diff options
Diffstat (limited to 'src/modules/systemlib/pwm_limit/pwm_limit.c')
-rw-r--r-- | src/modules/systemlib/pwm_limit/pwm_limit.c | 116 |
1 files changed, 116 insertions, 0 deletions
diff --git a/src/modules/systemlib/pwm_limit/pwm_limit.c b/src/modules/systemlib/pwm_limit/pwm_limit.c new file mode 100644 index 000000000..675247578 --- /dev/null +++ b/src/modules/systemlib/pwm_limit/pwm_limit.c @@ -0,0 +1,116 @@ +/**************************************************************************** + * + * Copyright (C) 2013 PX4 Development Team. All rights reserved. + * Author: Julian Oes <joes@student.ethz.ch> + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in + * the documentation and/or other materials provided with the + * distribution. + * 3. Neither the name PX4 nor the names of its contributors may be + * used to endorse or promote products derived from this software + * without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS + * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT + * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS + * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE + * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, + * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, + * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS + * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED + * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT + * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN + * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE + * POSSIBILITY OF SUCH DAMAGE. + * + ****************************************************************************/ + +/** + * @file pwm_limit.c + * + * Lib to limit PWM output + * + * @author Julian Oes <joes@student.ethz.ch> + */ + +#include "pwm_limit.h" +#include <math.h> +#include <stdbool.h> +#include <drivers/drv_hrt.h> + +__EXPORT pwm_limit_init(pwm_limit_t *limit) +{ + limit->nchannels = 0; + limit->state = LIMIT_STATE_OFF; + limit->time_armed = 0; + return; +} + +__EXPORT void pwm_limit_calc(const bool armed, const uint16_t *disarmed_pwm, const uint16_t *min_pwm, const uint16_t *max_pwm, const float *output_requested, uint16_t *effective_pwm, pwm_limit_t *limit) +{ + /* first evaluate state changes */ + switch (limit->state) { + case LIMIT_STATE_OFF: + if (armed) + limit->state = LIMIT_STATE_RAMP; + limit->time_armed = hrt_absolute_time(); + break; + case LIMIT_STATE_INIT: + if (!armed) + limit->state = LIMIT_STATE_OFF; + else if (hrt_absolute_time() - limit->time_armed >= INIT_TIME_US) + limit->state = LIMIT_STATE_RAMP; + break; + case LIMIT_STATE_RAMP: + if (!armed) + limit->state = LIMIT_STATE_OFF; + else if (hrt_absolute_time() - limit->time_armed >= INIT_TIME_US + RAMP_TIME_US) + limit->state = LIMIT_STATE_ON; + break; + case LIMIT_STATE_ON: + if (!armed) + limit->state = LIMIT_STATE_OFF; + break; + default: + break; + } + + unsigned progress; + uint16_t temp_pwm; + + /* then set effective_pwm based on state */ + switch (limit->state) { + case LIMIT_STATE_OFF: + case LIMIT_STATE_INIT: + for (unsigned i=0; i<limit->nchannels; i++) { + effective_pwm[i] = disarmed_pwm[i]; + } + break; + case LIMIT_STATE_RAMP: + + progress = (hrt_absolute_time() - INIT_TIME_US - limit->time_armed)*10000 / RAMP_TIME_US; + for (unsigned i=0; i<limit->nchannels; i++) { + + temp_pwm = output_requested[i] * (max_pwm[i] - min_pwm[i])/2 + (max_pwm[i] + min_pwm[i])/2; + /* already follow user/controller input if higher than min_pwm */ + effective_pwm[i] = (disarmed_pwm[i]*(10000-progress) + (temp_pwm > min_pwm[i] ? temp_pwm : min_pwm[i])*progress)/10000; + + } + break; + case LIMIT_STATE_ON: + for (unsigned i=0; i<limit->nchannels; i++) { + effective_pwm[i] = output_requested[i] * (max_pwm[i] - min_pwm[i])/2 + (max_pwm[i] + min_pwm[i])/2; + } + break; + default: + break; + } + return; +} |