Raw GPIO output without using API Functions?

RE: Raw GPIO output without using API Functions?

awneil — Tue, 02 Jul 2019 20:34:56 GMT

you might want some 'volatile' qualifiers in there ...

RE: Raw GPIO output without using API Functions?

jwhitmore — Tue, 02 Jul 2019 19:03:42 GMT

I found the source of problem if not the solution. The code I posted might not be agreeable to people's taste but it does actually function as intended when compiled and linked with gcc compiler. However if you compile it in a main.cc with the g++ compiler whilst it does compile and link the code does not function as intended. So down to my toolchain.

RE: Raw GPIO output without using API Functions?

jwhitmore — Mon, 01 Jul 2019 20:13:43 GMT

The purpose of this piece of code is to verify the build process and flashing of the target device. As soon as those stages have been verified the code will be dumped. So I'm not really going for human readable here. I want the compiler to be able to read it and the uC to be able to execute the resulting output hex file.

Since nobody has pointed out any errors in the code, apart from no being to their individual taste and style I'll assume that the code's functionality is correct and the problem lies elsewhere.

RE: Raw GPIO output without using API Functions?

haakonsh — Mon, 01 Jul 2019 13:10:56 GMT

I suggest you use the definitions of the HAL, you do not need to use any functions, but at least you code will be human-readable.

RE: Raw GPIO output without using API Functions?

RK — Sun, 30 Jun 2019 23:09:16 GMT

you might want to say which of the many chips and development boards you're using, I'm guessing the nRF52836 dev board but it could be anything.

The declarations come in very handy when you switch from one chip to another. As long as the peripheral has the same behavior you don't have to go edit all your code. I have stuff I wrote for the old nRF51 series and still use now. Those struct/entry type definitions for peripherals are followed by just about every manufacturer of anything using ARM, and it's certainly not frowned upon to use them.

RE: Raw GPIO output without using API Functions?

jwhitmore — Sun, 30 Jun 2019 19:46:50 GMT

Is it not working because of the Magic numbers? That's impressive silicone!

I'll try replacing the numbers with const declarations and see how it works out.. I'll let you know.

RE: Raw GPIO output without using API Functions?

Turbo J — Sat, 29 Jun 2019 21:15:02 GMT

Waaay too many magic numbers.

Directly manipluating reisters should lookr like this:

int PIN_NR= 3; // or use a define

NRF_GPIO->PIN_CNF[PIN_NR] = 
    (NRF_GPIO_PIN_DIR_OUTPUT << GPIO_PIN_CNF_DIR_Pos) 
  | (NRF_GPIO_PIN_S0S1 << GPIO_PIN_CNF_DRIVE_Pos) ;
  
 NRF_GPIO->DIRSET = (1<< PIN_NR);
 NRF_GPIO->OUTSET = (1<< PIN_NR);

Note that on the bigger NRF52840 you'll need to use NRF_P0 and NRF_P1 for the GPIO Ports.