sd_app_evt_wait cause uart not work.

[tianbing357]

Hi, I use nrf52832's uart with a simple driver, not "nrf_drv_uart", because I don't know how to use receive and transmit interruption with "nrf_drv_uart". the uart drive i used is bellow:

void drv_uart_init(void)
{ 
 init_io();
 init_uart();
}

static void init_io(void)
{ 
 nrf_gpio_cfg_output(UART_TX);
 nrf_gpio_pin_set(UART_TX);
 nrf_gpio_cfg_input( UART_RX,NRF_GPIO_PIN_PULLUP);
}

static void init_uart(void)
{
 NRF_UART0->BAUDRATE = DEFAULT_BAUD;
 
 NRF_UART0->PSELTXD = UART_TX;
 NRF_UART0->PSELRXD = UART_RX;
 
 enable_interrupt();
 // ????
 NRF_UART0->ENABLE = UART_ENABLE_ENABLE_Enabled;
 NRF_UART0->TASKS_STARTTX = 1;
 NRF_UART0->TASKS_STARTRX = 1;
}

static void enable_interrupt(void)
{
 NRF_UART0->EVENTS_RXDRDY = 0;  
 NRF_UART0->INTENSET = (UART_INTENSET_RXDRDY_Enabled << UART_INTENSET_RXDRDY_Pos)|(UART_INTENSET_TXDRDY_Enabled << UART_INTENSET_TXDRDY_Pos);
 
 NVIC_SetPriority(UART0_IRQn, 7);
    NVIC_ClearPendingIRQ(UART0_IRQn);
    NVIC_EnableIRQ(UART0_IRQn);
}

void UARTE0_UART0_IRQHandler(void)
{
 if(NRF_UART0->EVENTS_RXDRDY==1)
 {
  NRF_UART0->EVENTS_RXDRDY = 0;
  *m_p_rx_buf=NRF_UART0->RXD;
  m_p_rx_buf++;
  *m_p_rx_len=*m_p_rx_len+1;
 }
 if(NRF_UART0->EVENTS_TXDRDY==1)
 {
  NRF_UART0->EVENTS_TXDRDY = 0;
  if(m_tx_len>0)
  {
   NRF_UART0->TXD = *m_p_tx_buf;
   m_p_tx_buf++;
   m_tx_len=m_tx_len-1;
  }
 }
}

In the idle hook function, I call nrf_pwr_mgmt_run(), as follows:

void vApplicationIdleHook( void )
{
  nrf_pwr_mgmt_run();
}

when I remove "nrf_pwr_mgmt_run();", or remove "ret_code_t ret_code = sd_app_evt_wait();" in the nrf_pwr_mgmt_run function, the uart can work correctly,  I can receive all data on my computer, but when i use "nrf_pwr_mgmt_run" or "sd_app_evt_wait", the uart cannot work, i receive no data on my computer.

why?

[Susheel Nuguru]

You made me read twice to see the function vApplicationIdleHook and figure out that you are using FreeRTOS. 

Well the simple uart needs CPU to be awake to trigger send/receive as you are not using EasyDMA to push pop data from the UART FIFO to/from the RAM.

In which context are you transmitting data? when you make the chip go to sleep, are you expecting the data transfer to be triggered in some other interrupt context?

[tianbing357]

i tried, #define configUSE_TICKLESS_IDLE 1 , the power consumption is much higher than sd_app_evt_wait() ,i use SDK 14.2.

when use __WFE(); as follows:

void vApplicationIdleHook( void )
{
do{
__WFE();
} while (0 == (NVIC->ISPR[0] | NVIC->ISPR[1]));
}

the power consumption is a little higher than sd_app_evt_wait(). why?

[Susheel Nuguru]

I would strongly recommend you to download SDK15.3 and replace your SDK14\external\freertos folder with the SDK15.3\external\freertos folder. There were a couple of fixes that came later.

[tianbing357]

i did as your advise, but it still not worked, the current is 7mA when use "#define configUSE_TICKLESS_IDLE 1", but 2mA use __WFE();

[Susheel Nuguru]

You should not use nrf_pwr_mgmt_run  in vApplicationIdleHook when you are using tickless_dile. Can you please comment it? 

I am also assuming that you are testing this on the PCA10040 development kit. 

If the above suggestion did not help you, then I need to get your project to be able to reproduce it and give you a proper workaround.