ncs1.61 peripheral_uart : enable uart when connected and disable uart when disconnected

[RHeine]

Hi,

I work with win10 laptop, Toolchain  nrf Connect SDK 1.6.1 on a nrf5340dk.

On peripheral_uart sample, I would like to enable uart when a device is connected and I want to disable uart when device is disconnected to reduce consumption.

There is the consumption mesure by PPK2:

It's seem that between two advertisings the consumption is due to the enable uart.

I need to have the lowest consumption when the nrf5340dk is advertising.

First step, I tryed to disable uart from prj.conf:

CONFIG_SERIAL=n & CONFIG_LOG=n

but after build and download the 4 led were ON and the was no more advertising.

Second step, I tryed to disable uart from the overlay file:

&uart0 {
    status = "disable";

};

but after build and download there was no led on and no more advertising.

There is my project:

5040.peripheral_uart.zip

Could you give me, please,  an example how to enable uart when a device is connected and disable uart when device is disconnected ?

Best regards,

Rob.

[Kazi Afroza Sultana]

Hello Robert,

You can use the low-power UART driver implementation if you want to wake up on UART and keep the current consumption low.  

The protocol used by this driver implements two control lines ( the Request line (REQ) and the ready line (RDY) to allow disable the UART during the idle period Low power UART driver — nRF Connect SDK 1.7.99 documentation (nordicsemi.com). So it requires extra flow control pins on the UART besides Rx-pin and Tx-pin. So, the device tree should look like this

&uart1{

         compatible = "nordic, nrf-urate";

         status = "okay";

         rx-pin =<44>;

         tx-pin = <45>;

         baudrate =<1000000>;

 lpuart: nrf-sw-lpuart {   // this part is the child node of the UART instance that extends standard UART configuration with the control lines REQ and RDY 

           compatible = "nordic, nrf-sw-lpuart";

           status = "okay";

           label   = "LPUART";

          req-pin =<46>;

          rdy-pin = <47>;

};

};

Apart from this, here is a sample of turning off and on the UART during run-time: https://github.com/nrfconnect/sdk-zephyr/tree/main/samples/boards/nrf/system_off

Best Regards,

Kazi Afroza Sultana

[RHeine]

Why do you send me the same answer ?

[Kazi Afroza Sultana]

Internet connection was going online and offline simultaneously. It shows my replies did not send so I pressed reply 2 times. and you got the 2 same replies. 

[RHeine]

Hi Kazi,

I found the error, I wrote "pm_device_state_set(uart, PM_STATE_ACTIVE, NULL, NULL);"

instead of "pm_device_state_set(uart, PM_DEVICE_STATE_ACTIVE, NULL, NULL);"

Now it's working.

Regards,

Rob.

[Kazi Afroza Sultana]

Hello Robert,

That's nice to hear. Both of the issues (Advertising and off and on UART during Runtime) are solved. 

Best Regards,

Kazi Afroza Sultana