68 lines
No EOL
2.3 KiB
C
68 lines
No EOL
2.3 KiB
C
#include "prst/pwm.h"
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#include <app_error.h>
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#include <nordic_common.h>
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#include <nrf_drv_pwm.h>
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#include <nrf_log.h>
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#include <nrf_pwm.h>
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#include "prst_config.h"
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// Each step in the counter will take 1/16e6 s.
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#define PRST_PWM_BASE_FREQ NRF_PWM_CLK_16MHz
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// We will count up to 16. It will take 1us at 16MHz.
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// With the NRF_PWM_MODE_UP_AND_DOWN count mode, we assume 1us is half the
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// output PWM period (total 2us => 500MHz frequency). We set a duty cycle of
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// 50% below with PRST_PWM_FLIP_AT_COUNT to be half the max count.
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#define PRST_PWM_MAX_COUNT 16
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// We will toggle the PWM output when we reach this count.
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// #define PRST_PWM_FLIP_AT_COUNT PRST_PWM_MAX_COUNT / 2
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#define PRST_PWM_FLIP_AT_COUNT 8
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static nrf_drv_pwm_t m_pwm0 = NRF_DRV_PWM_INSTANCE(0);
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static nrf_pwm_values_common_t seq_values_[] = {PRST_PWM_FLIP_AT_COUNT};
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static const nrf_pwm_sequence_t seq_ = {
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.values.p_common = seq_values_,
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.length = NRF_PWM_VALUES_LENGTH(seq_values_),
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.repeats = 0,
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.end_delay = 0};
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void prst_pwm_init() {
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// We set the PWM pin as output so we can control its state after the PWM is
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// stopped. Without this, I'm seeing the PWM pin remaining high after stopped.
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nrf_gpio_pin_dir_set(PRST_PWM_PIN, NRF_GPIO_PIN_DIR_OUTPUT);
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nrf_drv_pwm_config_t const config0 = {
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// We have to specify the state of the 4 channels. We only care about the
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// first one, so we set all others to not used.
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.output_pins =
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{
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PRST_PWM_PIN | NRF_DRV_PWM_PIN_INVERTED,
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NRF_DRV_PWM_PIN_NOT_USED,
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NRF_DRV_PWM_PIN_NOT_USED,
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NRF_DRV_PWM_PIN_NOT_USED,
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},
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.irq_priority = APP_IRQ_PRIORITY_LOWEST,
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// This is the hal PRESCALER
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.base_clock = NRF_PWM_CLK_16MHz,
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.count_mode = NRF_PWM_MODE_UP_AND_DOWN,
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// This is the hal COUNTERTOP.
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.top_value = PRST_PWM_MAX_COUNT,
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.load_mode = NRF_PWM_LOAD_COMMON,
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.step_mode = NRF_PWM_STEP_AUTO};
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APP_ERROR_CHECK(nrf_drv_pwm_init(&m_pwm0, &config0, NULL));
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}
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void prst_pwm_start() {
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// Loop until stopped.
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APP_ERROR_CHECK(
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nrf_drv_pwm_simple_playback(&m_pwm0, &seq_, 1, NRF_DRV_PWM_FLAG_LOOP));
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}
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void prst_pwm_stop() {
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nrf_drv_pwm_stop(&m_pwm0, /*wait_until_stopped=*/true);
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nrf_drv_pwm_uninit(&m_pwm0);
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nrf_gpio_pin_clear(PRST_PWM_PIN);
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} |