UART Enable/Disable with sdk v1.3.0

RE: UART Enable/Disable with sdk v1.3.0

Lamdev — Tue, 16 May 2023 13:06:50 GMT

Hello Tjaz

At which level did you succeed to reduce the power consumption ?

Do you have code sample for your UART shutdown ?

Best regards,

Lam

RE: UART Enable/Disable with sdk v1.3.0

Tjaz — Wed, 15 Jul 2020 08:30:11 GMT

Hello again,

sorry.

We use uart0 and uart1 (one for debug, and one to communicate with another chip). I was testing by enabling/disabling only uart1, but turns out, if I disable both, power consumption drops as expected.

Sorry for the trouble.

For others looking at this thread, both methods work (using the new power management api and using the registers directly).

Regards,
Tjaž

RE: UART Enable/Disable with sdk v1.3.0

Tjaz — Wed, 15 Jul 2020 07:51:04 GMT

Hello,

I have tried both GPIO_INPUT and GPIO_DISCONNECTED insted of GPIO_OUTPUT:

gpio_pin_configure(gpio_dev, PIN_UART_0_RX, GPIO_DISCONNECTED);
gpio_pin_configure(gpio_dev, PIN_UART_0_TX, GPIO_DISCONNECTED);

and

gpio_pin_configure(gpio_dev, PIN_UART_0_RX, GPIO_INPUT);
gpio_pin_configure(gpio_dev, PIN_UART_0_TX, GPIO_INPUT);

Both have the same effect on power consumption as GPIO_OUTPUT - none.

Again, to reiterate:
The code I posted used to work for us, and we saw power consumption drop, this means that the UART peripheral device did in fact "shut down" and get cut from power.

Now, with sdk v1.3.0, this no longer happens.

Even if setting the pins to output causes the nRF to "use power to keep it low" as you stated, the power consumption should still change (drop), since the UART device should be disabled.

RE: UART Enable/Disable with sdk v1.3.0

Edvin — Tue, 14 Jul 2020 14:11:46 GMT

Hello Tjaž,

For lowest current consumption, the pins should be set to disconnected input. Can you please try to set this in the uart_0_disable() function?

when you set it to output, the nRF will use power to keep the pin low. Especially if there is something else in the other end trying to pull it high.

Best regards,

Edvin