How to get GPIO register state in GPIOTE handler

[Vas]

Hello Nordic! My question probably a simple one but I'm a novice so there's it. I'm looking for a way to get a GPIO port state that was at the moment of GPIOTE event triggering, inside the event handler. Is there any register I can read to get that?

The context: I'm trying to read a two line serial bus of TitanMicro TM1640. The start of transmission is designated by falling DIN line while SCLK line is still high. The time between falling DIN and falling SCLK is about 10 us, so when I'm reading the GPIO from the handler the SCLK is already low.

[Sigurd]

Hi!

A GPIOTE event can come from one of the following input conditions:

• Rising edge
• Falling edge
• Any change

So if you have e.g. configured it to Rising edge, you then already know it was rising to high when the event triggered.

[Vas]

I'm actually looking at the other signal state. I'm catching DIN change by GPIOTE but I need to know if SCLK was high at the moment.

[Sigurd]

Vas said:

I'm catching DIN change by GPIOTE but I need to know if SCLK was high at the moment.

If this SCLK is a input, you could try reading the GPIO IN register. https://docs.nordicsemi.com/bundle/ps_nrf52840/page/gpio.html#ariaid-title7

[Vas]

Will I get the input state of the moment when the GPIOTE event triggered or I'll get the current reading?

[Sigurd]

Current reading. I'm not familiar with TM1640. Is the SCLK input or output from the nRF52840 ?

[Vas]

Both DIN and SCLK are inputs for the nRF52840 in my case. And if that would be the current reading it will be the issue I described in the original post. The time difference between falling DIN and SCLK is 10 us so when I'm reading the GPIO input from the handler it's already past that time and the SCLK is already fallen low.