Quick question about port variable name settting

Getting Started
1

I’ve thought about this for a long time and mostly just gone on with it, until today when it began to nag at me for an answer…

int port1 = D0;
pinMode(port1, OUTPUT);
etc…

why do we set the type to int when D0 doesn’t seem to be an int?

2

Because they are int’s? :wink:
If you check out the source code, you can see them defined just here:

The compiler will convert the 0, 1, 2 (and so on) to int’s when the firmware is built.

1 Like
3

It’s a good question. The prototype for pinMode, digitalWrite, etc. specifies it as a uint16_t.

I always assumed storing it in an int was an Arduino thing, but it’s uint8_t in the real Arduino.h.

But it kind of doesn’t matter as all uint16_t values fit in an int, and uint16_t values are padded out to 4 bytes (except in arrays and two adjacent 16-bit quantities in a struct) on the STM32 so both use the same amount of RAM or stack as an int.

1 Like
4

Thanks!

Great answers, I figured it was something like that, but didn’t know where to look!

I’ll be able to sleep tonight…

David G.