digitalWrite

Forum 2005-2010 (read only) Software Development
1

I've been trying to use the Void of digitalWrite without really typing digitalWrite, so I looked inside the wiring_digital.c file and I saw how the digitalWrite is made.

the first line is

uint8_t timer = digitalPinToTimer(pin);

and in the pins_arduino.h i found this line

#define digitalPinToTimer(P) ( pgm_read_byte( digital_pin_to_timer_PGM + (P) ) )

and this line

extern const uint8_t PROGMEM digital_pin_to_timer_PGM[];

so basically all i have in my arduino program is this :

extern const uint8_t PROGMEM digital_pin_to_timer_PGM[];

#define digitalPinToTimer(P) ( pgm_read_byte( digital_pin_to_timer_PGM + (P) ) )

void setup() 
{
  
}
void loop() 
{
uint8_t timer = digitalPinToTimer(1);
}

but I'm stuck, whenever I try to compile I get the error message: " error: expected initializer before 'digital_pin_to_timer_PGM' "

anyone knows what can cause this? and how do I solve it?

Thanks very much.

2

anyone knows what can cause this? and how do I solve it?

Yes and yes.

But first, why are you doing this?

3

It will sound crazy.
I'm trying to write my own langage for the AVR assembly commands, my own version of arduino.

4

It will sound crazy.

I was already thinking that. :wink:

I'm trying to write my own langage for the AVR assembly commands, my own version of arduino.

Crazy and ambitious. I hope you're successful (not because I dislike the Arduino but because I'm extremely curious about your plan).

Add this to the top of your Sketch...

#include <avr\pgmspace.h>
5

If you are doing this to make improvements then you would be better off finding a different way to do the pin number translation.

For example, have a look at the way its done by teensyduino, see pins_teensy.c after getting the download from : Teensyduino - Add-on for Arduino IDE to use Teensy USB development board

6

Thanks guys for supporting :slight_smile:

mem - why would I want to find a different way to translate the pins of atmega? whats wrong with the original way?

7

whats wrong with the original way?

That was the question I was going to ask you :wink:

I guess I don't understand what you want to do an why you want to do it.

perhaps you can you clarify

8

Well, it could be a good way of teaching myself how the arduino language is made.
I dont have an intention of changing the pins_arduino.c because there are no commands there, only definition of each pin (right?)

9

Yes, pins_arduino.c contains information on the mapping of pins to physical ports and timers. This information is stored in program memory to minimse the RAM usage.

wiring_digital.c and wiring_analog.c contain the commands that use this information to do something with the pins.

studying those three files should help you see how arduino uses pins