【Question】：I want to use timer+ppi+SPI(with DMA) write DAC, but now something is wrong, when timer trigger the SPI to write DAC through PPI, it can call the "spi_event_handler" after the SPI write is finished, and NRF_SPIM2->TXD.PTR increases normally in the "spi_event_handler" ,but there is still no output in DAC; Ireally do not know what's wrong. When I use timer+SPI write DAC, everything is OK. Please help me, thanks. The following is code:
//定义定时器配置结构体，并使用默认配置参数初始化结构体
nrf_drv_timer_config_t timer_cfg =NRF_DRV_TIMER_DEFAULT_CONFIG;
//初始化定时器，初始化时会注册timer_led_event_handler事件回调函数
err_code = nrf_drv_timer_init(&TIMER_DAC, &timer_cfg, timer_DAC_event_handler);
APP_ERROR_CHECK(err_code);
//定时时间(单位us)转换为ticks
time_ticks = nrf_drv_timer_us_to_ticks(&TIMER_DAC, time_us);
printf("time_us= %d,time_ticks= %d \r\n",time_us,time_ticks);
//设置定时器捕获/比较通道及该通道的比较值，使能通道的比较中断
nrf_drv_timer_extended_compare(
&TIMER_DAC, NRF_TIMER_CC_CHANNEL0, time_ticks, NRF_TIMER_SHORT_COMPARE0_CLEAR_MASK, false);
/* 初始化SPI2 */
nrf_drv_spi_config_t spi_config = NRF_DRV_SPI_DEFAULT_CONFIG;
spi_config.mosi_pin = DAC_SPI_MOSI;
spi_config.sck_pin = DAC_SPI_SCK;
spi_config.ss_pin = DAC_SPI_SS;
nrf_gpio_cfg_output(DAC_SPI_SS);
spi_config.frequency= NRF_SPI_FREQ_8M;
APP_ERROR_CHECK(nrf_drv_spi_init(&DAC_spi, &spi_config, spi_event_handler));
DAC_SPIDMA_Init();
printf("DAC_SPI_Init OK \r\n");
nrf_delay_ms(500);
//关联SPI DMA缓存
NRF_SPIM2->TXD.MAXCNT = 2;
// NRF_SPIM2->RXD.MAXCNT = 2;
NRF_SPIM2->TXD.LIST=1;
NRF_SPIM2->TXD.PTR=(uint32_t)&SPI2ArrayList; //SPI2ArrayList;
//初始化PPI程序模块
uint32_t err_code = NRF_SUCCESS;
err_code = nrf_drv_ppi_init();
APP_ERROR_CHECK(err_code);
//分配PPI通道，注意PPI通道的分配是由驱动函数完成的，分配的通道号保存到my_ppi_channel
err_code = nrf_drv_ppi_channel_alloc(&timer2DAC_ppi_channel);
APP_ERROR_CHECK(err_code);
//分配PPI通道的EEP和TEP
err_code = nrf_drv_ppi_channel_assign(timer2DAC_ppi_channel,
nrf_drv_timer_compare_event_address_get(&TIMER_DAC,NRF_TIMER_CC_CHANNEL0),
nrf_drv_spi_start_task_get(&DAC_spi));
// nrf_drv_gpiote_out_task_addr_get(LED_2)
APP_ERROR_CHECK(err_code);
//使能PPI通道
err_code = nrf_drv_ppi_channel_enable(timer2DAC_ppi_channel);
APP_ERROR_CHECK(err_code);
printf("PPI enable OK \r\n");
nrf_drv_timer_enable(&TIMER_DAC);
printf("nrf_drv_timer_enable OK \r\n");
void spi_event_handler(nrf_drv_spi_evt_t const * p_event)
{
uint8_t i=0;
DAC_COUNT++;
if(DAC_COUNT==DAC_NUMBER)
{
DAC_COUNT=0;
NRF_SPIM2->TXD.PTR=(uint32_t)&SPI2ArrayList;
}
printf("NRF_SPIM2->TXD.AMCOUNT= %d \r\n",NRF_SPIM2->TXD.AMOUNT);
printf("NRF_SPIM2->TXD.PTR = %x \r\n", NRF_SPIM2->TXD.PTR);
}
typedef struct ArrayList
{
uint8_t buffer[2];
} ArrayList_type;
ArrayList_type SPI2ArrayList[8];
