How to disconnect the input buffer?

RE: How to disconnect the input buffer?

nordev — Thu, 08 Oct 2020 21:16:10 GMT

Thanks Vidar!

EDIT: found the answer explaining drive strength in this forum post here

Please tell me if I am wrong, but it seems like nrf_gpio_cfg() just changes what setting 1 or 0 means, and the actual strength (0 or 1) has to be configured with some other function.

If this is correct, how do I actually set the drive strength to 0 or 1?

RE: How to disconnect the input buffer?

Vidar Berg — Thu, 08 Oct 2020 06:29:16 GMT

I'm not familiar with how it works internally, but it is fine to leave the input floating when the input buffer is disconnected. It will not lead to any leakage current.

The drive strength is configured in the same register I linked to earlier. It can be set directly or through the nrf_gpio_cfg() call.

RE: How to disconnect the input buffer?

nordev — Wed, 07 Oct 2020 19:05:01 GMT

Thank you Vidar - very helpful.

When the input buffer is disconnected, is anything done internally to keep the CMOS from floating & turning both FETs on simultaneously?

Also, how do you configure drive strength?

RE: How to disconnect the input buffer?

Vidar Berg — Wed, 07 Oct 2020 09:14:17 GMT

Hello,

GPIOs are configured as inputs with the input buffer disconnected on reset as can be seen from the screenshot below. This means you can skip configuration of unused pins in your app. You can also use the nrf_gpio_cfg_default() function if you need to configure a pin back to its reset state.

(Link to PIN_CNF[n])