Best nRF9160 Zephyr way to configure high impedance pin state?

RE: Best nRF9160 Zephyr way to configure high impedance pin state?

tedhavelka — Fri, 08 Apr 2022 14:57:13 GMT

Hello Øyvind,

With my question I meant to ask whether in Zephyr 2.6.0 GPIO framework, need I a different pin configuration for pins which in normal, active powered mode are inputs, versus other pins which are outputs. I am sorry for the poorly worded question!

I will re-run a couple tests using GPIO_DISCONNECTED. I recently discovered that symbol in Zephyr documentation, but when I apply it to just a few pins (which were not explicitly configured yet) I see current increase, not decrease. If the pin configuration GPIO_DISCONNECTED is physically disconnecting the I/O pins of the nRF9160, I would expect overall board current to remain the same or decrease. My observations however are counter-intuitive.

There are a couple of tests I will set up and observe. But it sounds like for both "active time" input and output lines to the nRF9160, the highest impedance setting is GPIO_DISCONNECTED, correct?

One more question: is it a valid design choice to call Zephyr RTOS gpio configuration API periodically during firmware run time? In other words, when electrically safe does the nRF9160 support Zephyr or other code changing GPIO configuration dynamically?

- Ted

RE: Best nRF9160 Zephyr way to configure high impedance pin state?

Øyvind — Fri, 08 Apr 2022 12:50:29 GMT

Hello Ted,

I'm not quite sure what you are asking for. Do you need pin configuration for three different scenarios?

[quote user=""]It has this form, but I find that _FLAGS by default gets assigned a value of zero:[/quote]

Yes, this seems correct base don the response of the DT_GPIO_FLAGS API

In regards to setting the pin to high-impedance, the following call should be used:

gpio_pin_configure(led.port, led.pin, GPIO_DISCONNECTED);

Kind regards,
Øyvind

RE: Best nRF9160 Zephyr way to configure high impedance pin state?

tedhavelka — Thu, 07 Apr 2022 19:08:27 GMT

For some reason the Zephyr documentation link I entered in my initial post is incorrect, broken. The correct link is:

https://docs.zephyrproject.org/2.6.0/reference/peripherals/gpio.html?highlight=gpio_disconnected#c.GPIO_DISCONNECTED