--- /dev/null
+/*
+ * Copyright © 2012 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_SAMPLE_H_
+#define _AO_SAMPLE_H_
+
+#include <ao_data.h>
+
+/*
+ * ao_sample.c
+ */
+
+/*
+ * 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
+ */
+
+/* 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
+ */
+
+/*
+ * Above this height, the baro sensor doesn't work
+ */
+#if HAS_MS5607
+#define AO_MAX_BARO_HEIGHT 30000
+#else
+#define AO_MAX_BARO_HEIGHT 12000
+#endif
+
+/*
+ * Above this speed, baro measurements are unreliable
+ */
+#define AO_MAX_BARO_SPEED 200
+
+#define ACCEL_NOSE_UP (ao_accel_2g >> 2)
+
+/*
+ * Speed and acceleration are scaled by 16 to provide a bit more
+ * resolution while still having reasonable range. Note that this
+ * limits speed to 2047m/s (around mach 6) and acceleration to
+ * 2047m/s² (over 200g)
+ */
+
+#define AO_M_TO_HEIGHT(m) ((int16_t) (m))
+#define AO_MS_TO_SPEED(ms) ((int16_t) ((ms) * 16))
+#define AO_MSS_TO_ACCEL(mss) ((int16_t) ((mss) * 16))
+
+extern __pdata uint16_t ao_sample_tick; /* time of last data */
+extern __data uint8_t ao_sample_adc; /* Ring position of last processed sample */
+extern __data uint8_t ao_sample_data; /* Ring position of last processed sample */
+
+#if HAS_BARO
+extern __pdata pres_t ao_sample_pres; /* most recent pressure sensor reading */
+extern __pdata alt_t ao_sample_alt; /* MSL of ao_sample_pres */
+extern __pdata alt_t ao_sample_height; /* AGL of ao_sample_pres */
+extern __pdata pres_t ao_ground_pres; /* startup pressure */
+extern __pdata alt_t ao_ground_height; /* MSL of ao_ground_pres */
+#endif
+
+#if HAS_ACCEL
+extern __pdata accel_t ao_sample_accel; /* most recent accel sensor reading */
+extern __pdata accel_t ao_ground_accel; /* startup acceleration */
+extern __pdata accel_t ao_accel_2g; /* factory accel calibration */
+extern __pdata int32_t ao_accel_scale; /* sensor to m/s² conversion */
+#endif
+#if HAS_GYRO
+extern __pdata accel_t ao_ground_accel_along;
+extern __pdata accel_t ao_ground_accel_across;
+extern __pdata accel_t ao_ground_accel_through;
+extern __pdata int32_t ao_ground_pitch; /* * 512 */
+extern __pdata int32_t ao_ground_yaw; /* * 512 */
+extern __pdata int32_t ao_ground_roll; /* * 512 */
+extern __pdata accel_t ao_sample_accel_along;
+extern __pdata accel_t ao_sample_accel_across;
+extern __pdata accel_t ao_sample_accel_through;
+extern __pdata gyro_t ao_sample_roll;
+extern __pdata gyro_t ao_sample_pitch;
+extern __pdata gyro_t ao_sample_yaw;
+extern __pdata angle_t ao_sample_orient;
+#endif
+
+void ao_sample_init(void);
+
+/* returns FALSE in preflight mode, TRUE in flight mode */
+uint8_t ao_sample(void);
+
+/*
+ * ao_kalman.c
+ */
+
+#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)
+
+extern __pdata int16_t ao_height; /* meters */
+extern __pdata int16_t ao_speed; /* m/s * 16 */
+extern __pdata int16_t ao_accel; /* m/s² * 16 */
+extern __xdata int16_t ao_max_height; /* max of ao_height */
+extern __xdata int16_t ao_avg_height; /* running average of height */
+
+extern __pdata int16_t ao_error_h;
+extern __pdata int16_t ao_error_h_sq_avg;
+
+#if HAS_ACCEL
+extern __pdata int16_t ao_error_a;
+#endif
+
+void ao_kalman(void);
+
+#endif /* _AO_SAMPLE_H_ */
projects / fw / altos / blobdiff