`pinMode` disables interrupts as a side effect

[quentinmit]

Board

ESP32-DevKitC

Device Description

DevKitC

Hardware Configuration

For the demo code below, connect a switch or square wave to pin 19.

Version

v2.0.2

IDE Name

PlatformIO

Operating System

macOS

Flash frequency

40MHz

PSRAM enabled

no

Upload speed

115200

Description

The pinMode call, in addition to changing pullups/whether a pin is driving the output or not/etc, appears to disable pin interrupts as a side effect. In the ESP-IDF version of the code, intr_type is explicitly set to GPIO_INTR_DISABLE. In the older register code, the field is accidentally overwritten by the write to GPIO.pin[x].val when it's really just trying to set GPIO.pin[x].pad_driver.

This is a problem because while pinMode is IRAM_ATTR and safe to call from interrupt handlers, attachInterrupt is not (and it's also rather heavyweight), so it's not possible to re-enable the interrupt if pinMode is being used in an ISR.

pinMode should just preserve whatever previous state of interrupts existed; if the user has an interrupt configured on a pin and wants to change the pin mode, they probably know what they are doing. If they want to disable the interrupt they can call detachInterrupt directly.

Sketch

#include "Arduino.h"

// This sketch should print the number of times pin 19 changes.

uint32_t interrupt_count = 0;

void IRAM_ATTR pin_interrupt(void *arg) {
  interrupt_count++;
  pinMode(19, INPUT);
}

void setup() {
  pinMode(19, INPUT);
  attachInterruptArg(19, pin_interrupt, 0, CHANGE);
}

void loop() {
  ESP_LOGD("loop", "interrupt count %d", interrupt_count);
  delay(500);
}

Debug Message

n/a

Other Steps to Reproduce

No response

I have checked existing issues, online documentation and the Troubleshooting Guide

• I confirm I have checked existing issues, online documentation and Troubleshooting guide.

[SuGlider]

Issue confirmed with the latest Arduino Core Version 2.0.3-RC1.

@P-R-O-C-H-Y, PTAL

[TD-er]

Hmm I think this also affects PWM.
Set PWM on a pin and call pinMode => No more active PWM on that pin.

[P-R-O-C-H-Y]

Hi @quentinmit
When calling pinMode(pin,mode); it configures the pin for default config, which is interrupt disabled.
So you need to call attachInterruptArg(19, pin_interrupt, 0, CHANGE); again after pinMode to make it work :)

#include "Arduino.h"

// This sketch should print the number of times pin 19 changes.

uint32_t interrupt_count = 0;

void IRAM_ATTR pin_interrupt(void *arg) {
  interrupt_count++;
  pinMode(19, INPUT);
  attachInterruptArg(19, pin_interrupt, 0, CHANGE);
}

void setup() {
  pinMode(19, INPUT);
  attachInterruptArg(19, pin_interrupt, 0, CHANGE);
}

void loop() {
  ESP_LOGD("loop", "interrupt count %d", interrupt_count);
  delay(500);
}

[P-R-O-C-H-Y]

Hi @TD-er,

If you setup some PWM peripheral like LEDC on a pin, when you call pinMode on same pin, the configuration will set the pin function to be GPIO and the signal from peripheral will be no longer connected to the pin.

[TD-er]

Hi @TD-er,

If you setup some PWM peripheral like LEDC on a pin, when you call pinMode on same pin, the configuration will set the pin function to be GPIO and the signal from peripheral will be no longer connected to the pin.

Yep, found that too, after updating to IDF4.4
With the older SDK it behaved differently.