arduino / arduino/ArduinoCore-megaavr

Warning when second argument in digitalWrite is not PinStatus

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core-api
Dominant language
C++
Stars
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Forks
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Description

It seems like the second argument of digitalWrite is expecting a constant from `PinStatus`. However this isn't always ideal, and we get an ugly warning like shown below when this is not the case.

```
/var/folders/6l/ypg6qbw172v1s4vtt6g990tw0000gn/T/arduino_modified_sketch_206750/BlinkWithoutDelay.ino: In function 'void loop()':
/var/folders/6l/ypg6qbw172v1s4vtt6g990tw0000gn/T/arduino_modified_sketch_206750/BlinkWithoutDelay.ino:69:34: warning: invalid conversion from 'int' to 'PinStatus' [-fpermissive]
digitalWrite(ledPin, ledState);
^
In file included from /Users/hans/Documents/Arduino/hardware/MegaCoreX/avr/cores/coreX-corefiles/api/ArduinoAPI.h:52:0,
from /Users/hans/Documents/Arduino/hardware/MegaCoreX/avr/cores/coreX-corefiles/Arduino.h:23,
from /var/folders/6l/ypg6qbw172v1s4vtt6g990tw0000gn/T/arduino_build_868899/sketch/BlinkWithoutDelay.ino.cpp:1:
/Users/hans/Documents/Arduino/hardware/MegaCoreX/avr/cores/coreX-corefiles/api/Common.h:104:6: note: initializing argument 2 of 'void digitalWrite(pin_size_t, PinStatus)'
void digitalWrite(pin_size_t pinNumber, PinStatus status);
^
```

``` c
// Blink without Delay

// constants won't change. Used here to set a pin number:
const int ledPin = LED_BUILTIN;// the number of the LED pin

// Variables will change:
int ledState = LOW; // ledState used to set the LED

// Generally, you should use "unsigned long" for variables that hold time
// The value will quickly become too large for an int to store
unsigned long previousMillis = 0; // will store last time LED was updated

// constants won't change:
const long interval = 1000; // interval at which to blink (milliseconds)

void setup() {
// set the digital pin as output:
pinMode(ledPin, OUTPUT);
}

void loop() {
// here is where you'd put code that needs to be running all the time.

// check to see if it's time to blink the LED; that is, if the difference
// between the current time and last time you blinked the LED is bigger than
// the interval at which you want to blink the LED.
unsigned long currentMillis = millis();

if (currentMillis - previousMillis >= interval) {
// save the last time you blinked the LED
previousMillis = currentMillis;

// if the LED is off turn it on and vice-versa:
if (ledState == LOW) {
ledState = HIGH;
} else {
ledState = LOW;
}

// set the LED with the ledState of the variable:
digitalWrite(ledPin, ledState);
}
}
```

Contributor guide

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Research direction

Reproduce the warning with the included BlinkWithoutDelay sketch, then inspect the digitalWrite declaration in Common.h and how ArduinoAPI.h exposes it. Compare the expected PinStatus argument with the example's int ledState; done means the reported valid usage no longer produces this conversion warning.

Written by the indexing model from the issue text.

Assessment

Tech stack
cpp
Domain
embedded-iot
Issue type
Bug
Difficulty
3/5
Estimated time
1-2 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
35/100

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