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

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/*
* This file is part of the MicroPython project, http://micropython.org/
*
* The MIT License (MIT)
*
* Copyright (c) 2017 Scott Shawcroft 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/PulseIn.h"
#include <stdint.h>
#include <string.h>
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#include "nrf/timers.h"
#include "py/mpconfig.h"
#include "py/gc.h"
#include "py/runtime.h"
#include "shared-bindings/microcontroller/__init__.h"
#include "shared-bindings/pulseio/PulseIn.h"
#include "nrfx_gpiote.h"
// obj array to map pin -> self since nrfx hide the mapping
static pulseio_pulsein_obj_t* _objs[GPIOTE_CH_NUM];
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// A single timer is shared amongst all PulseIn objects as a common high speed clock reference.
static uint8_t refcount = 0;
static nrfx_timer_t *timer = NULL;
static uint32_t overflow_count = 0;
static void timer_overflow_event_handler(nrf_timer_event_t event_type, void *p_context) {
if (event_type != NRF_TIMER_EVENT_COMPARE0) {
// Other event.
return;
}
overflow_count++;
}
// return index of the object in array
static int _find_pulsein_obj(pulseio_pulsein_obj_t* obj) {
for(size_t i = 0; i < NRFX_ARRAY_SIZE(_objs); i++ ) {
if ( _objs[i] == obj) {
return i;
}
}
return -1;
}
static void _pulsein_handler(nrfx_gpiote_pin_t pin, nrf_gpiote_polarity_t action) {
// Grab the current time first.
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uint32_t current_overflow = overflow_count;
uint32_t current_count = nrfx_timer_capture(timer, 1);
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pulseio_pulsein_obj_t* self = NULL;
for(size_t i = 0; i < NRFX_ARRAY_SIZE(_objs); i++ ) {
if ( _objs[i] && _objs[i]->pin == pin ) {
self = _objs[i];
break;
}
}
if ( !self ) return;
if (self->first_edge) {
// first pulse is opposite state from idle
bool state = nrf_gpio_pin_read(self->pin);
if ( self->idle_state != state ) {
self->first_edge = false;
}
}else {
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// Wrapped around a number of times.
uint32_t total_diff = 0xffff;
// Wrapped around once so
if (self->last_overflow == current_overflow - 1) {
total_diff = current_count + (0xffffffff - self->last_count);
} else if (self->last_overflow == current_overflow) {
total_diff = current_count - self->last_count;
}
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// Cap duration at 16 bits.
uint16_t duration = 0xffff;
if (total_diff < duration) {
duration = total_diff;
}
uint16_t i = (self->start + self->len) % self->maxlen;
self->buffer[i] = duration;
if (self->len < self->maxlen) {
self->len++;
} else {
self->start++;
}
}
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self->last_overflow = current_overflow;
self->last_count = current_count;
}
void pulsein_reset(void) {
if ( nrfx_gpiote_is_init() ) {
nrfx_gpiote_uninit();
}
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nrfx_gpiote_init(NRFX_GPIOTE_CONFIG_IRQ_PRIORITY);
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if (timer != NULL) {
nrf_peripherals_free_timer(timer);
}
refcount = 0;
memset(_objs, 0, sizeof(_objs));
}
void common_hal_pulseio_pulsein_construct(pulseio_pulsein_obj_t* self, const mcu_pin_obj_t* pin, uint16_t maxlen, bool idle_state) {
int idx = _find_pulsein_obj(NULL);
if ( idx < 0 ) {
mp_raise_NotImplementedError(NULL);
}
_objs[idx] = self;
self->buffer = (uint16_t *) m_malloc(maxlen * sizeof(uint16_t), false);
if (self->buffer == NULL) {
mp_raise_msg_varg(&mp_type_MemoryError, translate("Failed to allocate RX buffer of %d bytes"), maxlen * sizeof(uint16_t));
}
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if (refcount == 0) {
timer = nrf_peripherals_allocate_timer();
if (timer == NULL) {
mp_raise_RuntimeError(translate("All timers in use"));
}
overflow_count = 0;
nrfx_timer_config_t timer_config = {
// PulseIn 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,
};
nrfx_timer_init(timer, &timer_config, &timer_overflow_event_handler);
// Interrupt on overflow so we can track when it rolls over.
nrfx_timer_compare(timer, 0, 0, true);
}
refcount++;
self->pin = pin->number;
self->maxlen = maxlen;
self->idle_state = idle_state;
self->start = 0;
self->len = 0;
self->first_edge = true;
self->paused = false;
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self->last_overflow = 0;
self->last_count = 0;
claim_pin(pin);
nrfx_gpiote_in_config_t cfg = {
.sense = NRF_GPIOTE_POLARITY_TOGGLE,
.pull = NRF_GPIO_PIN_NOPULL, // idle_state ? NRF_GPIO_PIN_PULLDOWN : NRF_GPIO_PIN_PULLUP,
.is_watcher = false, // nrf_gpio_cfg_watcher vs nrf_gpio_cfg_input
.hi_accuracy = true,
.skip_gpio_setup = false
};
nrfx_gpiote_in_init(self->pin, &cfg, _pulsein_handler);
nrfx_gpiote_in_event_enable(self->pin, true);
}
bool common_hal_pulseio_pulsein_deinited(pulseio_pulsein_obj_t* self) {
return self->pin == NO_PIN;
}
void common_hal_pulseio_pulsein_deinit(pulseio_pulsein_obj_t* self) {
if (common_hal_pulseio_pulsein_deinited(self)) {
return;
}
nrfx_gpiote_in_event_disable(self->pin);
nrfx_gpiote_in_uninit(self->pin);
// mark local array as invalid
int idx = _find_pulsein_obj(self);
if ( idx < 0 ) {
mp_raise_NotImplementedError(NULL);
}
_objs[idx] = NULL;
reset_pin_number(self->pin);
self->pin = NO_PIN;
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refcount--;
if (refcount == 0) {
nrf_peripherals_free_timer(timer);
}
}
void common_hal_pulseio_pulsein_pause(pulseio_pulsein_obj_t* self) {
nrfx_gpiote_in_event_disable(self->pin);
self->paused = true;
}
void common_hal_pulseio_pulsein_resume(pulseio_pulsein_obj_t* self, uint16_t trigger_duration) {
// Make sure we're paused.
if ( !self->paused ) {
common_hal_pulseio_pulsein_pause(self);
}
// Send the trigger pulse.
if (trigger_duration > 0) {
nrfx_gpiote_in_uninit(self->pin);
nrf_gpio_cfg_output(self->pin);
nrf_gpio_pin_write(self->pin, !self->idle_state);
common_hal_mcu_delay_us((uint32_t)trigger_duration);
nrf_gpio_pin_write(self->pin, self->idle_state);
nrfx_gpiote_in_config_t cfg = {
.sense = NRF_GPIOTE_POLARITY_TOGGLE,
.pull = NRF_GPIO_PIN_NOPULL, // idle_state ? NRF_GPIO_PIN_PULLDOWN : NRF_GPIO_PIN_PULLUP,
.is_watcher = false, // nrf_gpio_cfg_watcher vs nrf_gpio_cfg_input
.hi_accuracy = true,
.skip_gpio_setup = false
};
nrfx_gpiote_in_init(self->pin, &cfg, _pulsein_handler);
}
self->first_edge = true;
self->paused = false;
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self->last_overflow = 0;
self->last_count = 0;
nrfx_gpiote_in_event_enable(self->pin, true);
}
void common_hal_pulseio_pulsein_clear(pulseio_pulsein_obj_t* self) {
if ( !self->paused ) {
nrfx_gpiote_in_event_disable(self->pin);
}
self->start = 0;
self->len = 0;
if ( !self->paused ) {
nrfx_gpiote_in_event_enable(self->pin, true);
}
}
uint16_t common_hal_pulseio_pulsein_get_item(pulseio_pulsein_obj_t* self, int16_t index) {
if ( !self->paused ) {
nrfx_gpiote_in_event_disable(self->pin);
}
if (index < 0) {
index += self->len;
}
if (index < 0 || index >= self->len) {
if ( !self->paused ) {
nrfx_gpiote_in_event_enable(self->pin, true);
}
mp_raise_IndexError(translate("index out of range"));
}
uint16_t value = self->buffer[(self->start + index) % self->maxlen];
if ( !self->paused ) {
nrfx_gpiote_in_event_enable(self->pin, true);
}
return value;
}
uint16_t common_hal_pulseio_pulsein_popleft(pulseio_pulsein_obj_t* self) {
if (self->len == 0) {
mp_raise_IndexError(translate("pop from an empty PulseIn"));
}
if ( !self->paused ) {
nrfx_gpiote_in_event_disable(self->pin);
}
uint16_t value = self->buffer[self->start];
self->start = (self->start + 1) % self->maxlen;
self->len--;
if ( !self->paused ) {
nrfx_gpiote_in_event_enable(self->pin, true);
}
return value;
}
uint16_t common_hal_pulseio_pulsein_get_maxlen(pulseio_pulsein_obj_t* self) {
return self->maxlen;
}
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bool common_hal_pulseio_pulsein_get_paused(pulseio_pulsein_obj_t* self) {
return self->paused;
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}
uint16_t common_hal_pulseio_pulsein_get_len(pulseio_pulsein_obj_t* self) {
return self->len;
}