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micropython/ports/rp2/machine_pwm.c

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/*
* This file is part of the MicroPython project, http://micropython.org/
*
* The MIT License (MIT)
*
* Copyright (c) 2020-2021 Damien P. George
*
* 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 "py/runtime.h"
#include "py/mphal.h"
#include "modmachine.h"
#include "hardware/clocks.h"
#include "hardware/pwm.h"
/******************************************************************************/
// MicroPython bindings for machine.PWM
typedef struct _machine_pwm_obj_t {
mp_obj_base_t base;
uint8_t slice;
uint8_t channel;
uint8_t duty_type;
mp_int_t duty;
} machine_pwm_obj_t;
enum {
DUTY_NOT_SET = 0,
DUTY_U16,
DUTY_NS
};
STATIC machine_pwm_obj_t machine_pwm_obj[] = {
{{&machine_pwm_type}, 0, PWM_CHAN_A, DUTY_NOT_SET, 0},
{{&machine_pwm_type}, 0, PWM_CHAN_B, DUTY_NOT_SET, 0},
{{&machine_pwm_type}, 1, PWM_CHAN_A, DUTY_NOT_SET, 0},
{{&machine_pwm_type}, 1, PWM_CHAN_B, DUTY_NOT_SET, 0},
{{&machine_pwm_type}, 2, PWM_CHAN_A, DUTY_NOT_SET, 0},
{{&machine_pwm_type}, 2, PWM_CHAN_B, DUTY_NOT_SET, 0},
{{&machine_pwm_type}, 3, PWM_CHAN_A, DUTY_NOT_SET, 0},
{{&machine_pwm_type}, 3, PWM_CHAN_B, DUTY_NOT_SET, 0},
{{&machine_pwm_type}, 4, PWM_CHAN_A, DUTY_NOT_SET, 0},
{{&machine_pwm_type}, 4, PWM_CHAN_B, DUTY_NOT_SET, 0},
{{&machine_pwm_type}, 5, PWM_CHAN_A, DUTY_NOT_SET, 0},
{{&machine_pwm_type}, 5, PWM_CHAN_B, DUTY_NOT_SET, 0},
{{&machine_pwm_type}, 6, PWM_CHAN_A, DUTY_NOT_SET, 0},
{{&machine_pwm_type}, 6, PWM_CHAN_B, DUTY_NOT_SET, 0},
{{&machine_pwm_type}, 7, PWM_CHAN_A, DUTY_NOT_SET, 0},
{{&machine_pwm_type}, 7, PWM_CHAN_B, DUTY_NOT_SET, 0},
};
STATIC void mp_machine_pwm_duty_set_u16(machine_pwm_obj_t *self, mp_int_t duty_u16);
STATIC void mp_machine_pwm_duty_set_ns(machine_pwm_obj_t *self, mp_int_t duty_ns);
STATIC void mp_machine_pwm_print(const mp_print_t *print, mp_obj_t self_in, mp_print_kind_t kind) {
machine_pwm_obj_t *self = MP_OBJ_TO_PTR(self_in);
mp_printf(print, "<PWM slice=%u channel=%u>", self->slice, self->channel);
}
// PWM(pin)
STATIC mp_obj_t mp_machine_pwm_make_new(const mp_obj_type_t *type, size_t n_args, size_t n_kw, const mp_obj_t *all_args) {
// Check number of arguments
mp_arg_check_num(n_args, n_kw, 1, 1, false);
// Get GPIO to connect to PWM.
uint32_t gpio = mp_hal_get_pin_obj(all_args[0]);
// Get static peripheral object.
uint slice = pwm_gpio_to_slice_num(gpio);
uint8_t channel = pwm_gpio_to_channel(gpio);
machine_pwm_obj_t *self = &machine_pwm_obj[slice * 2 + channel];
self->duty_type = DUTY_NOT_SET;
// Select PWM function for given GPIO.
gpio_set_function(gpio, GPIO_FUNC_PWM);
return MP_OBJ_FROM_PTR(self);
}
STATIC void mp_machine_pwm_deinit(machine_pwm_obj_t *self) {
self->duty_type = DUTY_NOT_SET;
pwm_set_enabled(self->slice, false);
}
// Returns: floor((16*F + offset) / div16)
// Avoids overflow in the numerator that would occur if
// 16*F + offset > 2**32
// F + offset/16 > 2**28 = 268435456 (approximately, due to flooring)
uint32_t get_slice_hz(uint32_t offset, uint32_t div16) {
uint32_t source_hz = clock_get_hz(clk_sys);
if (source_hz + offset / 16 > 268000000) {
return (16 * (uint64_t)source_hz + offset) / div16;
} else {
return (16 * source_hz + offset) / div16;
}
}
// Returns 16*F / denom, rounded.
uint32_t get_slice_hz_round(uint32_t div16) {
return get_slice_hz(div16 / 2, div16);
}
// Returns ceil(16*F / denom).
uint32_t get_slice_hz_ceil(uint32_t div16) {
return get_slice_hz(div16 - 1, div16);
}
STATIC mp_obj_t mp_machine_pwm_freq_get(machine_pwm_obj_t *self) {
uint32_t div16 = pwm_hw->slice[self->slice].div;
uint32_t top = pwm_hw->slice[self->slice].top;
uint32_t pwm_freq = get_slice_hz_round(div16 * (top + 1));
return MP_OBJ_NEW_SMALL_INT(pwm_freq);
}
STATIC void mp_machine_pwm_freq_set(machine_pwm_obj_t *self, mp_int_t freq) {
// Set the frequency, making "top" as large as possible for maximum resolution.
// Maximum "top" is set at 65534 to be able to achieve 100% duty with 65535.
#define TOP_MAX 65534
uint32_t source_hz = clock_get_hz(clk_sys);
uint32_t div16;
uint32_t top;
if ((source_hz + freq / 2) / freq < TOP_MAX) {
// If possible (based on the formula for TOP below), use a DIV of 1.
// This also prevents overflow in the DIV calculation.
div16 = 16;
// Same as get_slice_hz_round() below but canceling the 16s
// to avoid overflow for high freq.
top = (source_hz + freq / 2) / freq - 1;
} else {
// Otherwise, choose the smallest possible DIV for maximum
// duty cycle resolution.
// Constraint: 16*F/(div16*freq) < TOP_MAX
// So:
div16 = get_slice_hz_ceil(TOP_MAX * freq);
// Set TOP as accurately as possible using rounding.
top = get_slice_hz_round(div16 * freq) - 1;
}
if (div16 < 16) {
mp_raise_ValueError(MP_ERROR_TEXT("freq too large"));
} else if (div16 >= 256 * 16) {
mp_raise_ValueError(MP_ERROR_TEXT("freq too small"));
}
pwm_hw->slice[self->slice].div = div16;
pwm_hw->slice[self->slice].top = top;
if (self->duty_type == DUTY_U16) {
mp_machine_pwm_duty_set_u16(self, self->duty);
} else if (self->duty_type == DUTY_NS) {
mp_machine_pwm_duty_set_ns(self, self->duty);
}
}
STATIC mp_obj_t mp_machine_pwm_duty_get_u16(machine_pwm_obj_t *self) {
uint32_t top = pwm_hw->slice[self->slice].top;
uint32_t cc = pwm_hw->slice[self->slice].cc;
cc = (cc >> (self->channel ? PWM_CH0_CC_B_LSB : PWM_CH0_CC_A_LSB)) & 0xffff;
// Use rounding (instead of flooring) here to give as accurate an
// estimate as possible.
return MP_OBJ_NEW_SMALL_INT((cc * 65535 + (top + 1) / 2) / (top + 1));
}
STATIC void mp_machine_pwm_duty_set_u16(machine_pwm_obj_t *self, mp_int_t duty_u16) {
uint32_t top = pwm_hw->slice[self->slice].top;
// Use rounding here to set it as accurately as possible.
uint32_t cc = (duty_u16 * (top + 1) + 65535 / 2) / 65535;
pwm_set_chan_level(self->slice, self->channel, cc);
pwm_set_enabled(self->slice, true);
self->duty = duty_u16;
self->duty_type = DUTY_U16;
}
STATIC mp_obj_t mp_machine_pwm_duty_get_ns(machine_pwm_obj_t *self) {
uint32_t slice_hz = get_slice_hz_round(pwm_hw->slice[self->slice].div);
uint32_t cc = pwm_hw->slice[self->slice].cc;
cc = (cc >> (self->channel ? PWM_CH0_CC_B_LSB : PWM_CH0_CC_A_LSB)) & 0xffff;
return MP_OBJ_NEW_SMALL_INT(((uint64_t)cc * 1000000000ULL + slice_hz / 2) / slice_hz);
}
STATIC void mp_machine_pwm_duty_set_ns(machine_pwm_obj_t *self, mp_int_t duty_ns) {
uint32_t slice_hz = get_slice_hz_round(pwm_hw->slice[self->slice].div);
uint32_t cc = ((uint64_t)duty_ns * slice_hz + 500000000ULL) / 1000000000ULL;
if (cc > 65535) {
mp_raise_ValueError(MP_ERROR_TEXT("duty larger than period"));
}
pwm_set_chan_level(self->slice, self->channel, cc);
pwm_set_enabled(self->slice, true);
self->duty = duty_ns;
self->duty_type = DUTY_NS;
}
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