diff --git a/Makefile b/Makefile index 6501d287b2..0e3feab7bf 100644 --- a/Makefile +++ b/Makefile @@ -291,6 +291,7 @@ COMMON_SRC = build_config.c \ flight/pid.c \ flight/imu.c \ flight/mixer.c \ + flight/lowpass.c \ drivers/bus_i2c_soft.c \ drivers/serial.c \ drivers/sound_beeper.c \ diff --git a/src/main/config/config.c b/src/main/config/config.c index e2339cfed5..58f626410f 100755 --- a/src/main/config/config.c +++ b/src/main/config/config.c @@ -334,7 +334,7 @@ void resetMixerConfig(mixerConfig_t *mixerConfig) { mixerConfig->yaw_jump_prevention_limit = 200; #ifdef USE_SERVOS mixerConfig->tri_unarmed_servo = 1; - mixerConfig->servo_lowpass_freq = 400.0f; + mixerConfig->servo_lowpass_freq = 400; mixerConfig->servo_lowpass_enable = 0; #endif } diff --git a/src/main/flight/lowpass.c b/src/main/flight/lowpass.c new file mode 100755 index 0000000000..bb1b71c9d9 --- /dev/null +++ b/src/main/flight/lowpass.c @@ -0,0 +1,118 @@ +/* + * This file is part of Cleanflight. + * + * Cleanflight 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, either version 3 of the License, or + * (at your option) any later version. + * + * Cleanflight 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 Cleanflight. If not, see . + */ + +#include +#include +#include +#include + +#include "common/maths.h" +#include "flight/lowpass.h" + +//#define DEBUG_LOWPASS + +void generateLowpassCoeffs2(int16_t freq, lowpass_t *filter) +{ + float fixedScaler; + int i; + + // generates coefficients for a 2nd-order butterworth low-pass filter + float freqf = (float)freq*0.001f; + float omega = tan_approx((float)M_PI*freqf/2.0f); + float scaling = 1.0f / (omega*omega + 1.4142136f*omega + 1.0f); + + +#if defined(UNIT_TEST) && defined(DEBUG_LOWPASS) + printf("lowpass cutoff: %f, omega: %f\n", freqf, omega); +#endif + + filter->bf[0] = scaling * omega*omega; + filter->bf[1] = 2.0f * filter->bf[0]; + filter->bf[2] = filter->bf[0]; + + filter->af[0] = 1.0f; + filter->af[1] = scaling * (2.0f * omega*omega - 2.0f); + filter->af[2] = scaling * (omega*omega - 1.4142136f * omega + 1.0f); + + // Scale for fixed-point + filter->input_bias = 1500; // Typical servo range is 1500 +/- 500 + filter->input_shift = 16; + filter->coeff_shift = 24; + fixedScaler = (float)(1ULL << filter->coeff_shift); + for (i = 0; i < LOWPASS_NUM_COEF; i++) { + filter->a[i] = LPF_ROUND(filter->af[i] * fixedScaler); + filter->b[i] = LPF_ROUND(filter->bf[i] * fixedScaler); +#if defined(UNIT_TEST) && defined(DEBUG_LOWPASS) + printf("(%d) bf: %f af: %f b: %ld a: %ld\n", i, + filter->bf[i], filter->af[i], filter->b[i], filter->a[i]); +#endif + } + + filter->freq = freq; +} + +int32_t lowpassFixed(lowpass_t *filter, int32_t in, int16_t freq) +{ + int16_t coefIdx; + int64_t out; + int32_t in_s; + + // Check to see if cutoff frequency changed + if (freq != filter->freq) { + filter->init = false; + } + + // Initialize if needed + if (!filter->init) { + generateLowpassCoeffs2(freq, filter); + for (coefIdx = 0; coefIdx < LOWPASS_NUM_COEF; coefIdx++) { + filter->x[coefIdx] = (in - filter->input_bias) << filter->input_shift; + filter->y[coefIdx] = (in - filter->input_bias) << filter->input_shift; + } + filter->init = true; + } + + // Unbias input and scale + in_s = (in - filter->input_bias) << filter->input_shift; + + // Delays + for (coefIdx = LOWPASS_NUM_COEF-1; coefIdx > 0; coefIdx--) { + filter->x[coefIdx] = filter->x[coefIdx-1]; + filter->y[coefIdx] = filter->y[coefIdx-1]; + } + filter->x[0] = in_s; + + // Accumulate result + out = filter->x[0] * filter->b[0]; + for (coefIdx = 1; coefIdx < LOWPASS_NUM_COEF; coefIdx++) { + out -= filter->y[coefIdx] * filter->a[coefIdx]; + out += filter->x[coefIdx] * filter->b[coefIdx]; + } + + // Scale output by coefficient shift + out >>= filter->coeff_shift; + filter->y[0] = (int32_t)out; + + // Scale output by input shift and round + out = (out + (1 << (filter->input_shift-1))) >> filter->input_shift; + + // Reapply bias + out += filter->input_bias; + + return (int32_t)out; +} + diff --git a/src/main/flight/lowpass.h b/src/main/flight/lowpass.h new file mode 100644 index 0000000000..f1b57a315e --- /dev/null +++ b/src/main/flight/lowpass.h @@ -0,0 +1,41 @@ +/* + * This file is part of Cleanflight. + * + * Cleanflight 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, either version 3 of the License, or + * (at your option) any later version. + * + * Cleanflight 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 Cleanflight. If not, see . + */ + +#pragma once + + +#define LOWPASS_NUM_COEF 3 +#define LPF_ROUND(x) (x < 0 ? (x - 0.5f) : (x + 0.5f)) + +typedef struct lowpass_s { + bool init; + int16_t freq; // Normalized freq in 1/1000ths + float bf[LOWPASS_NUM_COEF]; + float af[LOWPASS_NUM_COEF]; + int64_t b[LOWPASS_NUM_COEF]; + int64_t a[LOWPASS_NUM_COEF]; + int16_t coeff_shift; + int16_t input_shift; + int32_t input_bias; + float xf[LOWPASS_NUM_COEF]; + float yf[LOWPASS_NUM_COEF]; + int32_t x[LOWPASS_NUM_COEF]; + int32_t y[LOWPASS_NUM_COEF]; +} lowpass_t; + +void generateLowpassCoeffs2(int16_t freq, lowpass_t *filter); +int32_t lowpassFixed(lowpass_t *filter, int32_t in, int16_t freq); diff --git a/src/main/flight/mixer.c b/src/main/flight/mixer.c index 68c3115e76..ff01a08439 100755 --- a/src/main/flight/mixer.c +++ b/src/main/flight/mixer.c @@ -19,7 +19,6 @@ #include #include #include -#include #include "platform.h" #include "debug.h" @@ -28,7 +27,6 @@ #include "common/axis.h" #include "common/maths.h" -#include "common/filter.h" #include "drivers/system.h" #include "drivers/pwm_output.h" @@ -36,7 +34,6 @@ #include "drivers/sensor.h" #include "drivers/accgyro.h" #include "drivers/system.h" -#include "drivers/gyro_sync.h" #include "rx/rx.h" @@ -51,6 +48,7 @@ #include "flight/failsafe.h" #include "flight/pid.h" #include "flight/imu.h" +#include "flight/lowpass.h" #include "config/runtime_config.h" #include "config/config.h" @@ -79,6 +77,7 @@ int16_t servo[MAX_SUPPORTED_SERVOS]; static int useServo; STATIC_UNIT_TESTED uint8_t servoCount; static servoParam_t *servoConf; +static lowpass_t lowpassFilters[MAX_SUPPORTED_SERVOS]; #endif static const motorMixer_t mixerQuadX[] = { @@ -925,8 +924,6 @@ void filterServos(void) { #ifdef USE_SERVOS int16_t servoIdx; - static bool servoFilterIsSet; - biquad_t servoFitlerState[MAX_SUPPORTED_SERVOS]; #if defined(MIXER_DEBUG) uint32_t startTime = micros(); @@ -934,11 +931,7 @@ void filterServos(void) if (mixerConfig->servo_lowpass_enable) { for (servoIdx = 0; servoIdx < MAX_SUPPORTED_SERVOS; servoIdx++) { - if (!servoFilterIsSet) { - BiQuadNewLpf(mixerConfig->servo_lowpass_freq, &servoFitlerState[servoIdx], targetLooptime); - servoFilterIsSet = true; - } - servo[servoIdx] = lrintf(applyBiQuadFilter((float) servo[servoIdx], &servoFitlerState[servoIdx])); + servo[servoIdx] = (int16_t)lowpassFixed(&lowpassFilters[servoIdx], servo[servoIdx], mixerConfig->servo_lowpass_freq); // Sanity check servo[servoIdx] = constrain(servo[servoIdx], servoConf[servoIdx].min, servoConf[servoIdx].max); diff --git a/src/main/io/serial_cli.c b/src/main/io/serial_cli.c index aae7a22524..db53f67724 100644 --- a/src/main/io/serial_cli.c +++ b/src/main/io/serial_cli.c @@ -620,7 +620,7 @@ const clivalue_t valueTable[] = { { "yaw_jump_prevention_limit", VAR_UINT16 | MASTER_VALUE, &masterConfig.mixerConfig.yaw_jump_prevention_limit, .config.minmax = { YAW_JUMP_PREVENTION_LIMIT_LOW, YAW_JUMP_PREVENTION_LIMIT_HIGH } }, #ifdef USE_SERVOS { "tri_unarmed_servo", VAR_INT8 | MASTER_VALUE | MODE_LOOKUP, &masterConfig.mixerConfig.tri_unarmed_servo, .config.lookup = { TABLE_OFF_ON } }, - { "servo_lowpass_freq", VAR_FLOAT | MASTER_VALUE, &masterConfig.mixerConfig.servo_lowpass_freq, .config.minmax = { 10, 400} }, + { "servo_lowpass_freq", VAR_INT16 | MASTER_VALUE, &masterConfig.mixerConfig.servo_lowpass_freq, .config.minmax = { 10, 400} }, { "servo_lowpass_enable", VAR_INT8 | MASTER_VALUE | MODE_LOOKUP, &masterConfig.mixerConfig.servo_lowpass_enable, .config.lookup = { TABLE_OFF_ON } }, #endif diff --git a/src/main/sensors/battery.c b/src/main/sensors/battery.c index e8b585f44c..7419eded90 100644 --- a/src/main/sensors/battery.c +++ b/src/main/sensors/battery.c @@ -17,12 +17,10 @@ #include "stdbool.h" #include "stdint.h" -#include #include "platform.h" #include "common/maths.h" -#include "common/filter.h" #include "drivers/adc.h" #include "drivers/system.h" @@ -35,6 +33,7 @@ #include "rx/rx.h" #include "io/rc_controls.h" +#include "flight/lowpass.h" #include "io/beeper.h" #define VBATT_PRESENT_THRESHOLD_MV 10 @@ -55,6 +54,7 @@ int32_t mAhDrawn = 0; // milliampere hours drawn from the battery batteryConfig_t *batteryConfig; static batteryState_e batteryState; +static lowpass_t lowpassFilter; uint16_t batteryAdcToVoltage(uint16_t src) { @@ -66,18 +66,12 @@ uint16_t batteryAdcToVoltage(uint16_t src) static void updateBatteryVoltage(void) { uint16_t vbatSample; - biquad_t vbatFilterState; - static bool vbatFilterIsSet; - - if (!vbatFilterIsSet) { - BiQuadNewLpf(0.5f, &vbatFilterState, 20000); - vbatFilterIsSet = true; - } + uint16_t vbatFiltered; // store the battery voltage with some other recent battery voltage readings vbatSample = vbatLatestADC = adcGetChannel(ADC_BATTERY); - vbatSample = lrintf(applyBiQuadFilter((float) vbatSample, &vbatFilterState)); - vbat = batteryAdcToVoltage(vbatSample); + vbatFiltered = (uint16_t)lowpassFixed(&lowpassFilter, vbatSample, VBATT_LPF_FREQ); + vbat = batteryAdcToVoltage(vbatFiltered); } #define VBATTERY_STABLE_DELAY 40