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   1 /*
   2  * Copyright © 2013 Keith Packard <keithp@keithp.com>
   3  *
   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.
   7  *
   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.
  12  *
  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.
  16  */
  17
  18 #ifndef AO_FLIGHT_TEST
  19 #include <ao.h>
  20 #endif
  21 #include <ao_micropeak.h>
  22 #include <ao_log_micro.h>
  23
  24 uint32_t        pa;
  25 uint32_t        pa_ground;
  26 uint32_t        pa_min;
  27
  28 static void
  29 ao_microsample(void)
  30 {
  31         ao_pa_get();
  32         ao_microkalman_predict();
  33         ao_microkalman_correct();
  34 }
  35
  36 #define NUM_PA_HIST     (GROUND_AVG)
  37
  38 #define SKIP_PA_HIST(i,j)       (((i) + (j)) & (NUM_PA_HIST - 1))
  39
  40 static uint32_t pa_hist[NUM_PA_HIST];
  41
  42 void
  43 ao_microflight(void)
  44 {
  45         int16_t         sample_count;
  46         int16_t         log_count;
  47         uint16_t        time;
  48         uint32_t        pa_interval_min, pa_interval_max;
  49         int32_t         pa_diff;
  50         uint8_t         h;
  51         uint8_t         i;
  52         uint8_t         accel_lock = 0;
  53         uint32_t        pa_sum = 0;
  54
  55         /* Wait for motion, averaging values to get ground pressure */
  56
  57         time = ao_time();
  58         ao_pa_get();
  59         ao_microkalman_init();
  60         pa_ground = pa;
  61         sample_count = 0;
  62         h = 0;
  63         for (;;) {
  64                 time += SAMPLE_SLEEP;
  65                 if ((sample_count & 0x1f) == 0)
  66                         ao_led_on(AO_LED_REPORT);
  67                 ao_delay_until(time);
  68                 ao_microsample();
  69                 if ((sample_count & 0x1f) == 0)
  70                         ao_led_off(AO_LED_REPORT);
  71                 pa_hist[h] = pa;
  72                 h = SKIP_PA_HIST(h,1);
  73                 pa_diff = pa_ground - ao_pa;
  74
  75                 /* Check for a significant pressure change */
  76                 if (pa_diff > BOOST_DETECT)
  77                         break;
  78
  79                 if (sample_count < GROUND_AVG * 2) {
  80                         if (sample_count < GROUND_AVG)
  81                                 pa_sum += pa;
  82                         ++sample_count;
  83                 } else {
  84                         pa_ground = pa_sum >> GROUND_AVG_SHIFT;
  85                         pa_sum = 0;
  86                         sample_count = 0;
  87                 }
  88         }
  89
  90         /* Go back and find the last sample close to the ground */
  91         pa_min = pa_ground - LAND_DETECT;
  92         for (i = SKIP_PA_HIST(h,-2); i != SKIP_PA_HIST(h,2); i = SKIP_PA_HIST(i,-2)) {
  93                 if (pa_hist[i] >= pa_min)
  94                         break;
  95         }
  96
  97         /* Log the remaining samples so we get a complete history since leaving the ground */
  98 #if LOG_INTERVAL < NUM_PA_HIST
  99         for (; i != h; i = SKIP_PA_HIST(i,2))
 100 #endif
 101         {
 102                 pa = pa_hist[i];
 103                 ao_log_micro_data();
 104         }
 105
 106         /* Now sit around until the pressure is stable again and record the max */
 107
 108         sample_count = 0;
 109         log_count = 0;
 110         pa_min = ao_pa;
 111         pa_interval_min = ao_pa;
 112         pa_interval_max = ao_pa;
 113         for (;;) {
 114                 time += SAMPLE_SLEEP;
 115                 ao_delay_until(time);
 116                 if ((sample_count & 3) == 0)
 117                         ao_led_on(AO_LED_REPORT);
 118                 ao_microsample();
 119                 if ((sample_count & 3) == 0)
 120                         ao_led_off(AO_LED_REPORT);
 121                 if (log_count == LOG_INTERVAL - 1) {
 122                         ao_log_micro_data();
 123                         log_count = 0;
 124                 } else
 125                         log_count++;
 126
 127                 /* If accelerating upwards, don't look for min pressure */
 128                 if (ao_pa_accel < ACCEL_LOCK_PA)
 129                         accel_lock = ACCEL_LOCK_TIME;
 130                 else if (accel_lock)
 131                         --accel_lock;
 132                 else if (ao_pa < pa_min)
 133                         pa_min = ao_pa;
 134
 135                 if (sample_count == (GROUND_AVG - 1)) {
 136                         pa_diff = pa_interval_max - pa_interval_min;
 137
 138                         /* Check to see if the pressure is now stable */
 139                         if (pa_diff < LAND_DETECT)
 140                                 break;
 141                         sample_count = 0;
 142                         pa_interval_min = ao_pa;
 143                         pa_interval_max = ao_pa;
 144                 } else {
 145                         if (ao_pa < pa_interval_min)
 146                                 pa_interval_min = ao_pa;
 147                         if (ao_pa > pa_interval_max)
 148                                 pa_interval_max = ao_pa;
 149                         ++sample_count;
 150                 }
 151         }
 152 }