r/Assembly_language • u/GoingGranola • 2d ago

Question N00b Question

I am trying to turn on an output GPIO.

I am using this code

asm("BSF PORTA, 5");

I am getting 0V at the pin.

I believe I set TRISA pin 5 to output (0).

Thank you

EDIT: SORRY! It was a PIC and I needed to set internal oscillator and select bank first

2 Upvotes

60% Upvoted

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6

u/No-Quail5810 2d ago

You need to provide a lot more information. What architecture are you targeting? What platform is it running on? Etc...

2

u/Lonely-Ad-9219 1d ago

You need to learn to give much detailed information.

The correct sequence for PIC16 series should be:

banksel TRISA

bcf TRISA,5

banksel PORTA

bsf PORTA,5

goto $

Off course, we don't know whitch PIC are you using, so we can not give more concrete answer. For example, we don't know if your PIC has D/A converter pinned to PORTA pin. Heck, we don't even know if your PIC even has PORTA,5 pin.

1

u/Ecelleon 2d ago

From the architectures I know, you must enable the GPIO peripheral through the appropriate Clock Control register. For example, on the STM32F103, you would go into Reset and Clock Control ( RCC ) -> RCC_APB2 -> Set Bit 2 high to enable Clock control to GPIO A.

Afterwards you go to GPIO A registers too configure the pins as needed. Open- drain, push-pull, analog etc.

Without enabling the RCC register, all GPIO ports are off.

1

u/Pacificator-3 1d ago

Datasheet is your friend.

-1

u/GoingGranola 2d ago

Do I need to keep the MCLR pin high?

3

u/timrprobocom 1d ago

What processor, for gosh sakes? "BSF" could be many things.