246 lines
9.8 KiB
C
246 lines
9.8 KiB
C
/**
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* Copyright (c) 2014 - 2020, Nordic Semiconductor ASA
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*
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without modification,
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* are permitted provided that the following conditions are met:
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*
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* 1. Redistributions of source code must retain the above copyright notice, this
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* list of conditions and the following disclaimer.
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*
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* 2. Redistributions in binary form, except as embedded into a Nordic
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* Semiconductor ASA integrated circuit in a product or a software update for
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* such product, must reproduce the above copyright notice, this list of
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* conditions and the following disclaimer in the documentation and/or other
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* materials provided with the distribution.
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*
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* 3. Neither the name of Nordic Semiconductor ASA nor the names of its
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* contributors may be used to endorse or promote products derived from this
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* software without specific prior written permission.
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*
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* 4. This software, with or without modification, must only be used with a
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* Nordic Semiconductor ASA integrated circuit.
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*
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* 5. Any software provided in binary form under this license must not be reverse
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* engineered, decompiled, modified and/or disassembled.
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*
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* THIS SOFTWARE IS PROVIDED BY NORDIC SEMICONDUCTOR ASA "AS IS" AND ANY EXPRESS
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* OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY, NONINFRINGEMENT, AND FITNESS FOR A PARTICULAR PURPOSE ARE
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* DISCLAIMED. IN NO EVENT SHALL NORDIC SEMICONDUCTOR ASA OR CONTRIBUTORS BE
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* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
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* GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
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* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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*/
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/** @file
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*
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* @defgroup ppi_example_main main.c
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* @{
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* @ingroup ppi_example
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* @brief PPI Example Application main file.
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*
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* This file contains the source code for a sample application using PPI to communicate between timers.
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*
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*/
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#include <stdint.h>
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#include "nrf_delay.h"
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#include "app_error.h"
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#include "nrf_drv_ppi.h"
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#include "nrf_drv_timer.h"
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#include "nrf_log.h"
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#include "nrf_log_ctrl.h"
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#include "nrf_log_default_backends.h"
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#define PPI_EXAMPLE_TIMERS_PHASE_SHIFT_DELAY (10) // 1s = 10 * 100ms (Timer 0 interrupt)
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#define PPI_EXAMPLE_TIMER0_INTERVAL (100) // Timer interval in milliseconds
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#define PPI_EXAMPLE_TIMER1_INTERVAL (2000) // Timer interval in milliseconds
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#define PPI_EXAMPLE_TIMER2_INTERVAL (2000) // Timer interval in milliseconds
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static const nrf_drv_timer_t m_timer0 = NRF_DRV_TIMER_INSTANCE(0);
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static const nrf_drv_timer_t m_timer1 = NRF_DRV_TIMER_INSTANCE(1);
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static const nrf_drv_timer_t m_timer2 = NRF_DRV_TIMER_INSTANCE(2);
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static nrf_ppi_channel_t m_ppi_channel1;
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static nrf_ppi_channel_t m_ppi_channel2;
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static volatile uint32_t m_counter;
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static void timer0_event_handler(nrf_timer_event_t event_type, void * p_context)
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{
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++m_counter;
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}
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/* Timer event handler. Not used since Timer1 and Timer2 are used only for PPI. */
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static void empty_timer_handler(nrf_timer_event_t event_type, void * p_context)
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{
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}
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/** @brief Function for initializing the PPI peripheral.
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*/
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static void ppi_init(void)
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{
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uint32_t err_code = NRF_SUCCESS;
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err_code = nrf_drv_ppi_init();
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APP_ERROR_CHECK(err_code);
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/* Configure 1st available PPI channel to stop TIMER0 counter on TIMER1 COMPARE[0] match,
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* which is every even number of seconds.
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*/
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err_code = nrf_drv_ppi_channel_alloc(&m_ppi_channel1);
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APP_ERROR_CHECK(err_code);
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err_code = nrf_drv_ppi_channel_assign(m_ppi_channel1,
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nrf_drv_timer_event_address_get(&m_timer1,
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NRF_TIMER_EVENT_COMPARE0),
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nrf_drv_timer_task_address_get(&m_timer0,
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NRF_TIMER_TASK_STOP));
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APP_ERROR_CHECK(err_code);
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/* Configure 2nd available PPI channel to start TIMER0 counter at TIMER2 COMPARE[0] match,
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* which is every odd number of seconds.
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*/
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err_code = nrf_drv_ppi_channel_alloc(&m_ppi_channel2);
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APP_ERROR_CHECK(err_code);
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err_code = nrf_drv_ppi_channel_assign(m_ppi_channel2,
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nrf_drv_timer_event_address_get(&m_timer2,
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NRF_TIMER_EVENT_COMPARE0),
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nrf_drv_timer_task_address_get(&m_timer0,
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NRF_TIMER_TASK_START));
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APP_ERROR_CHECK(err_code);
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// Enable both configured PPI channels
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err_code = nrf_drv_ppi_channel_enable(m_ppi_channel1);
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APP_ERROR_CHECK(err_code);
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err_code = nrf_drv_ppi_channel_enable(m_ppi_channel2);
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APP_ERROR_CHECK(err_code);
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}
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/** @brief Function for Timer 0 initialization.
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* @details Timer 0 will be stopped and started by Timer 1 and Timer 2 respectively using PPI.
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* It is configured to generate an interrupt every 100ms.
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*/
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static void timer0_init(void)
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{
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// Check TIMER0 configuration for details.
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nrf_drv_timer_config_t timer_cfg = NRF_DRV_TIMER_DEFAULT_CONFIG;
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timer_cfg.frequency = NRF_TIMER_FREQ_31250Hz;
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ret_code_t err_code = nrf_drv_timer_init(&m_timer0, &timer_cfg, timer0_event_handler);
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APP_ERROR_CHECK(err_code);
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nrf_drv_timer_extended_compare(&m_timer0,
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NRF_TIMER_CC_CHANNEL0,
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nrf_drv_timer_ms_to_ticks(&m_timer0,
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PPI_EXAMPLE_TIMER0_INTERVAL),
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NRF_TIMER_SHORT_COMPARE0_CLEAR_MASK,
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true);
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}
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/** @brief Function for Timer 1 initialization.
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* @details Initializes TIMER1 peripheral to generate an event every 2 seconds. The events are
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* generated at even numbers of seconds after starting the example (2, 4, 6 ...) and they
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* are used to stop TIMER0 via PPI: TIMER1->EVENT_COMPARE[0] triggers TIMER0->TASK_STOP.
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*/
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static void timer1_init(void)
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{
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// Check TIMER1 configuration for details.
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nrf_drv_timer_config_t timer_cfg = NRF_DRV_TIMER_DEFAULT_CONFIG;
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timer_cfg.frequency = NRF_TIMER_FREQ_31250Hz;
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ret_code_t err_code = nrf_drv_timer_init(&m_timer1, &timer_cfg, empty_timer_handler);
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APP_ERROR_CHECK(err_code);
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nrf_drv_timer_extended_compare(&m_timer1,
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NRF_TIMER_CC_CHANNEL0,
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nrf_drv_timer_ms_to_ticks(&m_timer1,
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PPI_EXAMPLE_TIMER1_INTERVAL),
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NRF_TIMER_SHORT_COMPARE0_CLEAR_MASK,
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false);
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}
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/** @brief Function for Timer 2 initialization.
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* @details Initializes TIMER2 peripheral to generate an event every 2 seconds. The events are
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* generated at odd numbers of seconds after starting the example (3, 5, 7 ...) and they
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* are used to start TIMER0 via PPI: TIMER2->EVENT_COMPARE[0] triggers TIMER0->TASK_START.
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*/
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static void timer2_init(void)
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{
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// Check TIMER2 configuration for details.
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nrf_drv_timer_config_t timer_cfg = NRF_DRV_TIMER_DEFAULT_CONFIG;
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timer_cfg.frequency = NRF_TIMER_FREQ_31250Hz;
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ret_code_t err_code = nrf_drv_timer_init(&m_timer2, &timer_cfg, empty_timer_handler);
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APP_ERROR_CHECK(err_code);
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nrf_drv_timer_extended_compare(&m_timer2,
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NRF_TIMER_CC_CHANNEL0,
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nrf_drv_timer_ms_to_ticks(&m_timer2,
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PPI_EXAMPLE_TIMER2_INTERVAL),
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NRF_TIMER_SHORT_COMPARE0_CLEAR_MASK,
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false);
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}
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/**
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* @brief Function for application main entry.
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*/
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int main(void)
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{
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uint32_t old_val = 0;
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uint32_t err_code;
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err_code = NRF_LOG_INIT(NULL);
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APP_ERROR_CHECK(err_code);
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NRF_LOG_DEFAULT_BACKENDS_INIT();
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ppi_init();
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timer0_init(); // Timer used to increase m_counter every 100ms.
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timer1_init(); // Timer to generate events on even number of seconds - stopping Timer 0
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timer2_init(); // Timer to generate events on odd number of seconds - starting Timer 0
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NRF_LOG_INFO("PPI example started.");
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// Start clock.
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nrf_drv_timer_enable(&m_timer0);
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/* Below delay is implemented to ensure that Timer0 interrupt will execute before PPI action.
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* Please be aware that such solution was tested only in this simple example code. In case
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* of more complex systems with higher level interrupts this may lead to not correct timers
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* synchronization.
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*/
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nrf_delay_us(5);
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nrf_drv_timer_enable(&m_timer1);
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m_counter = (uint32_t)-PPI_EXAMPLE_TIMERS_PHASE_SHIFT_DELAY;
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// Timer 2 will start one second after Timer 1 (m_counter will equal 0 after 1s)
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while (m_counter != 0)
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{
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// just wait
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}
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nrf_drv_timer_enable(&m_timer2);
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while (true)
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{
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uint32_t counter = m_counter;
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if (old_val != counter)
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{
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old_val = counter;
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NRF_LOG_INFO("Current count: %u", counter);
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NRF_LOG_FLUSH();
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}
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}
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}
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/** @} */
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