nrf52832 ADC for ppi

1.在sdk_config.h中加入宏

// SAADC_ENABLED - nrf_drv_saadc - SAADC peripheral driver - legacy layer
//==========================================================
#ifndef SAADC_ENABLED
#define SAADC_ENABLED 1
#endif
// SAADC_CONFIG_RESOLUTION  - Resolution
 
// <0=> 8 bit 
// <1=> 10 bit 
// <2=> 12 bit 
// <3=> 14 bit 

#ifndef SAADC_CONFIG_RESOLUTION
#define SAADC_CONFIG_RESOLUTION 2
#endif

// SAADC_CONFIG_OVERSAMPLE  - Sample period
 
// <0=> Disabled 
// <1=> 2x 
// <2=> 4x 
// <3=> 8x 
// <4=> 16x 
// <5=> 32x 
// <6=> 64x 
// <7=> 128x 
// <8=> 256x 

#ifndef SAADC_CONFIG_OVERSAMPLE
#define SAADC_CONFIG_OVERSAMPLE 0
#endif

// SAADC_CONFIG_LP_MODE  - Enabling low power mode
 

#ifndef SAADC_CONFIG_LP_MODE
#define SAADC_CONFIG_LP_MODE 0
#endif

// SAADC_CONFIG_IRQ_PRIORITY  - Interrupt priority
 

// Priorities 0,2 (nRF51) and 0,1,4,5 (nRF52) are reserved for SoftDevice
// <0=> 0 (highest) 
// <1=> 1 
// <2=> 2 
// <3=> 3 
// <4=> 4 
// <5=> 5 
// <6=> 6 
// <7=> 7 

#ifndef SAADC_CONFIG_IRQ_PRIORITY
#define SAADC_CONFIG_IRQ_PRIORITY 6
#endif

#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
 
// <0=> 16 MHz 
// <1=> 8 MHz 
// <2=> 4 MHz 
// <3=> 2 MHz 
// <4=> 1 MHz 
// <5=> 500 kHz 
// <6=> 250 kHz 
// <7=> 125 kHz 
// <8=> 62.5 kHz 
// <9=> 31.25 kHz 

#ifndef TIMER_DEFAULT_CONFIG_FREQUENCY
#define TIMER_DEFAULT_CONFIG_FREQUENCY 4
#endif

// TIMER_DEFAULT_CONFIG_MODE  - Timer mode or operation
 
// <0=> Timer 
// <1=> Counter 

#ifndef TIMER_DEFAULT_CONFIG_MODE
#define TIMER_DEFAULT_CONFIG_MODE 0
#endif

// TIMER_DEFAULT_CONFIG_BIT_WIDTH  - Timer counter bit width
 
// <0=> 16 bit 
// <1=> 8 bit 
// <2=> 24 bit 
// <3=> 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=> 0 (highest) 
// <1=> 1 
// <2=> 2 
// <3=> 3 
// <4=> 4 
// <5=> 5 
// <6=> 6 
// <7=> 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.导入文件nrfx_ssadc.c,nrfx_ppi.c,nrf_drv_ppi.c,nrfx_timer.c到工程

3.引入头文件

#include "nrf_drv_saadc.h"
#include "nrf_drv_ppi.h"
#include "nrf_drv_timer.h"

4.定义变量及宏
#define SAMPLES_IN_BUFFER 1
volatile uint8_t state = 1;

static const nrf_drv_timer_t m_timer = NRF_DRV_TIMER_INSTANCE(0);
static nrf_saadc_value_t     m_buffer_pool[2][SAMPLES_IN_BUFFER];
static nrf_ppi_channel_t     m_ppi_channel;
static uint32_t              m_adc_evt_counter;
5.事件处理函数
void timer_handler(nrf_timer_event_t event_type, void * p_context)
{

}

void saadc_callback(nrf_drv_saadc_evt_t const * p_event)
{
    if (p_event->type == NRF_DRV_SAADC_EVT_DONE)
    {
        ret_code_t err_code;

        err_code = nrf_drv_saadc_buffer_convert(p_event->data.done.p_buffer, SAMPLES_IN_BUFFER);
        APP_ERROR_CHECK(err_code);

        int i;
        printf("ADC event number: %d\n", (int)m_adc_evt_counter);

        for (i = 0; i < SAMPLES_IN_BUFFER; i++)
        {
            printf("%d", p_event->data.done.p_buffer[i]);
        }
        m_adc_evt_counter++;
    }
}
6.初时化函数

void saadc_sampling_event_init(void)
{
    ret_code_t err_code;

    err_code = nrf_drv_ppi_init();
    APP_ERROR_CHECK(err_code);

    nrf_drv_timer_config_t timer_cfg = NRF_DRV_TIMER_DEFAULT_CONFIG;
    timer_cfg.bit_width = NRF_TIMER_BIT_WIDTH_32;
    err_code = nrf_drv_timer_init(&m_timer, &timer_cfg, timer_handler);
    APP_ERROR_CHECK(err_code);

    /* setup m_timer for compare event every 400ms */
    uint32_t ticks = nrf_drv_timer_ms_to_ticks(&m_timer, 5000);
    nrf_drv_timer_extended_compare(&m_timer,
                                   NRF_TIMER_CC_CHANNEL0,
                                   ticks,
                                   NRF_TIMER_SHORT_COMPARE0_CLEAR_MASK,
                                   false);
    nrf_drv_timer_enable(&m_timer);

    uint32_t timer_compare_event_addr = nrf_drv_timer_compare_event_address_get(&m_timer,
                                                                                NRF_TIMER_CC_CHANNEL0);
    uint32_t saadc_sample_task_addr   = nrf_drv_saadc_sample_task_get();

    /* setup ppi channel so that timer compare event is triggering sample task in SAADC */
    err_code = nrf_drv_ppi_channel_alloc(&m_ppi_channel);
    APP_ERROR_CHECK(err_code);

    err_code = nrf_drv_ppi_channel_assign(m_ppi_channel,
                                          timer_compare_event_addr,
                                          saadc_sample_task_addr);
    APP_ERROR_CHECK(err_code);
}

void saadc_sampling_event_enable(void)
{
    ret_code_t err_code = nrf_drv_ppi_channel_enable(m_ppi_channel);

    APP_ERROR_CHECK(err_code);
}
7.在主函数处理
    saadc_init();
    saadc_sampling_event_init();
    saadc_sampling_event_enable();