nrf52 UARTE/Fifo high current consumption

[OskarM]

I am struggling with excess current consupmtion using uart+fifo. It seems like ~300uA is drawn by UART and disabling via app_uart_close() doesn't help.

I have checked all possible configurations of below params:

#define UART0_CONFIG_USE_EASY_DMA false
//Compile time flag
#define UART_EASY_DMA_SUPPORT     1
#define UART_LEGACY_SUPPORT       1
#endif //NRF52

and after uart_close() current jumps to 2mA and stays there for a while and goes back to the same value of ~300uA; I am pretty sure its UART - I can comment it out and current stasy at very low levels.

I have tried different settings and UARTE/UART mixing but it only makes it worse if I ie. use only easy_dma. Any suggestions ? Errata?

I use SDK12, with SD132, sd is enabled, but no advertsing.

[Stefan Birnir Sverrisson]

Hi Oskar

I do not experience the same as you on nRF52. If I try out the standard ble_app_uart example in SDK 12.0.0 and I add app_uart_close() a at the end of the initialization in main but before the main loop then I get low current consumption. If I also dont start advertising I get ~2uA current consumption:

...
advertising_init();
conn_params_init();

//    printf("\r\nUART Start!\r\n");
//    err_code = ble_advertising_start(BLE_ADV_MODE_FAST);
//    APP_ERROR_CHECK(err_code);

	app_uart_close();

// Enter main loop.
for (;;)
{
    power_manage();
}

This result seems to be consistent both if I choose to use EasyDMA or not, i.e. regardless if I choose

#define UART0_CONFIG_USE_EASY_DMA 1

in sdk_config.h or if I choose

#define UART0_CONFIG_USE_EASY_DMA 0