Only seeing rising-edge interrupts.

[pbaughman]

Hello! I've got some code that I'm porting to the Arduino Nano BLE. I'm having some difficulty because I think I'm only seeing rising edges in my interrupt handler instead of rising and falling edges. The following code minimally reproduces the issue:

#define TEST_PIN 3

void setup() {
  Serial.begin(9600); // open the serial port at 9600 bps for debugging
  pinMode(TEST_PIN, INPUT_PULLUP); 
  attachInterrupt(digitalPinToInterrupt(TEST_PIN), enc_tick_a, CHANGE);
}

volatile bool int_a = false;
volatile uint8_t val_a = 0;

void enc_tick_a(){
  int_a = true;
  val_a = digitalRead(TEST_PIN);
}

void loop() {
  if (int_a) {
    Serial.println("Interrupt A");
    Serial.println(val_a);
    int_a = false;
  }
}

There's a rotary encoder attached to the pin under test. When I run this code on Arduino Duemilanove, I see the following output for every "tick" of the encoder:

Interrupt A
0
Interrupt A
1

Continuing to turn the encoder, I see what one would expect:

Interrupt A
0
Interrupt A
1
Interrupt A
0
Interrupt A
1
Interrupt A
0
Interrupt A
1

I have an identical hardware setup but with an Arduino Nano Every chip that produces the same output.

When I test with the Arduino Nano 33 BLE chip I'm not seeing falling-edge interrupts. The output from the above test program is only:

Interrupt A
1

Multiple ticks of the encoder yields

Interrupt A
1
Interrupt A
1
Interrupt A
1
Interrupt A
1
Interrupt A
1
Interrupt A
1
Interrupt A
1

As you can see, it appears my interrupt is only firing on 0->1 transitions but not 1->0 transitions.

If I change TEST_PIN to 2 (the other leg of the encoder) I observe the same thing.

Am I missing something fundamental here, or is attachInterrupt(x, x, CHANGE) not working as expected on the BLE nano?

Thank you!

[pbaughman]

Some additional testing:

If I change CHANGE to FALLING in attachInterrupt I see:

Interrupt A
0

So it seems like the board is capable of detecting the falling-edge interrupts, its' just not doing so when the interrupt mode is CHANGE.

[pbaughman]

One additional wrinkle - I see that there's a closed issue describing this same problem that has a merged MR: #68

I believe I'm using the latest master - I've followed the instructions in the README.md file. Is there a way to tell for sure?

[pbaughman]

Final update - I turned up the verbosity when building and saw that I was probably still using the installed version instead of the source version of ArduinoCore-nRF528x-mbedos Upon discovering this, I uninstalled the version installed by the board manager. Now my IDE detects the code installed in the hardware folder of my sketchbook.

Unfortunately trying to build results in the error exec: "/bin/arm-none-eabi-g++": file does not exist

Can someone confirm that the instructions in the README.md are for linux systems only? Are they intended to work on Windows, too? I suspect I'm not on the happy development path here and that's why I'm encountering problems.

[pbaughman]

Alright, it was a real challenge to get this working on a Windows system - I will post the steps I followed in case they are helpful to someone else:

1. Make sure the BLE Nano board is installed using the Arduino IDE
2. In the folder C:\Users\Username\AppData\Local\Arduino15\packages\arduino\hardware rename the folder mbed to mbed_bak This will prevent the IDE from using the installed sources for the BLE board, but still leave the tools installed in C:\Users\Peter\AppData\Local\Arduino15\packages\arduino\tools
3. In your Arduino sketch folder (C:\Users\Username\Documents\Arduino) on my system, follow the instructions in README.md to create a hardware/arduino folder containing mbed and the ArduinoCore-API source

Then, for some reason I also had to edit C:\Users\Username\Documents\Arduino\hardware\arduino\mbed\platform.txt and change

tools.bossac.path={runtime.tools.bossac-1.9.1-arduino1.path}

to

tools.bossac.path=C:\Users\Peter\AppData\Local\Arduino15\packages\arduino\tools\bossac\1.9.1-arduino1

Once you've made all of those change, make sure to restart your IDE.

You should now (hopefully) be able to build with the source version of ArduinoCore-nRF528x-mbedos

[facchinm]

Hi @pbaughman ,
sorry but I've seen it just now that you solved the issue by yourself 🙂
For future reference, you can have both the official and the git version of a core installed sideways.
What you need to do is to create a folder in your sketchbook called hardware/$foo/ and clone the core there.
For example, for this core, given C:\Users\M\Documents\Arduino as sketchbook path, it would run like this:

cd C:\Users\M\Documents\Arduino
mkdir -p hardware\arduino-git
cd hardware\arduino-git
git clone https://github.com/arduino/ArduinoCore-nRF528x-mbedos mbed
#for this particular core you should copy the "api" folder from another installation since it's just a placeholder in git

Restart the IDE and you are done; this way there's no chance to lose your modification in case of update.