GPIO and UART with low power consumption?

[HelloWorld]

I am trying to run below 10 uA with code below while GPIO and uart are on. Sleep mode is applied (below 10 uA), and only wakes up when button is pressed (can be higher amps)

lfclk_config();
rtc_config();	
gpio_init();

uint32_t err_code;

    const app_uart_comm_params_t comm_params =
  {
      RX_PIN_NUMBER,
      TX_PIN_NUMBER,
      RTS_PIN_NUMBER,
      CTS_PIN_NUMBER,
      APP_UART_FLOW_CONTROL_ENABLED,
      false,
      UART_BAUDRATE_BAUDRATE_Baud115200
  };
		
		APP_UART_FIFO_INIT(&comm_params,
                     UART_RX_BUF_SIZE,
                     UART_TX_BUF_SIZE,
                     uart_error_handle,
                     APP_IRQ_PRIORITY_LOWEST,
                     err_code);

However, it still runs 2.5mA. Am I making some mistake here? thanks

[Hung Bui]

Hi,

If you have a look at app_uart_init() which is called by APP_UART_FIFO_INIT, you can find that nrf_drv_uart_rx_enable() is called by default.

With RX enabled the UART will keep the 16Mhz oscillator running and the regulators in addition.

Have you tried to call nrf_drv_uart_rx_disable() after you call APP_UART_FIFO_INIT to put the UART in idle mode ?

What exactly inside the gpioi_init() ? Do you use GPIOTE pin interrupt ?

[Hung Bui]

Hi again,

Another tip is to disable EASYDMA , it can consume a lot of power compare to letting the CPU handle the incoming data.

[HelloWorld]

what does EASYDMA do exactly? and where can i disable it?

[Hung Bui]

Please have a look at the nRF52 product spec at chapter 10 and chapter 35.2

To disable EasyDMA on the UART driver, turn off UART0_CONFIG_USE_EASY_DMA in sdk_config.h as told here.

[Nate]

Did you figure this out? I am running into the same issues with power and the uart and my numbers are almost the same as yours as far as power with the uart enabled and disabled

[Hung Bui]

@Nate: Have you looked at the spec on current consumption for EasyDMA ? It's actually lower power consumption to use the CPU to handle UART shortly.