Disable pin port (NONE option)

#1

In an X library, there are pins that can be used or maybe not.

Is there any way to disable the use of the pin?
for example if instead of using input-port I use input-number and I set a value -1. But I’m not sure if it’s the best.
Maybe the port pin should have a NONE option.

#2

Nulls are a billion dollar mistake :slight_smile: XOD don’t want to repeat it.

In the particular case you describe, you can try using D255 as a special value which means nothing. Arduino defines a NOT_A_PIN macro in C++ which is 255 behind the scenes. If it will be convenient we can consider adding a similar not-a-pin literal to XOD.

#3

the concrete example is a library that has a CS pin, a ENABLE pin and an INT.
Sometimes it is not necessary to use them, because the program does not require it, and it leaves me pins that I can not use. I thought that a none would put a -1, and so could avoid losing a pin.

Here is another example, the EN pin sometimes does not need to be used, but it removes an arduino pin.

ps: In an arduino library I saw that it uses -1 to not define that pin and thus leave it free for another use.

If instead of using input-port I use input-number I solve the problem. But I found that NONE = -1 better in input-port, I do not know if it would be possible

#4

I see. D255 gets converted to uint8_t equal to 255 in C++ and if a function takes int8_t or uint8_t as an argument, 255 and -1 are the same values.

In other words, in C++:

uint8_t x = 255;
int8_t y = -1;
assert(x == y); // true, passes
#5

Ok, I understand better
This library has the RESET and EOC pins, but they are not always used.

If I make a library, I would like to be able to decide if those pins were used or not in the patch, without having to edit it or make another node without the pin.

#6

Yes, in this case, you can make a node which has EOC and RST port inputs. Bind the D255 value to them by default. The D255 will mean “not used”. It will be indistinguishable from -1 for the Adafruit’s C++ library.

P.S> Thanks for trying to help with the sensor breakout node! :heart:

1 Like
#7

for having a fixed idea or for reading fast I missed this, sorry. :man_facepalming:

closed #8

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