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

299 lines
9.7 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 <stdint.h>
#include "nrf.h"
#include "py/runtime.h"
#include "common-hal/pulseio/PWMOut.h"
#include "shared-bindings/pulseio/PWMOut.h"
#include "supervisor/shared/translate.h"
#include "nrf_gpio.h"
#define PWM_MAX_FREQ (16000000)
STATIC NRF_PWM_Type* pwms[] = {
#if NRFX_CHECK(NRFX_PWM0_ENABLED)
NRF_PWM0,
#endif
#if NRFX_CHECK(NRFX_PWM1_ENABLED)
NRF_PWM1,
#endif
#if NRFX_CHECK(NRFX_PWM2_ENABLED)
NRF_PWM2,
#endif
#if NRFX_CHECK(NRFX_PWM3_ENABLED)
NRF_PWM3,
#endif
};
#define CHANNELS_PER_PWM 4
STATIC uint16_t pwm_seq[MP_ARRAY_SIZE(pwms)][CHANNELS_PER_PWM];
static uint8_t never_reset_pwm[MP_ARRAY_SIZE(pwms)];
STATIC int pwm_idx(NRF_PWM_Type *pwm) {
for(size_t i=0; i < MP_ARRAY_SIZE(pwms); i++)
if(pwms[i] == pwm) return i;
return -1;
}
void common_hal_pulseio_pwmout_never_reset(pulseio_pwmout_obj_t *self) {
for(size_t i=0; i < MP_ARRAY_SIZE(pwms); i++) {
NRF_PWM_Type* pwm = pwms[i];
if (pwm == self->pwm) {
never_reset_pwm[i] += 1;
}
}
never_reset_pin_number(self->pin_number);
}
void common_hal_pulseio_pwmout_reset_ok(pulseio_pwmout_obj_t *self) {
for(size_t i=0; i < MP_ARRAY_SIZE(pwms); i++) {
NRF_PWM_Type* pwm = pwms[i];
if (pwm == self->pwm) {
never_reset_pwm[i] -= 1;
}
}
}
void reset_single_pwmout(uint8_t i) {
NRF_PWM_Type* pwm = pwms[i];
pwm->ENABLE = 0;
pwm->MODE = PWM_MODE_UPDOWN_Up;
pwm->DECODER = PWM_DECODER_LOAD_Individual;
pwm->LOOP = 0;
pwm->PRESCALER = PWM_PRESCALER_PRESCALER_DIV_1; // default is 500 hz
pwm->COUNTERTOP = (PWM_MAX_FREQ/500); // default is 500 hz
pwm->SEQ[0].PTR = (uint32_t) pwm_seq[i];
pwm->SEQ[0].CNT = CHANNELS_PER_PWM; // default mode is Individual --> count must be 4
pwm->SEQ[0].REFRESH = 0;
pwm->SEQ[0].ENDDELAY = 0;
pwm->SEQ[1].PTR = 0;
pwm->SEQ[1].CNT = 0;
pwm->SEQ[1].REFRESH = 0;
pwm->SEQ[1].ENDDELAY = 0;
for(int ch =0; ch < CHANNELS_PER_PWM; ch++) {
pwm_seq[i][ch] = (1 << 15); // polarity = 0
}
}
void pwmout_reset(void) {
for(size_t i=0; i < MP_ARRAY_SIZE(pwms); i++) {
if (never_reset_pwm[i] > 0) {
continue;
}
reset_single_pwmout(i);
}
}
// Find the smallest prescaler value that will allow the divisor to be in range.
// This allows the most accuracy.
bool convert_frequency(uint32_t frequency, uint16_t *countertop, nrf_pwm_clk_t *base_clock) {
uint32_t divisor = 1;
// Use a 32-bit number so we don't overflow the uint16_t;
uint32_t tentative_countertop;
for (*base_clock = PWM_PRESCALER_PRESCALER_DIV_1;
*base_clock <= PWM_PRESCALER_PRESCALER_DIV_128;
(*base_clock)++) {
tentative_countertop = PWM_MAX_FREQ / divisor / frequency;
// COUNTERTOP must be 3..32767, according to datasheet, but 3 doesn't work. 4 does.
if (tentative_countertop <= 32767 && tentative_countertop >= 4) {
// In range, OK to return.
*countertop = tentative_countertop;
return true;
}
divisor *= 2;
}
return false;
}
NRF_PWM_Type *pwmout_allocate(uint16_t countertop, nrf_pwm_clk_t base_clock,
bool variable_frequency, int8_t *channel_out, bool *pwm_already_in_use_out) {
for (size_t pwm_index = 0; pwm_index < MP_ARRAY_SIZE(pwms); pwm_index++) {
NRF_PWM_Type *pwm = pwms[pwm_index];
bool pwm_already_in_use = pwm->ENABLE & SPIM_ENABLE_ENABLE_Msk;
if (pwm_already_in_use) {
if (variable_frequency) {
// Variable frequency requires exclusive use of a PWM, so try the next one.
continue;
}
// PWM is in use, but see if it's set to the same frequency we need. If so,
// look for a free channel.
if (pwm->COUNTERTOP == countertop && pwm->PRESCALER == base_clock) {
for (size_t chan = 0; chan < CHANNELS_PER_PWM; chan++) {
if (pwm->PSEL.OUT[chan] == 0xFFFFFFFF) {
// Channel is free.
if(channel_out)
*channel_out = chan;
if(pwm_already_in_use_out)
*pwm_already_in_use_out = pwm_already_in_use;
return pwm;
}
}
}
} else {
// PWM not yet in use, so we can start to use it. Use channel 0.
if(channel_out)
*channel_out = 0;
if(pwm_already_in_use_out)
*pwm_already_in_use_out = pwm_already_in_use;
return pwm;
}
}
return NULL;
}
void pwmout_free_channel(NRF_PWM_Type *pwm, int8_t channel) {
// Disconnect pin from channel.
pwm->PSEL.OUT[channel] = 0xFFFFFFFF;
for(int i=0; i < CHANNELS_PER_PWM; i++) {
if (pwm->PSEL.OUT[i] != 0xFFFFFFFF) {
// Some channel is still being used, so don't disable.
return;
}
}
nrf_pwm_disable(pwm);
}
pwmout_result_t common_hal_pulseio_pwmout_construct(pulseio_pwmout_obj_t* self,
const mcu_pin_obj_t* pin,
uint16_t duty,
uint32_t frequency,
bool variable_frequency) {
// We don't use the nrfx driver here because we want to dynamically allocate channels
// as needed in an already-enabled PWM.
uint16_t countertop;
nrf_pwm_clk_t base_clock;
if (frequency == 0 || !convert_frequency(frequency, &countertop, &base_clock)) {
return PWMOUT_INVALID_FREQUENCY;
}
int8_t channel;
bool pwm_already_in_use;
self->pwm = pwmout_allocate(countertop, base_clock, variable_frequency,
&channel, &pwm_already_in_use);
if (self->pwm == NULL) {
return PWMOUT_ALL_TIMERS_IN_USE;
}
self->channel = channel;
self->pin_number = pin->number;
claim_pin(pin);
self->frequency = frequency;
self->variable_frequency = variable_frequency;
// Note this is standard, not strong drive.
nrf_gpio_cfg_output(self->pin_number);
// disable before mapping pin channel
nrf_pwm_disable(self->pwm);
if (!pwm_already_in_use) {
reset_single_pwmout(pwm_idx(self->pwm));
nrf_pwm_configure(self->pwm, base_clock, NRF_PWM_MODE_UP, countertop);
}
// Connect channel to pin, without disturbing other channels.
self->pwm->PSEL.OUT[self->channel] = pin->number;
nrf_pwm_enable(self->pwm);
common_hal_pulseio_pwmout_set_duty_cycle(self, duty);
return PWMOUT_OK;
}
bool common_hal_pulseio_pwmout_deinited(pulseio_pwmout_obj_t* self) {
return self->pwm == NULL;
}
void common_hal_pulseio_pwmout_deinit(pulseio_pwmout_obj_t* self) {
if (common_hal_pulseio_pwmout_deinited(self)) {
return;
}
nrf_gpio_cfg_default(self->pin_number);
NRF_PWM_Type* pwm = self->pwm;
self->pwm = NULL;
pwmout_free_channel(pwm, self->channel);
reset_pin_number(self->pin_number);
self->pin_number = NO_PIN;
}
void common_hal_pulseio_pwmout_set_duty_cycle(pulseio_pwmout_obj_t* self, uint16_t duty_cycle) {
self->duty_cycle = duty_cycle;
uint16_t* p_value = ((uint16_t*)self->pwm->SEQ[0].PTR) + self->channel;
*p_value = ((duty_cycle * self->pwm->COUNTERTOP) / 0xFFFF) | (1 << 15);
self->pwm->TASKS_SEQSTART[0] = 1;
}
uint16_t common_hal_pulseio_pwmout_get_duty_cycle(pulseio_pwmout_obj_t* self) {
return self->duty_cycle;
}
void common_hal_pulseio_pwmout_set_frequency(pulseio_pwmout_obj_t* self, uint32_t frequency) {
// COUNTERTOP is 3..32767, so highest available frequency is PWM_MAX_FREQ / 3.
uint16_t countertop;
nrf_pwm_clk_t base_clock;
if (frequency == 0 || !convert_frequency(frequency, &countertop, &base_clock)) {
mp_raise_ValueError(translate("Invalid PWM frequency"));
}
self->frequency = frequency;
nrf_pwm_configure(self->pwm, base_clock, NRF_PWM_MODE_UP, countertop);
// Set the duty cycle again, because it depends on COUNTERTOP, which probably changed.
// Setting the duty cycle will also do a SEQSTART.
common_hal_pulseio_pwmout_set_duty_cycle(self, self->duty_cycle);
}
uint32_t common_hal_pulseio_pwmout_get_frequency(pulseio_pwmout_obj_t* self) {
return self->frequency;
}
bool common_hal_pulseio_pwmout_get_variable_frequency(pulseio_pwmout_obj_t* self) {
return self->variable_frequency;
}