app_uart high sleep current issue

[John]

Hi, 

We are making software for our custom board based on nRF52833 and nRF5 SDK 17.0.2. We use app_uart for our serial communication in active mode and in sleep mode we disable the UART. Without APP_UART_FIFO_INIT the device's current consumption is about 2uA in sleep mode using nrf_pwr_mgmt_run(). When we initialize UART for serial communication, we have made sure to uninitilaze UART by calling app_uart_close function and set UART TX and UART RX pin to  INPUT_NOPULL before setting the device to sleep mode, but current that does not work. The sleep current consumption is now about 179uA. Here is our configurations for app_uart

//brief: uart settings:

static app_uart_comm_params_t comm_params = {

    .rx_pin_no    = UART_RX,

    .tx_pin_no    = UART_TX,

    .rts_pin_no   = 0xffffffff,

    .cts_pin_no   = 0xffffffff,

    .flow_control = APP_UART_FLOW_CONTROL_DISABLED,

    .use_parity   = false,

#if defined (UART_PRESENT)

    .baud_rate    = NRF_UART_BAUDRATE_115200

#else

    .baud_rate    = NRF_UARTE_BAUDRATE_115200

#endif

};

APP_UART_FIFO_INIT(&comm_params,

                       DRV_UART_RX_BUFFER_SIZE,

                       DRV_UART_TX_BUFFER_SIZE,

                       uart_callback_handle,

                       APP_IRQ_PRIORITY_LOWEST,

                       err_code);

[John]

Allright! I finally found the root cause for high sleep current consumption in my device. It was not the issue with app_uart_close nor the issue with the nRF52833 SoC. So using just  app_uart_close() is the proper setup before going to sleep. So we can close the topic here. Thank you so much for you help!