Combining GPIOTE and high-drive capability

[Boris Matešin]

Hi, I've got a quick question here about using the GPIOTE driver in tandem with the GPIO HAL.

For simplicity's sake, I'm using an in-house library that gives me high-level configuration and usage of GPIOTE pins.
Most of the pins that I use are S0S1 outputs (standard low, standard high) or standard LOTOHI/HITOLO/TOGGLE pins and the lib's worked well so far.

However, every once in a while I need to provide high-drive capability to a pin, in order to actuate a particularly current-hungry relay or other peripheral.
I know the GPIO HAL allows me to set high-drive sinking and sourcing, but I'm not exactly sure how best to apply it to an already GPIOTE-configured pin.

I'm assuming the driver uses the HAL somewhere under the hood - but I still need to know whether I should first configure it with the driver and then apply the HAL drive mode setting, or vice-versa.

Thanks in advance!

[Håkon Alseth]

Hi,

 

The drive strength is set in the GPIO PIN_CNF[my_pin] register, field DRIVE:

https://infocenter.nordicsemi.com/topic/com.nordic.infocenter.nrf52832.ps.v1.1/gpio.html?cp=3_1_0_19_2_9#register.PIN_CNF-0 

Here's an example for setting H0H1 with the help from nrf_gpio.h:

 

nrf_gpio_cfg(
pin_number,
NRF_GPIO_PIN_DIR_OUTPUT,
NRF_GPIO_PIN_INPUT_DISCONNECT,
NRF_GPIO_PIN_NOPULL,
NRF_GPIO_PIN_H0H1,
NRF_GPIO_PIN_NOSENSE);

Set it back to normal S0S1 by calling nrf_gpio_cfg_output.

 

in order to actuate a particularly current-hungry relay or other peripheral.

 You should be very careful with induction loads and driving these directly from a GPIO. You can get high transients directly into the GPIO when pulsing inductive loads, and go outside the maximum ratings of the nRF device, thus permanently damaging the GPIO or chip. Have you considered using a mosfet to drive these loads?

 

Kind regards,

Håkon

[Boris Matešin]

Hi, Håkon,

thanks for linking the referent registers and fields. I remember testing out S0H1 mode at one point in the past, but that was for a very specific use-case (not related to induction loads).

Thanks for the warning about induction loads - I think we'll switch to driving a FET instead of driving the pin directly.

Best regards,

-- Boris