1.在sdk_config.h中加入宏
#ifndef PPI_ENABLED #define PPI_ENABLED 1 #endif
// TIMER_ENABLED - nrf_drv_timer - TIMER periperal driver - legacy layer //========================================================== #ifndef TIMER_ENABLED #define TIMER_ENABLED 1 #endif // TIMER_DEFAULT_CONFIG_FREQUENCY - Timer frequency if in Timer mode // 16 MHz // 8 MHz // 4 MHz // 2 MHz // 1 MHz // 500 kHz // 250 kHz // 125 kHz // 62.5 kHz // 31.25 kHz
#ifndef TIMER_DEFAULT_CONFIG_FREQUENCY #define TIMER_DEFAULT_CONFIG_FREQUENCY 4 #endif
// TIMER_DEFAULT_CONFIG_MODE - Timer mode or operation // Timer // Counter
#ifndef TIMER_DEFAULT_CONFIG_MODE #define TIMER_DEFAULT_CONFIG_MODE 0 #endif
// TIMER_DEFAULT_CONFIG_BIT_WIDTH - Timer counter bit width // 16 bit // 8 bit // 24 bit // 32 bit
#ifndef TIMER_DEFAULT_CONFIG_BIT_WIDTH #define TIMER_DEFAULT_CONFIG_BIT_WIDTH 3 #endif
// TIMER_DEFAULT_CONFIG_IRQ_PRIORITY - Interrupt priority
// Priorities 0,2 (nRF51) and 0,1,4,5 (nRF52) are reserved for SoftDevice // 0 (highest) // 1 // 2 // 3 // 4 // 5 // 6 // 7
#ifndef TIMER_DEFAULT_CONFIG_IRQ_PRIORITY #define TIMER_DEFAULT_CONFIG_IRQ_PRIORITY 6 #endif
#ifndef TIMER0_ENABLED #define TIMER0_ENABLED 1 #endif
// TIMER1_ENABLED - Enable TIMER1 instance
#ifndef TIMER1_ENABLED #define TIMER1_ENABLED 1 #endif
// TIMER2_ENABLED - Enable TIMER2 instance
#ifndef TIMER2_ENABLED #define TIMER2_ENABLED 1 #endif
// TIMER3_ENABLED - Enable TIMER3 instance
#ifndef TIMER3_ENABLED #define TIMER3_ENABLED 0 #endif
// TIMER4_ENABLED - Enable TIMER4 instance
#ifndef TIMER4_ENABLED #define TIMER4_ENABLED 0 #endif
2.导入nrfx_ppi.c,nrfx_timer.c,nrf_drv_ppi.c到工程
3.定义时间间隔
#define PPI_EXAMPLE_TIMERS_PHASE_SHIFT_DELAY (10) // 1s = 10 * 100ms (Timer 0 interrupt) #define PPI_EXAMPLE_TIMER0_INTERVAL (100) // Timer interval in milliseconds #define PPI_EXAMPLE_TIMER1_INTERVAL (2000) // Timer interval in milliseconds #define PPI_EXAMPLE_TIMER2_INTERVAL (2000) // Timer interval in milliseconds 4.定义定时器实例 static const nrf_drv_timer_t m_timer0 = NRF_DRV_TIMER_INSTANCE(0); static const nrf_drv_timer_t m_timer1 = NRF_DRV_TIMER_INSTANCE(1); static const nrf_drv_timer_t m_timer2 = NRF_DRV_TIMER_INSTANCE(2); 5.定义变量
static nrf_ppi_channel_t m_ppi_channel1; static nrf_ppi_channel_t m_ppi_channel2;
static volatile uint32_t m_counter;
6.定义PPI事件处理函数
static void timer0_event_handler(nrf_timer_event_t event_type, void * p_context) { ++m_counter; }
/* Timer event handler. Not used since Timer1 and Timer2 are used only for PPI. */ static void empty_timer_handler(nrf_timer_event_t event_type, void * p_context) { }
7.PPI初时化函数
/** @brief Function for initializing the PPI peripheral. */ static void ppi_init(void) { uint32_t err_code = NRF_SUCCESS;
err_code = nrf_drv_ppi_init(); APP_ERROR_CHECK(err_code);
/* Configure 1st available PPI channel to stop TIMER0 counter on TIMER1 COMPARE[0] match, * which is every even number of seconds. */ err_code = nrf_drv_ppi_channel_alloc(&m_ppi_channel1); APP_ERROR_CHECK(err_code); err_code = nrf_drv_ppi_channel_assign(m_ppi_channel1, nrf_drv_timer_event_address_get(&m_timer1, NRF_TIMER_EVENT_COMPARE0), nrf_drv_timer_task_address_get(&m_timer0, NRF_TIMER_TASK_STOP)); APP_ERROR_CHECK(err_code);
/* Configure 2nd available PPI channel to start TIMER0 counter at TIMER2 COMPARE[0] match, * which is every odd number of seconds. */ err_code = nrf_drv_ppi_channel_alloc(&m_ppi_channel2); APP_ERROR_CHECK(err_code); err_code = nrf_drv_ppi_channel_assign(m_ppi_channel2, nrf_drv_timer_event_address_get(&m_timer2, NRF_TIMER_EVENT_COMPARE0), nrf_drv_timer_task_address_get(&m_timer0, NRF_TIMER_TASK_START)); APP_ERROR_CHECK(err_code);
// Enable both configured PPI channels err_code = nrf_drv_ppi_channel_enable(m_ppi_channel1); APP_ERROR_CHECK(err_code); err_code = nrf_drv_ppi_channel_enable(m_ppi_channel2); APP_ERROR_CHECK(err_code); } 8.定时器初时化
/** @brief Function for Timer 0 initialization. * @details Timer 0 will be stopped and started by Timer 1 and Timer 2 respectively using PPI. * It is configured to generate an interrupt every 100ms. */ static void timer0_init(void) { // Check TIMER0 configuration for details. nrf_drv_timer_config_t timer_cfg = NRF_DRV_TIMER_DEFAULT_CONFIG; timer_cfg.frequency = NRF_TIMER_FREQ_31250Hz; ret_code_t err_code = nrf_drv_timer_init(&m_timer0, &timer_cfg, timer0_event_handler); APP_ERROR_CHECK(err_code);
nrf_drv_timer_extended_compare(&m_timer0, NRF_TIMER_CC_CHANNEL0, nrf_drv_timer_ms_to_ticks(&m_timer0, PPI_EXAMPLE_TIMER0_INTERVAL), NRF_TIMER_SHORT_COMPARE0_CLEAR_MASK, true); }
/** @brief Function for Timer 1 initialization. * @details Initializes TIMER1 peripheral to generate an event every 2 seconds. The events are * generated at even numbers of seconds after starting the example (2, 4, 6 ...) and they * are used to stop TIMER0 via PPI: TIMER1->EVENT_COMPARE[0] triggers TIMER0->TASK_STOP. */ static void timer1_init(void) { // Check TIMER1 configuration for details. nrf_drv_timer_config_t timer_cfg = NRF_DRV_TIMER_DEFAULT_CONFIG; timer_cfg.frequency = NRF_TIMER_FREQ_31250Hz; ret_code_t err_code = nrf_drv_timer_init(&m_timer1, &timer_cfg, empty_timer_handler); APP_ERROR_CHECK(err_code);
nrf_drv_timer_extended_compare(&m_timer1, NRF_TIMER_CC_CHANNEL0, nrf_drv_timer_ms_to_ticks(&m_timer1, PPI_EXAMPLE_TIMER1_INTERVAL), NRF_TIMER_SHORT_COMPARE0_CLEAR_MASK, false); }
/** @brief Function for Timer 2 initialization. * @details Initializes TIMER2 peripheral to generate an event every 2 seconds. The events are * generated at odd numbers of seconds after starting the example (3, 5, 7 ...) and they * are used to start TIMER0 via PPI: TIMER2->EVENT_COMPARE[0] triggers TIMER0->TASK_START. */ static void timer2_init(void) { // Check TIMER2 configuration for details. nrf_drv_timer_config_t timer_cfg = NRF_DRV_TIMER_DEFAULT_CONFIG; timer_cfg.frequency = NRF_TIMER_FREQ_31250Hz; ret_code_t err_code = nrf_drv_timer_init(&m_timer2, &timer_cfg, empty_timer_handler); APP_ERROR_CHECK(err_code);
nrf_drv_timer_extended_compare(&m_timer2, NRF_TIMER_CC_CHANNEL0, nrf_drv_timer_ms_to_ticks(&m_timer2, PPI_EXAMPLE_TIMER2_INTERVAL), NRF_TIMER_SHORT_COMPARE0_CLEAR_MASK, false); } 9.主函数处理
/** * @brief Function for main application entry. */ int main(void) { uint32_t err_code; uint32_t old_val = 0; bsp_board_init(BSP_INIT_LEDS);
const app_uart_comm_params_t comm_params = { RX_PIN_NUMBER, TX_PIN_NUMBER, RTS_PIN_NUMBER, CTS_PIN_NUMBER, UART_HWFC, false, #if defined (UART_PRESENT) NRF_UART_BAUDRATE_115200 #else NRF_UARTE_BAUDRATE_115200 #endif };
APP_UART_FIFO_INIT(&comm_params, UART_RX_BUF_SIZE, UART_TX_BUF_SIZE, uart_error_handle, APP_IRQ_PRIORITY_LOWEST, err_code);
APP_ERROR_CHECK(err_code);
ppi_init(); timer0_init(); // Timer used to increase m_counter every 100ms. timer1_init(); // Timer to generate events on even number of seconds - stopping Timer 0 timer2_init(); // Timer to generate events on odd number of seconds - starting Timer 0
printf("PPI example started.");
// Start clock. nrf_drv_timer_enable(&m_timer0);
/* Below delay is implemented to ensure that Timer0 interrupt will execute before PPI action. * Please be aware that such solution was tested only in this simple example code. In case * of more complex systems with higher level interrupts this may lead to not correct timers * synchronization. */ nrf_delay_us(5); nrf_drv_timer_enable(&m_timer1);
m_counter = (uint32_t)-PPI_EXAMPLE_TIMERS_PHASE_SHIFT_DELAY;
// Timer 2 will start one second after Timer 1 (m_counter will equal 0 after 1s) while (m_counter != 0) { // just wait } nrf_drv_timer_enable(&m_timer2);
while (true) { uint32_t counter = m_counter; if (old_val != counter) { old_val = counter;
printf("Current count: %u\r\n", counter); } }
}
