# Disable pin port (NONE option) **URL:** \ **Category:** Uncategorized\ **Created:** [May 15, 2019, 1:24am UTC](https://forum.xod.io/t/disable-pin-port-none-option/2243 "2019-05-15T01:24:39Z")\ **Posts on this page:** 8\ **Page:** 1
**Author:** ![cesars](https://avatars.discourse-cdn.com/v4/letter/c/f05b48/32.png) [@cesars](https://forum.xod.io/u/cesars)\ **Post date:** [May 15, 2019, 1:24am UTC](https://forum.xod.io/t/disable-pin-port-none-option/2243/1 "2019-05-15T01:24:39Z")
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. ---
**Author:** ![nkrkv](https://yyz1.discourse-cdn.com/flex027/user_avatar/forum.xod.io/nkrkv/32/8_2.png) [@nkrkv](https://forum.xod.io/u/nkrkv)\ **Post date:** [May 15, 2019, 3:54pm UTC](https://forum.xod.io/t/disable-pin-port-none-option/2243/2 "2019-05-15T15:54:32Z")
Nulls are a [billion dollar mistake](https://medium.com/@hinchman_amanda/null-pointer-references-the-billion-dollar-mistake-1e616534d485) 🙂 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. ---
**Author:** ![cesars](https://avatars.discourse-cdn.com/v4/letter/c/f05b48/32.png) [@cesars](https://forum.xod.io/u/cesars)\ **Post date:** [May 15, 2019, 4:17pm UTC](https://forum.xod.io/t/disable-pin-port-none-option/2243/3 "2019-05-15T16:17:34Z")
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. ![image](https://canada1.discourse-cdn.com/flex027/uploads/xod/original/2X/4/462b0ced8040390f99b6329c9f4e797a6f4776f6.png) 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 ---
**Author:** ![nkrkv](https://yyz1.discourse-cdn.com/flex027/user_avatar/forum.xod.io/nkrkv/32/8_2.png) [@nkrkv](https://forum.xod.io/u/nkrkv)\ **Post date:** [May 15, 2019, 4:33pm UTC](https://forum.xod.io/t/disable-pin-port-none-option/2243/4 "2019-05-15T16:33:39Z")
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++: ```cpp uint8_t x = 255; int8_t y = -1; assert(x == y); // true, passes ``` ---
**Author:** ![cesars](https://avatars.discourse-cdn.com/v4/letter/c/f05b48/32.png) [@cesars](https://forum.xod.io/u/cesars)\ **Post date:** [May 15, 2019, 4:38pm UTC](https://forum.xod.io/t/disable-pin-port-none-option/2243/5 "2019-05-15T16:38:17Z")
> [@nkrkv](#): > > uint8\_t x = 255; int8\_t y = -1; assert(x == y); // true, passes Ok, I understand better This library has the RESET and EOC pins, but they are not always used. > **[Adafruit MPRLS Ported Pressure Sensor Breakout - 0 to 25 PSI](https://www.adafruit.com/product/3965)** > > We stock a few barometric pressure sensors, great for altitude and weather measurements. This pressure sensor is special because it comes with a metal port! Unlike other pressure sensors, ... 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. ---
**Author:** ![nkrkv](https://yyz1.discourse-cdn.com/flex027/user_avatar/forum.xod.io/nkrkv/32/8_2.png) [@nkrkv](https://forum.xod.io/u/nkrkv)\ **Post date:** [May 15, 2019, 4:44pm UTC](https://forum.xod.io/t/disable-pin-port-none-option/2243/6 "2019-05-15T16:44:56Z")
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! ❤ ---
**Author:** ![cesars](https://avatars.discourse-cdn.com/v4/letter/c/f05b48/32.png) [@cesars](https://forum.xod.io/u/cesars)\ **Post date:** [May 15, 2019, 9:38pm UTC](https://forum.xod.io/t/disable-pin-port-none-option/2243/7 "2019-05-15T21:38:22Z")
> [@nkrkv](#): > > If it will be convenient we can consider adding a similar not-a-pin literal to XOD. for having a fixed idea or for reading fast I missed this, sorry. 🤦‍♂️ ---
**Author:** ![system](https://canada1.discourse-cdn.com/flex027/uploads/xod/original/1X/eb7348baa04192c2ef932d1db54d44f09f8a7888.png) [@system](https://forum.xod.io/u/system)\ **Post date:** [May 17, 2019, 9:38pm UTC](https://forum.xod.io/t/disable-pin-port-none-option/2243/8 "2019-05-17T21:38:25Z")
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