Issue with setting GPIO pins as output.

[gojiman23]

Hello, I am new to developing with nrf and have been trying to follow tutorials on individually setting pins as output. I am working on just getting a specified pin to blink an LED.

My code is as follows:

#define PIN27 27

int main(void)
{
    nrf_gpio_cfg_output(PIN27);
    nrf_gpio_pin_clear(PIN27);
    while(1)
    {
        nrf_gpio_pin_toggle(PIN27);
        nrf_delay_ms(1000);
    }
}

For some reason, the LED is not blinking even though it seems I've followed the code online perfectly. Can anyone see the issue?

[johnny]

This look like correct

what is your hardware design?

maybe your pin use pin27 not P0.27

[gojiman23]

I'm using the nrf52840PDK. what is the difference between pin27 and P0.27?

[gojiman23]

Sorry, I meant an external LED*

[awneil]

So if you disconnect this "external LED" - is the pin toggling OK ?

If you connect this "external LED" - to  pin 16, does it work?

[gojiman23]

No, the led doesn't work when connected to pin 16. I just used a wire to connect to an LED on a breadboard. I am pretty new to embedded systems in general so is there a better way to test if the pin toggling is working?

[haakonsh]

Yeah, an oscilloscope or digital analyzer. 

Most likely you've not wired the LED circuit correctly.

[awneil]

gojiman23 said:

the led doesn't work when connected to pin 16

So that means the problem is not (just) down to your code - doesn't it?

There must be something else (also) wrong with your LED and/or the way you are connecting.

gojiman23 said:

I just used a wire to connect to an LED on a breadboard.

You need to give more details!

preferably, a full schematic (aka "circuit diagram")

some good, clear, in-focus photos could also help.

gojiman23 said:

I am pretty new to embedded systems in general

Do you have experience with basic electronics?

Here's some good beginner stuff on LEDs: https://electronicsclub.info/leds.htm

And some stuff on connecting LEDs to chips: https://electronicsclub.info/ics.htm

gojiman23 said:

is there a better way to test if the pin toggling is working

As haakonsh says, an oscilloscope is the key tool.

You should be able to see that a pin is slowly toggling between high & low using a voltmeter - but a meter cannot show you if anything high-speed is happening.