speed %g + (%g * %g) = %g\n",
158 ao_k_speed / (65536.0 * 16.0), ao_accel / 16.0, AO_K_STEP_100 / 65536.0,
159 (ao_k_speed + (int32_t) ao_accel * AO_K_STEP_100) / (65536.0 * 16.0));
162 ao_k_height += ((int32_t) ao_speed * AO_K_STEP_100 +
163 (int32_t) ao_accel * AO_K_STEP_2_2_100) >> 4;
164 ao_k_speed += (int32_t) ao_accel * AO_K_STEP_100;
167 static __pdata int16_t ao_error_h;
168 static __pdata int16_t ao_raw_alt;
169 static __pdata int16_t ao_raw_height;
170 static __pdata int16_t ao_error_h_sq_avg;
173 ao_kalman_err_height(void)
176 int16_t height_distrust;
178 int16_t speed_distrust;
181 ao_error_h = ao_raw_height - (int16_t) (ao_k_height >> 16);
188 ao_error_h_sq_avg -= ao_error_h_sq_avg >> 4;
189 ao_error_h_sq_avg += (e * e) >> 4;
191 height_distrust = ao_raw_height - AO_MAX_BARO_HEIGHT;
193 speed_distrust = (ao_speed - AO_MS_TO_SPEED(AO_MAX_BARO_SPEED)) >> 4;
194 if (speed_distrust <= 0)
196 else if (speed_distrust > height_distrust)
197 height_distrust = speed_distrust;
199 if (height_distrust <= 0)
202 if (height_distrust) {
203 #ifdef AO_FLIGHT_TEST
204 int old_ao_error_h = ao_error_h;
206 if (height_distrust > 0x100)
207 height_distrust = 0x100;
208 ao_error_h = (int16_t) ((int32_t) ao_error_h * (0x100 - height_distrust)) >> 8;
209 #ifdef AO_FLIGHT_TEST
210 if (ao_flight_debug) {
211 printf("over height %g over speed %g distrust: %g height: error %d -> %d\n",
212 (double) (ao_raw_height - AO_MAX_BARO_HEIGHT),
213 (ao_speed - AO_MS_TO_SPEED(AO_MAX_BARO_SPEED)) / 16.0,
214 height_distrust / 256.0,
215 old_ao_error_h, ao_error_h);
222 ao_kalman_correct_baro(void)
224 ao_kalman_err_height();
225 #ifdef AO_FLIGHT_TEST
226 if (ao_flight_tick - ao_flight_prev_tick > 5) {
227 ao_k_height += (int32_t) AO_BARO_K0_10 * ao_error_h;
228 ao_k_speed += (int32_t) AO_BARO_K1_10 * ao_error_h;
229 ao_k_accel += (int32_t) AO_BARO_K2_10 * ao_error_h;
233 ao_k_height += (int32_t) AO_BARO_K0_100 * ao_error_h;
234 ao_k_speed += (int32_t) AO_BARO_K1_100 * ao_error_h;
235 ao_k_accel += (int32_t) AO_BARO_K2_100 * ao_error_h;
239 static __pdata int16_t ao_error_a;
240 static __pdata int32_t ao_accel_scale;
243 ao_kalman_err_accel(void)
247 accel = (ao_ground_accel - ao_raw_accel) * ao_accel_scale;
249 /* Can't use ao_accel here as it is the pre-prediction value still */
250 ao_error_a = (accel - ao_k_accel) >> 16;
254 ao_kalman_correct_both(void)
256 ao_kalman_err_height();
257 ao_kalman_err_accel();
259 #ifdef AO_FLIGHT_TEST
260 if (ao_flight_tick - ao_flight_prev_tick > 5) {
261 if (ao_flight_debug) {
262 printf ("correct speed %g + (%g * %g) + (%g * %g) = %g\n",
263 ao_k_speed / (65536.0 * 16.0),
264 (double) ao_error_h, AO_BOTH_K10_10 / 65536.0,
265 (double) ao_error_a, AO_BOTH_K11_10 / 65536.0,
267 (int32_t) AO_BOTH_K10_10 * ao_error_h +
268 (int32_t) AO_BOTH_K11_10 * ao_error_a) / (65536.0 * 16.0));
271 (int32_t) AO_BOTH_K00_10 * ao_error_h +
272 (int32_t) (AO_BOTH_K01_10 >> 4) * ao_error_a;
274 ((int32_t) AO_BOTH_K10_10 << 4) * ao_error_h +
275 (int32_t) AO_BOTH_K11_10 * ao_error_a;
277 ((int32_t) AO_BOTH_K20_10 << 4) * ao_error_h +
278 (int32_t) AO_BOTH_K21_10 * ao_error_a;
281 if (ao_flight_debug) {
282 printf ("correct speed %g + (%g * %g) + (%g * %g) = %g\n",
283 ao_k_speed / (65536.0 * 16.0),
284 (double) ao_error_h, AO_BOTH_K10_100 / 65536.0,
285 (double) ao_error_a, AO_BOTH_K11_100 / 65536.0,
287 (int32_t) AO_BOTH_K10_100 * ao_error_h +
288 (int32_t) AO_BOTH_K11_100 * ao_error_a) / (65536.0 * 16.0));
292 (int32_t) AO_BOTH_K00_100 * ao_error_h +
293 (int32_t) AO_BOTH_K01_100 * ao_error_a;
295 (int32_t) AO_BOTH_K10_100 * ao_error_h +
296 (int32_t) AO_BOTH_K11_100 * ao_error_a;
298 (int32_t) AO_BOTH_K20_100 * ao_error_h +
299 (int32_t) AO_BOTH_K21_100 * ao_error_a;
304 ao_kalman_correct_accel(void)
306 ao_kalman_err_accel();
308 if (ao_flight_tick - ao_flight_prev_tick > 5) {
309 ao_k_height +=(int32_t) AO_ACCEL_K0_10 * ao_error_a;
310 ao_k_speed += (int32_t) AO_ACCEL_K1_10 * ao_error_a;
311 ao_k_accel += (int32_t) AO_ACCEL_K2_10 * ao_error_a;
314 ao_k_height += (int32_t) AO_ACCEL_K0_100 * ao_error_a;
315 ao_k_speed += (int32_t) AO_ACCEL_K1_100 * ao_error_a;
316 ao_k_accel += (int32_t) AO_ACCEL_K2_100 * ao_error_a;
319 #endif /* HAS_ACCEL */
321 __xdata int32_t ao_raw_pres_sum;
324 __xdata int32_t ao_raw_accel_sum;
327 /* Landing is detected by getting constant readings from both pressure and accelerometer
328 * for a fairly long time (AO_INTERVAL_TICKS)
330 #define AO_INTERVAL_TICKS AO_SEC_TO_TICKS(5)
332 #define abs(a) ((a) < 0 ? -(a) : (a))
337 __pdata static uint16_t nsamples = 0;
339 ao_flight_adc = ao_adc_head;
342 ao_raw_accel_prev = 0;
347 ao_wakeup(DATA_TO_XDATA(&ao_flight_adc));
348 ao_sleep(DATA_TO_XDATA(&ao_adc_head));
349 while (ao_flight_adc != ao_adc_head) {
350 __xdata struct ao_adc *ao_adc;
351 ao_flight_prev_tick = ao_flight_tick;
353 /* Capture a sample */
354 ao_adc = &ao_adc_ring[ao_flight_adc];
355 ao_flight_tick = ao_adc->tick;
356 ao_raw_pres = ao_adc->pres;
357 ao_raw_alt = ao_pres_to_altitude(ao_raw_pres);
358 ao_raw_height = ao_raw_alt - ao_ground_height;
360 ao_raw_accel = ao_adc->accel;
363 * Ok, the math here is a bit tricky.
365 * ao_raw_accel: ADC output for acceleration
366 * ao_accel_ref: ADC output for the 5V reference.
367 * ao_cook_accel: Corrected acceleration value
368 * Vcc: 3.3V supply to the CC1111
369 * Vac: 5V supply to the accelerometer
370 * accel: input voltage to accelerometer ADC pin
371 * ref: input voltage to 5V reference ADC pin
374 * Measured acceleration is ratiometric to Vcc:
377 * ------------ = -----
380 * Measured 5v reference is also ratiometric to Vcc:
383 * ------------ = -----
387 * ao_accel_ref = 32767 * (ref / Vcc)
389 * Acceleration is measured ratiometric to the 5V supply,
390 * so what we want is:
392 * ao_cook_accel accel
393 * ------------- = -----
402 * = ------------ * ------------
405 * Multiply through by 32767:
407 * ao_raw_accel * 32767
408 * ao_cook_accel = --------------------
411 * Now, the tricky part. Getting this to compile efficiently
412 * and keeping all of the values in-range.
414 * First off, we need to use a shift of 16 instead of * 32767 as SDCC
415 * does the obvious optimizations for byte-granularity shifts:
417 * ao_cook_accel = (ao_raw_accel << 16) / ao_accel_ref
419 * Next, lets check our input ranges:
421 * 0 <= ao_raw_accel <= 0x7fff (singled ended ADC conversion)
422 * 0x7000 <= ao_accel_ref <= 0x7fff (the 5V ref value is close to 0x7fff)
424 * Plugging in our input ranges, we get an output range of 0 - 0x12490,
425 * which is 17 bits. That won't work. If we take the accel ref and shift
426 * by a bit, we'll change its range:
428 * 0xe000 <= ao_accel_ref<<1 <= 0xfffe
430 * ao_cook_accel = (ao_raw_accel << 16) / (ao_accel_ref << 1)
432 * Now the output range is 0 - 0x9248, which nicely fits in 16 bits. It
433 * is, however, one bit too large for our signed computations. So, we
434 * take the result and shift that by a bit:
436 * ao_cook_accel = ((ao_raw_accel << 16) / (ao_accel_ref << 1)) >> 1
438 * This finally creates an output range of 0 - 0x4924. As the ADC only
439 * provides 11 bits of data, we haven't actually lost any precision,
440 * just dropped a bit of noise off the low end.
442 ao_raw_accel = (uint16_t) ((((uint32_t) ao_raw_accel << 16) / (ao_accel_ref[ao_flight_adc] << 1))) >> 1;
443 ao_adc->accel = ao_raw_accel;
447 if (ao_flight_state > ao_flight_idle) {
450 if (ao_flight_state <= ao_flight_coast) {
452 ao_kalman_correct_accel();
454 ao_kalman_correct_both();
458 ao_kalman_correct_baro();
459 ao_height = from_fix(ao_k_height);
460 ao_speed = from_fix(ao_k_speed);
461 ao_accel = from_fix(ao_k_accel);
462 if (ao_height > ao_max_height)
463 ao_max_height = ao_height;
465 ao_flight_adc = ao_adc_ring_next(ao_flight_adc);
468 switch (ao_flight_state) {
469 case ao_flight_startup:
473 * Collect 512 samples of acceleration and pressure
474 * data and average them to find the resting values
476 if (nsamples < 512) {
478 ao_raw_accel_sum += ao_raw_accel;
480 ao_raw_pres_sum += ao_raw_pres;
486 ao_ground_accel = ao_raw_accel_sum >> 9;
487 ao_accel_2g = ao_config.accel_minus_g - ao_config.accel_plus_g;
488 ao_accel_scale = to_fix32(GRAVITY * 2 * 16) / ao_accel_2g;
490 ao_ground_pres = ao_raw_pres_sum >> 9;
491 ao_ground_height = ao_pres_to_altitude(ao_ground_pres);
493 /* Check to see what mode we should go to.
494 * - Invalid mode if accel cal appears to be out
495 * - pad mode if we're upright,
496 * - idle mode otherwise
499 if (ao_config.accel_plus_g == 0 ||
500 ao_config.accel_minus_g == 0 ||
501 ao_ground_accel < ao_config.accel_plus_g - ACCEL_NOSE_UP ||
502 ao_ground_accel > ao_config.accel_minus_g + ACCEL_NOSE_UP)
504 /* Detected an accel value outside -1.5g to 1.5g
505 * (or uncalibrated values), so we go into invalid mode
507 ao_flight_state = ao_flight_invalid;
511 if (!ao_flight_force_idle
513 && ao_ground_accel < ao_config.accel_plus_g + ACCEL_NOSE_UP
517 /* Set pad mode - we can fly! */
518 ao_flight_state = ao_flight_pad;
520 /* Disable the USB controller in flight mode
526 /* Disable packet mode in pad state */
527 ao_packet_slave_stop();
529 /* Turn on telemetry system */
531 ao_telemetry_set_interval(AO_TELEMETRY_INTERVAL_PAD);
533 /* signal successful initialization by turning off the LED */
534 ao_led_off(AO_LED_RED);
537 ao_flight_state = ao_flight_idle;
539 /* signal successful initialization by turning off the LED */
540 ao_led_off(AO_LED_RED);
542 /* wakeup threads due to state change */
543 ao_wakeup(DATA_TO_XDATA(&ao_flight_state));
550 * barometer: > 20m vertical motion
552 * accelerometer: > 2g AND velocity > 5m/s
554 * The accelerometer should always detect motion before
555 * the barometer, but we use both to make sure this
556 * transition is detected. If the device
557 * doesn't have an accelerometer, then ignore the
558 * speed and acceleration as they are quite noisy
561 if (ao_height > AO_M_TO_HEIGHT(20)
563 || (ao_accel > AO_MSS_TO_ACCEL(20) &&
564 ao_speed > AO_MS_TO_SPEED(5))
568 ao_flight_state = ao_flight_boost;
569 ao_launch_tick = ao_flight_tick;
571 /* start logging data */
574 /* Increase telemetry rate */
575 ao_telemetry_set_interval(AO_TELEMETRY_INTERVAL_FLIGHT);
577 /* disable RDF beacon */
581 /* Record current GPS position by waking up GPS log tasks */
582 ao_wakeup(&ao_gps_data);
583 ao_wakeup(&ao_gps_tracking_data);
586 ao_wakeup(DATA_TO_XDATA(&ao_flight_state));
590 case ao_flight_boost:
594 * accelerometer: start to fall at > 1/4 G
596 * time: boost for more than 15 seconds
598 * Detects motor burn out by the switch from acceleration to
599 * deceleration, or by waiting until the maximum burn duration
600 * (15 seconds) has past.
602 if ((ao_accel < AO_MSS_TO_ACCEL(-2.5) && ao_height > AO_M_TO_HEIGHT(100)) ||
603 (int16_t) (ao_flight_tick - ao_launch_tick) > BOOST_TICKS_MAX)
605 ao_flight_state = ao_flight_fast;
606 ao_wakeup(DATA_TO_XDATA(&ao_flight_state));
612 * This is essentially the same as coast,
613 * but the barometer is being ignored as
614 * it may be unreliable.
616 if (ao_speed < AO_MS_TO_SPEED(AO_MAX_BARO_SPEED)) {
617 ao_flight_state = ao_flight_coast;
618 ao_wakeup(DATA_TO_XDATA(&ao_flight_state));
622 case ao_flight_coast:
624 /* apogee detect: coast to drogue deploy:
628 * Also make sure the model altitude is tracking
629 * the measured altitude reasonably closely; otherwise
630 * we're probably transsonic.
632 if (ao_speed < 0 && (ao_raw_alt >= AO_MAX_BARO_HEIGHT || ao_error_h_sq_avg < 100))
634 /* ignite the drogue charge */
635 ao_ignite(ao_igniter_drogue);
637 /* slow down the telemetry system */
638 ao_telemetry_set_interval(AO_TELEMETRY_INTERVAL_RECOVER);
641 * Start recording min/max height
642 * to figure out when the rocket has landed
645 /* initialize interval values */
646 ao_interval_end = ao_flight_tick + AO_INTERVAL_TICKS;
648 ao_interval_min_height = ao_interval_max_height = ao_height;
650 /* and enter drogue state */
651 ao_flight_state = ao_flight_drogue;
652 ao_wakeup(DATA_TO_XDATA(&ao_flight_state));
656 case ao_flight_drogue:
658 /* drogue to main deploy:
660 * barometer: reach main deploy altitude
662 * Would like to use the accelerometer for this test, but
663 * the orientation of the flight computer is unknown after
664 * drogue deploy, so we ignore it. Could also detect
665 * high descent rate using the pressure sensor to
666 * recognize drogue deploy failure and eject the main
667 * at that point. Perhaps also use the drogue sense lines
668 * to notice continutity?
670 if (ao_height <= ao_config.main_deploy)
672 ao_ignite(ao_igniter_main);
673 ao_flight_state = ao_flight_main;
674 ao_wakeup(DATA_TO_XDATA(&ao_flight_state));
677 /* fall through... */
680 /* drogue/main to land:
682 * barometer: altitude stable and within 1000m of the launch altitude
685 if (ao_height < ao_interval_min_height)
686 ao_interval_min_height = ao_height;
687 if (ao_height > ao_interval_max_height)
688 ao_interval_max_height = ao_height;
690 if ((int16_t) (ao_flight_tick - ao_interval_end) >= 0) {
691 if (ao_height < AO_M_TO_HEIGHT(1000) &&
692 ao_interval_max_height - ao_interval_min_height < AO_M_TO_HEIGHT(5))
694 ao_flight_state = ao_flight_landed;
696 /* turn off the ADC capture */
697 ao_timer_set_adc_interval(0);
698 /* Enable RDF beacon */
701 ao_wakeup(DATA_TO_XDATA(&ao_flight_state));
703 ao_interval_min_height = ao_interval_max_height = ao_height;
704 ao_interval_end = ao_flight_tick + AO_INTERVAL_TICKS;
707 case ao_flight_landed:
713 static __xdata struct ao_task flight_task;
718 ao_flight_state = ao_flight_startup;
719 ao_add_task(&flight_task, ao_flight, "flight");