+++ /dev/null
-/*
- * Copyright © 2011 Keith Packard <keithp@keithp.com>
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; version 2 of the License.
- *
- * This program is distributed in the hope that it will be useful, but
- * WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
- * General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License along
- * with this program; if not, write to the Free Software Foundation, Inc.,
- * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
- */
-
-#ifndef AO_FLIGHT_TEST
-#include "ao.h"
-#endif
-
-/*
- * Current sensor values
- */
-
-__pdata uint16_t ao_sample_tick; /* time of last data */
-__pdata int16_t ao_sample_pres;
-__pdata int16_t ao_sample_alt;
-__pdata int16_t ao_sample_height;
-#if HAS_ACCEL
-__pdata int16_t ao_sample_accel;
-#endif
-
-__data uint8_t ao_sample_adc;
-
-/*
- * Sensor calibration values
- */
-
-__pdata int16_t ao_ground_pres; /* startup pressure */
-__pdata int16_t ao_ground_height; /* MSL of ao_ground_pres */
-
-#if HAS_ACCEL
-__pdata int16_t ao_ground_accel; /* startup acceleration */
-__pdata int16_t ao_accel_2g; /* factory accel calibration */
-__pdata int32_t ao_accel_scale; /* sensor to m/s² conversion */
-#endif
-
-static __pdata uint8_t ao_preflight; /* in preflight mode */
-
-static __pdata uint16_t nsamples;
-__pdata int32_t ao_sample_pres_sum;
-#if HAS_ACCEL
-__pdata int32_t ao_sample_accel_sum;
-#endif
-
-static void
-ao_sample_preflight(void)
-{
- /* 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_sample_accel_sum += ao_sample_accel;
-#endif
- ao_sample_pres_sum += ao_sample_pres;
- ++nsamples;
- } else {
- ao_config_get();
-#if HAS_ACCEL
- ao_ground_accel = ao_sample_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_sample_pres_sum >> 9;
- ao_ground_height = ao_pres_to_altitude(ao_ground_pres);
- ao_preflight = FALSE;
- }
-}
-
-uint8_t
-ao_sample(void)
-{
- ao_wakeup(DATA_TO_XDATA(&ao_sample_adc));
- ao_sleep(DATA_TO_XDATA(&ao_adc_head));
- while (ao_sample_adc != ao_adc_head) {
- __xdata struct ao_adc *ao_adc;
-
- /* Capture a sample */
- ao_adc = &ao_adc_ring[ao_sample_adc];
- ao_sample_tick = ao_adc->tick;
- ao_sample_pres = ao_adc->pres;
- ao_sample_alt = ao_pres_to_altitude(ao_sample_pres);
- ao_sample_height = ao_sample_alt - ao_ground_height;
-#if HAS_ACCEL
- ao_sample_accel = ao_adc->accel;
-#if HAS_ACCEL_REF
- /*
- * Ok, the math here is a bit tricky.
- *
- * ao_sample_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_sample_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_sample_accel 32767
- * = ------------ * ------------
- * 32767 ao_accel_ref
- *
- * Multiply through by 32767:
- *
- * ao_sample_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_sample_accel << 16) / ao_accel_ref
- *
- * Next, lets check our input ranges:
- *
- * 0 <= ao_sample_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_sample_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_sample_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_sample_accel = (uint16_t) ((((uint32_t) ao_sample_accel << 16) / (ao_accel_ref[ao_sample_adc] << 1))) >> 1;
- if (ao_config.pad_orientation != AO_PAD_ORIENTATION_ANTENNA_UP)
- ao_sample_accel = 0x7fff - ao_sample_accel;
- ao_adc->accel = ao_sample_accel;
-#else
- if (ao_config.pad_orientation != AO_PAD_ORIENTATION_ANTENNA_UP) {
- ao_sample_accel = 0x7fff - ao_sample_accel;
- ao_adc->accel = ao_sample_accel;
- }
-#endif
-#endif
-
- if (ao_preflight)
- ao_sample_preflight();
- else
- ao_kalman();
- ao_sample_adc = ao_adc_ring_next(ao_sample_adc);
- }
- return !ao_preflight;
-}
-
-void
-ao_sample_init(void)
-{
- nsamples = 0;
- ao_sample_pres_sum = 0;
- ao_sample_pres = 0;
-#if HAS_ACCEL
- ao_sample_accel_sum = 0;
- ao_sample_accel = 0;
-#endif
- ao_sample_adc = ao_adc_head;
- ao_preflight = TRUE;
-}
projects / fw / altos / blobdiff