- /* Wait for motion, averaging values to get ground pressure */
- time = ao_time();
- ao_pa_get();
- pa_avg = pa_ground = pa << FILTER_SHIFT;
- sample_count = 0;
- for (;;) {
- time += SAMPLE_SLEEP;
- if (sample_count == 0)
- ao_led_on(AO_LED_REPORT);
- ao_delay_until(time);
- ao_pa_get();
- if (sample_count == 0)
- ao_led_off(AO_LED_REPORT);
- pa_avg = pa_avg - (pa_avg >> FILTER_SHIFT) + pa;
- pa_diff = pa_ground - pa_avg;
-
- /* Check for a significant pressure change */
- if (pa_diff > (BOOST_DETECT << FILTER_SHIFT))
- break;
-
- if (sample_count < GROUND_AVG * 2) {
- if (sample_count < GROUND_AVG)
- pa_sum += pa;
- ++sample_count;
- } else {
- pa_ground = pa_sum >> (GROUND_AVG_SHIFT - FILTER_SHIFT);
- pa_sum = 0;
- sample_count = 0;
- }
- }
-
- pa_ground >>= FILTER_SHIFT;
-
- /* Now sit around until the pressure is stable again and record the max */