pwm_example.zip_DEMO_nrf51822_nrf51822 PWM_蓝牙 PWM

/* Copyright (c) 2009 Nordic Semiconductor. All Rights Reserved. * * The information contained herein is property of Nordic Semiconductor ASA. * Terms and conditions of usage are described in detail in NORDIC * SEMICONDUCTOR STANDARD SOFTWARE LICENSE AGREEMENT. * * Licensees are granted free, non-transferable use of the information. NO * WARRANTY of ANY KIND is provided. This heading must NOT be removed from * the file. * */ /** @file * @defgroup pwm_example_main main.c * @{ * @ingroup pwm_example * * @brief PWM Example Application main file. * * This file contains the source code for a sample application using PWM. * * @image html example_board_setup_a.jpg "Use board setup A for this example." * */ #include <stdbool.h> #include <stdint.h> #include "nrf.h" #include "nrf_assert.h" #include "nrf_gpiote.h" #include "nrf_gpio.h" #include "boards.h" #define PWM_OUTPUT_PIN_NUMBER (LED0) /**< Pin number for PWM output. */ #define MAX_SAMPLE_LEVELS (256UL) /**< Maximum number of sample levels. */ #define TIMER_PRESCALERS 6U /**< Prescaler setting for timer. */ /** @brief Function for getting the next sample. * @return sample_value computed sample. */ static __INLINE uint32_t next_sample_get(void) { static uint32_t sample_value = 8; // Read button input. sample_value = (~NRF_GPIO->IN & 0x000000FFUL); // This is to avoid having two CC events happen at the same time, // CC1 will always create an event on 0 so CC0 and CC2 should not. if (sample_value == 0) { sample_value = 8; } return (uint32_t)sample_value; } /** @brief Function for handling timer 2 peripheral interrupts. */ void TIMER2_IRQHandler(void) { static bool cc0_turn = false; /**< Keeps track of which CC register to be used. */ if ((NRF_TIMER2->EVENTS_COMPARE[1] != 0) && ((NRF_TIMER2->INTENSET & TIMER_INTENSET_COMPARE1_Msk) != 0)) { // Sets the next CC1 value NRF_TIMER2->EVENTS_COMPARE[1] = 0; NRF_TIMER2->CC[1] = (NRF_TIMER2->CC[1] + MAX_SAMPLE_LEVELS); // Every other interrupt CC0 and CC2 will be set to their next values. uint32_t next_sample = next_sample_get(); if (cc0_turn) { NRF_TIMER2->CC[0] = NRF_TIMER2->CC[1] + next_sample; } else { NRF_TIMER2->CC[2] = NRF_TIMER2->CC[1] + next_sample; } // Next turn the other CC will get its value. cc0_turn = !cc0_turn; } } /** @brief Function for initializing the Timer 2 peripheral. */ static void timer2_init(void) { // Start 16 MHz crystal oscillator . NRF_CLOCK->EVENTS_HFCLKSTARTED = 0; NRF_CLOCK->TASKS_HFCLKSTART = 1; // Wait for the external oscillator to start up. while (NRF_CLOCK->EVENTS_HFCLKSTARTED == 0) { //Do nothing. } NRF_TIMER2->MODE = TIMER_MODE_MODE_Timer; NRF_TIMER2->BITMODE = TIMER_BITMODE_BITMODE_16Bit << TIMER_BITMODE_BITMODE_Pos; NRF_TIMER2->PRESCALER = TIMER_PRESCALERS; // Clears the timer, sets it to 0. NRF_TIMER2->TASKS_CLEAR = 1; // Load the initial values to TIMER2 CC registers. NRF_TIMER2->CC[0] = MAX_SAMPLE_LEVELS + next_sample_get(); NRF_TIMER2->CC[1] = MAX_SAMPLE_LEVELS; // CC2 will be set on the first CC1 interrupt. NRF_TIMER2->CC[2] = 0; // Interrupt setup. NRF_TIMER2->INTENSET = (TIMER_INTENSET_COMPARE1_Enabled << TIMER_INTENSET_COMPARE1_Pos); } /** @brief Function for initializing the GPIO Tasks/Events peripheral. */ static void gpiote_init(void) { // Connect GPIO input buffers and configure PWM_OUTPUT_PIN_NUMBER as an output. nrf_gpio_range_cfg_input(BUTTON_START, BUTTON_STOP, NRF_GPIO_PIN_NOPULL); nrf_gpio_cfg_output(PWM_OUTPUT_PIN_NUMBER); NRF_GPIO->OUT = 0x00000000UL; // Configure GPIOTE channel 0 to toggle the PWM pin state // @note Only one GPIOTE task can be connected to an output pin. nrf_gpiote_task_config(0, PWM_OUTPUT_PIN_NUMBER, \ NRF_GPIOTE_POLARITY_TOGGLE, NRF_GPIOTE_INITIAL_VALUE_LOW); } /** @brief Function for initializing the Programmable Peripheral Interconnect peripheral. */ static void ppi_init(void) { // Configure PPI channel 0 to toggle PWM_OUTPUT_PIN on every TIMER2 COMPARE[0] match. NRF_PPI->CH[0].EEP = (uint32_t)&NRF_TIMER2->EVENTS_COMPARE[0]; NRF_PPI->CH[0].TEP = (uint32_t)&NRF_GPIOTE->TASKS_OUT[0]; // Configure PPI channel 1 to toggle PWM_OUTPUT_PIN on every TIMER2 COMPARE[1] match. NRF_PPI->CH[1].EEP = (uint32_t)&NRF_TIMER2->EVENTS_COMPARE[1]; NRF_PPI->CH[1].TEP = (uint32_t)&NRF_GPIOTE->TASKS_OUT[0]; // Configure PPI channel 1 to toggle PWM_OUTPUT_PIN on every TIMER2 COMPARE[2] match. NRF_PPI->CH[2].EEP = (uint32_t)&NRF_TIMER2->EVENTS_COMPARE[2]; NRF_PPI->CH[2].TEP = (uint32_t)&NRF_GPIOTE->TASKS_OUT[0]; // Enable PPI channels 0-2. NRF_PPI->CHEN = (PPI_CHEN_CH0_Enabled << PPI_CHEN_CH0_Pos) | (PPI_CHEN_CH1_Enabled << PPI_CHEN_CH1_Pos) | (PPI_CHEN_CH2_Enabled << PPI_CHEN_CH2_Pos); } /** * @brief Function for application main entry. */ int main(void) { gpiote_init(); ppi_init(); timer2_init(); // Enabling constant latency as indicated by PAN 11 "HFCLK: Base current with HFCLK // running is too high" found at Product Anomaly document found at // https://www.nordicsemi.com/eng/Products/Bluetooth-R-low-energy/nRF51822/#Downloads // // @note This example does not go to low power mode therefore constant latency is not needed. // However this setting will ensure correct behaviour when routing TIMER events through // PPI (shown in this example) and low power mode simultaneously. NRF_POWER->TASKS_CONSTLAT = 1; // Enable interrupt on Timer 2. NVIC_EnableIRQ(TIMER2_IRQn); __enable_irq(); // Start the timer. NRF_TIMER2->TASKS_START = 1; while (true) { // Do nothing. } } /** @} */