74 lines
2.8 KiB
C++
74 lines
2.8 KiB
C++
#include "Pwm.h"
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#include "Config.h"
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#include "Core.h"
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#include <hal/ledc_ll.h>
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namespace {
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constexpr ledc_mode_t PWM_SPEED_MODE = LEDC_LOW_SPEED_MODE;
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constexpr ledc_timer_t PWM_TIMER = LEDC_TIMER_0;
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void setIntegerDivider(uint16_t divider) {
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ledc_dev_t *hardware = LEDC_LL_GET_HW();
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ledc_ll_timer_pause(hardware, PWM_SPEED_MODE, PWM_TIMER);
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ledc_ll_set_clock_divider(hardware, PWM_SPEED_MODE, PWM_TIMER,
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static_cast<uint32_t>(divider) << LEDC_LL_FRACTIONAL_BITS);
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ledc_ll_timer_rst(hardware, PWM_SPEED_MODE, PWM_TIMER);
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ledc_ll_ls_timer_update(hardware, PWM_SPEED_MODE, PWM_TIMER);
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ledc_ll_timer_resume(hardware, PWM_SPEED_MODE, PWM_TIMER);
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}
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bool integerDividerIsSet(uint16_t expected) {
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uint32_t rawDivider = 0;
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ledc_ll_get_clock_divider(LEDC_LL_GET_HW(), PWM_SPEED_MODE, PWM_TIMER, &rawDivider);
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return rawDivider == (static_cast<uint32_t>(expected) << LEDC_LL_FRACTIONAL_BITS);
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}
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}
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void PwmGenerator::begin() {
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// Match LEDC_SOURCE_CLOCK_HZ and make the timer calculation deterministic.
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ledcSetClockSource(LEDC_USE_XTAL_CLK);
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pinMode(GPIO_PWM, OUTPUT);
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stop();
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}
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bool PwmGenerator::start(uint32_t hz, uint8_t dutyPct, ActualPwm &a) {
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IntegerPwmConfig config = {};
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if (!chooseIntegerPwmConfig(hz, LEDC_SOURCE_CLOCK_HZ, LEDC_MAX_BITS, dutyPct, config)) return false;
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const uint8_t bits = config.bits;
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const uint32_t levels = 1UL << bits;
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const uint32_t duty = (static_cast<uint64_t>(levels) * dutyPct + 50U) / 100U;
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for (uint8_t attempt = 0; attempt < 2; ++attempt) {
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stop();
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const bool attached = ledcAttachChannel(GPIO_PWM, config.actualHz, bits, LEDC_CHANNEL);
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if (attached) {
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// Arduino's LEDC API normally chooses an 8-bit fractional divider.
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// Force the fractional byte to zero so every PWM period contains the
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// same integer number of 40 MHz source-clock ticks.
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setIntegerDivider(config.divider);
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}
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if (attached && integerDividerIsSet(config.divider) && ledcWriteChannel(LEDC_CHANNEL, duty)) {
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// On the first configuration after power-up the duty update is latched
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// on a timer edge. Reading immediately can therefore return zero.
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uint32_t settleUs = static_cast<uint32_t>((2000000ULL + hz - 1U) / hz);
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if (settleUs > 2000U) settleUs = 2000U;
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delayMicroseconds(settleUs);
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const uint32_t actualHz = ledcReadFreq(GPIO_PWM);
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if (actualHz == config.actualHz) {
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a = {hz, actualHz, 100.0f * duty / levels, bits};
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running_ = true;
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return true;
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}
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}
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if (attached) ledcDetach(GPIO_PWM);
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delay(2);
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}
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pinMode(GPIO_PWM, OUTPUT); digitalWrite(GPIO_PWM, PWM_SAFE_LEVEL);
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return false;
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}
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void PwmGenerator::stop() {
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if (running_) ledcDetach(GPIO_PWM);
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pinMode(GPIO_PWM, OUTPUT); digitalWrite(GPIO_PWM, PWM_SAFE_LEVEL);
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running_ = false;
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}
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