Pin not "writable" after tone()

[fabianoriccardi]

Basic Infos

• [ X] This issue complies with the issue POLICY doc.
• [ X] I have read the documentation at readthedocs and the issue is not addressed there.
• [X ] I have tested that the issue is present in current master branch (aka latest git).
• [ X] I have searched the issue tracker for a similar issue.
• [X ] If there is a stack dump, I have decoded it.
• [ X] I have filled out all fields below.

Platform

• Hardware: ESP-01
• Core Version: 8ae0746
• Development Env: Arduino IDE
• Operating System: Windows

Settings in IDE

• Module: Wemos D1 mini v3.0.0
• Flash Mode: dio
• Flash Size: 4MB
• lwip Variant: v2 Lower Memory
• Reset Method: ?
• Flash Frequency: 40Mhz
• CPU Frequency: 80Mhz
• Upload Using: SERIAL
• Upload Speed: 921600

Problem Description

I'm using tone(..) function to play some melodies on a passive buzzer (this is my breakout: https://robotdyn.com/buzzer-module.html). After the melody, I should standby the buzzer to save energy, so I have to write 1 on the digital pin. I observed that after the tone function is impossible to command that pin, it stays low. The problem is not hardware, since this behaviour is observable even without a buzzer...

MCVE Sketch

#include <Arduino.h>

void setup() {
  pinMode(D6,OUTPUT);
  digitalWrite(D6, HIGH);  // the pin really goes HIGH
  delay(5000);

  tone(D6,1000,500);
  delay(1500);
  noTone(D6);   // This makes no difference, I was thinking it is necessary to "release" the pin...
  
  pinMode(D6,OUTPUT);
  digitalWrite(D6, HIGH);  // It stays low
}

void loop() {

}

[liebman]

I can confirm this. I modified the sketch to add a second pin to trigger a scope. The pin actually does go high but is then driven low less than 1ms later, I've seen 100us to 750us. I also tried adding a delay after noTone() to see if it was some delayed interrupt/timer but that made no difference.

#include <Arduino.h>

void setup() {
    pinMode(D5, OUTPUT);
    digitalWrite(D5, LOW); // Second scope channel used as trigger

    pinMode(D6,OUTPUT);
    digitalWrite(D6, HIGH);  // the pin really goes HIGH
    delay(5000);

    tone(D6,1000,500);
    delay(1500);
    noTone(D6);   // This makes no difference, I was thinking it is necessary to "release" the pin...

    delay(1500);
    
    pinMode(D6,OUTPUT);
    digitalWrite(D5, HIGH);  // trigger scope
    digitalWrite(D6, HIGH);  // pulses high and is changed low again after 750us
}

void loop() {

}

[earlephilhower]

Thanks for the clear MCVE. The ISR was disabling the pin and writing 0 every time it was called, even if it was already disabled. Check the PR if you can, but I've verified it on my own logic analyzer.

[fabianoriccardi]

Yeah the fix works for me, thanks!

I'm new with this procedure (pull request, complex versioning and so on...) but I would ask if this fix will be included in version 2.5.

[devyte]

PR is merged.