Using extra pin as digital output

Other Hardware 3rd Party Boards
1

Hi All,

I'm trying to set up my first board with the Leonardo firmware and basic design concepts.

For what I need I'm short 1 digital pin and I want to pinch it from somewhere. I also want to keep the standard Leonardo firmware/bootloader because changing the firmware is above my skill level.

My thoughts on where to get the extra digital output include:

  • HWB
  • TXLED
  • RXLED

Or can I convert an analog pin to digital?

Any ideas which would be the easiest to use and how to keep it compatible with the current Leonardo firmware??

Thanks for your help.

2

Or can I convert an analog pin to digital?

I don't own a Leonardo board but I suspect like most all the other arduino boards, analog input pins can be used as digital pins, just use the analog pin names in the digital commands:

pinMode(A0, OUTPUT);
pinMode(A0, INPUT);
pinMode(A0, INPUT_PULLUP);
digitalRead(A0);
digitalWrite(A0, HIGH);

etc
Lefty

3

Thank you, that's a bit too easy.

Should I then permanently connect pin 33 HWB to ground via 10K resistor as shown on the Leonardo schematic? Or will this cause the bootloader to keep resetting?

4

Thanks for this info. I have a project on an Arduino Pro Mini where I was 2 pins short (everyone appreciates an audible alarm and then a button to silence/acknowledge it!).
Now I will repurpose all 6 of the analog inputs as digital inputs and leave pins 1 & 2 available for serial communications in the future (Should I need it). That's puts me up 2 pins now!
I won't even mess with the two 'bonus' analog pins in the center of the board.