You could potentially modify the firmware to to this.

But, can I ask what the purpose of this change would be? What is it that you’re doing that requires you to toggle the pen up and down repeatedly?

Once the pen is in the pen-up position (which you can set from your computer before starting the session), there should not be any need to manually lower or raise the pen again while setting up different pens and papers, even during a full day of use. So, I’m not sure exactly what it is that you’re doing.

It is possible to hard code something like this into custom firmware if that’s your preferred way of coding. But, it is also something that could be done with a custom Inkscape extension, a modification to one of ours, or an independent script on the computer — without any changes to the firmware.

What are you doing when inserting a pen that requires you to lower it?

(We have occasionally seen people insert a pen in the “pen down” position, and then manually change the pen-down setting, but that’s the opposite of the recommended procedure.)

The EBB firmware is open source, and hosted in the EggBot repository: https://github.com/evil-mad/EggBot/tree/master/EBB_firmware

The other I/O pins above the servo connector are not polled by default, but you can poll them through software, for example by modding an extension. We would always recommend to use the existing interface rather than modifying the firmware, especially for things like this that are easily done through software: http://evil-mad.github.io/EggBot/ebb.html