Reduce GPIO current draw

RE: Reduce GPIO current draw

Frikkie Badenhorst — Wed, 11 May 2022 06:15:28 GMT

Cause of issue was that we were using the GPIOTE IN interrupt instead of the PORT interrupt.

RE: Reduce GPIO current draw

Frikkie Badenhorst — Fri, 08 Apr 2022 15:44:00 GMT

Hi Stian,

Thanks for your response. Understood that the using the PORT interrupt will use less current.

Could you please respond with the following on the case which Hung is handling.

1) Is it specified somewhere that the IN event will add current while the PORT event will not?

2) When using the PORT event, and there are 2 inputs on the same GPIO port, how would one know which input triggered the interrupt?

3) How exactly are you measuring current on the DK? Could you please describe your exact hardware setup

Looking forward to your response!

Regards,

Frikkie

RE: Reduce GPIO current draw

Stian Røed Hafskjold — Fri, 08 Apr 2022 15:32:52 GMT

Hi, I realize now that you posted a separate case for the same topic which is handled by Hung. I will follow up there.

RE: Reduce GPIO current draw

Stian Røed Hafskjold — Fri, 08 Apr 2022 15:25:07 GMT

Hi, I would expect to see 50-70 uA with the code you posted. It's using the GPIOTE IN event which will add some additional current. You can use the PORT event instead, which should not add anything to the system on idle current

You use the SENSE bits in the PIN_CNF register to enable GPIO sensing, and then enable the PORT interrupt in the GPIOTE module:

NRF_P0->PIN_CNF[23] = (3 << 2) | (3 << 16); // pin 23, pullup, sense high to low
NRF_GPIOTE->INTENSET = (1 << 31); // enable PORT interrupt

Here is a fully working "bare metal" sample that at least works when using Zephyr. When I run it here I measure about 3 uA. It turns off the LED (pin 28) when the button (pin 23) is pressed.

I see that you are not using Zephyr, but the principle should be the same. Just remove the IRQ_CONNECT macro, and use the GPIOTE0_IRQHandler as you already are doing..

#include <zephyr.h>

void gpiote_irq_handler(void){
    NRF_GPIOTE->EVENTS_PORT = 0; //clear PORT event
    NRF_GPIOTE->INTENSET = 0; // disable PORT interrupt
    NRF_P0->OUTSET = (1 << 28); // Turn off LED
}
void main(void)
{
    IRQ_CONNECT(DT_IRQN(DT_NODELABEL(gpiote)), DT_IRQ(DT_NODELABEL(gpiote), priority), gpiote_irq_handler, NULL, 0); //connect interrupt handler above in zephyr
    irq_enable(DT_IRQN(DT_NODELABEL(gpiote))); //enable GPIOTE interrupts
    NRF_P0->DIRSET = (1 << 28); // LED pin output
    NRF_P0->OUTCLR = (1 << 28); // Turn on LED
    NRF_P0->PIN_CNF[23] = (3 << 2) | (3 << 16); // configure button, pin 23, pullup, sense high to low
    NRF_GPIOTE->INTENSET = (1 << 31); // enable PORT interrupt
    for(;;){
        __WFE();
    }
}

Please try this and see if you get down to normal idle current.

Best regards,
Stian

RE: Reduce GPIO current draw

Sigurd — Fri, 08 Apr 2022 12:37:10 GMT

Hi,

Are you using DCDC mode on app, net, HV regulators?
How is the chip powered?
What voltage is the chip powered at? Are you using VDD or VDDH?
Have you made sure that errata workarounds from the MDK is being enabled and used properly in your OS ?

RE: Reduce GPIO current draw

Frikkie Badenhorst — Tue, 05 Apr 2022 16:30:56 GMT

Hi Sigurd,

Setting ONLY LED1 pin as output keeps the current stable at 11uA. Setting both the LED1 pin and Button1 pin as an output and input respectively, also keeps the current stable at 11uA.

Only after we configure the GPIOTE peripheral to enable the interrupts (as shown in the code of the initial post), the current jumps up into the 270uA range. Its almost as if the device can not go into a low power state while waiting for an interrupt to occur?

Please advise?

RE: Reduce GPIO current draw

Sigurd — Tue, 05 Apr 2022 14:37:58 GMT

Hi,

I would strongly recommend that you use nRF Connect SDK.

[quote user=""]

1) Set LED1 pin as output

2) Set button1 as input and enable the interrupt for it

3) The interrupt service routine then toggles the LED.

[/quote]

Do you see this only when you do all these steps? What if e.g. only set button 1 as input, or only set LED1 as output?