nrf_serial_uninit()

[David Challender]

Hi 

I have a custom board implementation that operates as follows:

1. Monitoring an input pin waiting for low high transition, BLE advertising of device.
2. When input event occurs initialise 2 serial devices and supporting HW to operate as a serial bridge
3. When input pin transitions back to low state uninitialise 2 serial devices and supporting HW to return to Point 1 state

After power on the current in state 1 is 100 micro amps. However after transitioning through 2 and 3 then back to 1 the current settles to 900 micro amps.

I have checked the control of the external devices and have isolated the issue to the initialisation / uninitialisation of the serial devices with either causing the issue.

Wondering if the devices are uninitialising correctly?

        //Configure UARTs using nordic serial service configuration defined in global variables
		ret = nrf_serial_init(&serial0_uart, &m_uart0_drv_config, &serial0_config);
		APP_ERROR_CHECK(ret);
		ret = nrf_serial_init(&serial1_uart, &m_uart1_drv_config, &serial1_config);
		APP_ERROR_CHECK(ret);
		nrf_gpio_pin_clear(U1DTR_PIN);

	
		//Un-initialize UARTs
		ret = nrf_serial_uninit(&serial0_uart);
		APP_ERROR_CHECK(ret);
		ret = nrf_serial_uninit(&serial1_uart);
		APP_ERROR_CHECK(ret);

Using SDK 15 on a nRF52840 with the serial files provided in the attached link:

https://devzone.nordicsemi.com/f/nordic-q-a/25173/nrf52840-uart1-not-working-in-sdk-14/126390#126390

Regards

[Jørgen Holmefjord]

Are you seeing this issue only from initializing/uninitializing the peripheral, or do you do some TX/RX operations in between that could affect the current consumption? If you do TX, have you tried calling nrf_serial_tx_abort before uninit?

[David Challender]

after initialising  the port the serial port is used to transfer data. After the transfer the port is uninitialised and we go to a lower power state. 

I have added  nrf_serial_tx_abort without change  to the current draw after the port is uninitialised. 

[Jørgen Holmefjord]

Do I understand you correctly that if you only initialize an uninitialize the serial library, without any transfers in between, you do not see the increased current issue?

[David Challender]

Yes there is a high current draw without any data transferred. 

[Jørgen Holmefjord]

Please follow the suggestions by Stian Røed Hafskjold in this post. This should fix the issue with high current after uninit.