What is NRF_P0 in the {SDK_PATH}/components/drivers_nrf/hal/nrf_gpio.h

[Daniel T. Lee]

I'm using Keil5 to compile example of SDK v12.2. And I'm trying to understand each of Source code to understand how each of it is consists of.

I opened an example "SDK/Examples/peripheral/blinky/pca10028". (I have nRF51422 DK Board - PCA10028.)

I tried to find "NRF_P0", But can't find any code that defines "NRF_P0". I searched with Keil Studio 5, But there wern't any definition of NRF_P0. (really, I swear there were just code that uses "NRF_P0", and NO Definition!)

I tried to all of the SDK Folder to search "NRF_P0" and there was some files which defines "NRF_P0", But those files aren't related to my board.

The files that defines "NRF_P0" were

Components/device/nrf52.h

Components/device/nrf52840.h

Components/device/nrf51_to_nrf52.h

The first two files were only related to nrf52 boards and I'm using nrf51 board, so I thought those files are not related to my pca10028 board.

And also, nrf51_to_nrf52.h file, I though it just porting file of nrf51 -> nrf52 file.

That gives me an question, where is the definition for NRF_P0 for NRF51 board?

Is the reason that I can't find NRF_P0 Define Line, this NRF_P0 is defined in SoftDevice, So I can't find with it?

(+I'm guessing NRF_P0 means for NRF_GPIO_PIN 0 but i'm not sure it really is.)

[Roger Clark]

Why are you looking for this define for the nRF51 ?

I just opened and compiled that example in Keil and it compiles fine.

If you look at what NRF_PO actually is, you can trace it back to being a pointer to the base of the hardware registers in the nRF52 which control the GPIO.

But I'm still don't understand what problem you actually have

[Daniel T. Lee]

Yeah, It's compiled Really well. But I just want to understand how this source code works, so I tried to find out what NRF_P0 is.

The Thing is, I really can't understand why NRF_P0 points to the hardware register in nRF52 EVEN IF IT'S UPLOADED TO NRF51 Board.

Isn't those two board(NRF51, NRF52 core) is totally diffrent? I thought those two core are totally diffrent so those pinout pointer will be no relationship at all(nRF51, nRF52).

IF those GPIO base pointer location are totally same, It would be located at

Components/device/nrf.h

Not in

Components/device/nrf52.h

Does Nrf51.h file references Nrf52.h file just to get GPIO PIN BASE ADDRESS?

EVEN IF IS JUST UPLOADED TO NRF51 BOARD?

[Roger Clark]

Just because something is defined, it does not mean the code actually use it.

I'm sure there are loads of defines in various headers which the beacon example calls in but never uses.

This is totally normal for C programming.

[Daniel T. Lee]

Thank you for your comment, and i'm not trying to make annoying you,

But I'm really curious about it, and I really want an answer.

---

Yeah, I totally aware of that, but even such example that Really Uses GPIO,

examples/peripheral/gpiote

Even this example does not defines NRF_P0, and I'm pretty sure it refers GPIO Base address, And I guess this example must use NRF_P0.

I still don't understand about this non-define NRF_P0

[Jørgen Holmefjord]

Hi,

In nRF52832, P0 is GPIO PORT 0, which implements pin 0-31. The corresponding port in nRF51x22 is named GPIO, but this is deprecated in nRF52832. If you want to control the GPIO pins directly using registers, without using the GPIO abstraction, you should use NRF_GPIO for accessing the GPIO pins on nRF51x22 devices and NRF_P0 on nRF52832. nRF52840 also implements P1, for the additional GPIO pins (P1.00 - P1.15).

Best regards,

Jørgen