Is it possible to save the 1µA idle current for UARTE?

[Joe]

When I call APP_UART_FIFO_INIT(), receive and transmit some data, then call app_uart_close(), I have 3.7µA sleep current. If I don't call the uart init and close function, my sleep current is 2.1µA. I have an external interrupt to wake up and enable the UART, I don't need the UART at all during sleep. Is it possible to save the 1.6µA?

I search old posts and saw the suggestions, they didn't help. I tried the following after app_uart_close()

1. NRF_UART0->ENABLE = 0;

2. Configure TXD pin output high, RXD pin input with pullup enabled

3. *(volatile uint32_t *)0x40002FFC = 0;

  *(volatile uint32_t *)0x40002FFC;

  *(volatile uint32_t *)0x40002FFC = 1;

I use SDK15.0, Rigado BMD300 module.

Thanks.

[hmolesworth]

Maybe break after the app_uart_close() and check the tx, rx, rts and cts pin settings; they are supposed to be released and disconnected by that function, but it's worth checking ..