circuitpython/ports/nrf/common-hal/pulseio/PulseOut.c

171 lines
5.1 KiB
C

/*
* This file is part of the MicroPython project, http://micropython.org/
*
* The MIT License (MIT)
*
* Copyright (c) 2018 Dan Halbert for Adafruit Industries
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
#include "common-hal/pulseio/PulseOut.h"
#include <stdint.h>
#include "py/mpconfig.h"
#include "nrf/pins.h"
#include "nrf/timers.h"
#include "py/gc.h"
#include "py/runtime.h"
#include "shared-bindings/pulseio/PulseOut.h"
#include "shared-bindings/pwmio/PWMOut.h"
// A single timer is shared amongst all PulseOut objects under the assumption that
// the code is single threaded.
static uint8_t refcount = 0;
static nrfx_timer_t *timer = NULL;
static uint16_t *pulse_array = NULL;
static volatile uint16_t pulse_array_index = 0;
static uint16_t pulse_array_length;
static void turn_on(pulseio_pulseout_obj_t *pulseout) {
pulseout->pwmout.pwm->PSEL.OUT[0] = pulseout->pwmout.pin->number;
}
static void turn_off(pulseio_pulseout_obj_t *pulseout) {
// Disconnect pin from PWM.
pulseout->pwmout.pwm->PSEL.OUT[0] = 0xffffffff;
// Make sure pin is low.
nrf_gpio_pin_clear(pulseout->pwmout.pin->number);
}
static void start_timer(void) {
nrfx_timer_clear(timer);
// true enables interrupt.
nrfx_timer_compare(timer, NRF_TIMER_CC_CHANNEL0, pulse_array[pulse_array_index], true);
nrfx_timer_resume(timer);
}
static void pulseout_event_handler(nrf_timer_event_t event_type, void *p_context) {
pulseio_pulseout_obj_t *pulseout = (pulseio_pulseout_obj_t *)p_context;
if (event_type != NRF_TIMER_EVENT_COMPARE0) {
// Spurious event.
return;
}
nrfx_timer_pause(timer);
pulse_array_index++;
// Ignore a zero-length pulse
while (pulse_array_index < pulse_array_length &&
pulse_array[pulse_array_index] == 0) {
pulse_array_index++;
}
// No more pulses. Turn off output and don't restart.
if (pulse_array_index >= pulse_array_length) {
turn_off(pulseout);
return;
}
// Alternate on and off, starting with on.
if (pulse_array_index % 2 == 0) {
turn_on(pulseout);
} else {
turn_off(pulseout);
}
// Count up to the next given value.
start_timer();
}
void pulseout_reset() {
if (timer != NULL) {
nrf_peripherals_free_timer(timer);
}
refcount = 0;
}
void common_hal_pulseio_pulseout_construct(pulseio_pulseout_obj_t *self,
const mcu_pin_obj_t *pin,
uint32_t frequency,
uint16_t duty_cycle) {
pwmout_result_t result = common_hal_pwmio_pwmout_construct(
&self->pwmout, pin, duty_cycle, frequency, false);
// This will raise an exception and not return if needed.
common_hal_pwmio_pwmout_raise_error(result);
if (refcount == 0) {
timer = nrf_peripherals_allocate_timer_or_throw();
}
refcount++;
nrfx_timer_config_t timer_config = {
// PulseOut durations are in microseconds, so this is convenient.
.frequency = NRF_TIMER_FREQ_1MHz,
.mode = NRF_TIMER_MODE_TIMER,
.bit_width = NRF_TIMER_BIT_WIDTH_32,
.interrupt_priority = NRFX_TIMER_DEFAULT_CONFIG_IRQ_PRIORITY,
.p_context = self,
};
nrfx_timer_init(timer, &timer_config, &pulseout_event_handler);
turn_off(self);
}
bool common_hal_pulseio_pulseout_deinited(pulseio_pulseout_obj_t *self) {
return common_hal_pwmio_pwmout_deinited(&self->pwmout);
}
void common_hal_pulseio_pulseout_deinit(pulseio_pulseout_obj_t *self) {
if (common_hal_pulseio_pulseout_deinited(self)) {
return;
}
turn_on(self);
common_hal_pwmio_pwmout_deinit(&self->pwmout);
refcount--;
if (refcount == 0) {
nrf_peripherals_free_timer(timer);
}
}
void common_hal_pulseio_pulseout_send(pulseio_pulseout_obj_t *self, uint16_t *pulses, uint16_t length) {
pulse_array = pulses;
pulse_array_index = 0;
pulse_array_length = length;
nrfx_timer_enable(timer);
turn_on(self);
// Count up to the next given value.
start_timer();
while (pulse_array_index < length) {
// Do other things while we wait. The interrupts will handle sending the
// signal.
RUN_BACKGROUND_TASKS;
}
nrfx_timer_disable(timer);
}