gbulmer
Moderator
I had a look at the Eagle CAD for maple mini, and AFAIK, it only uses three signal pins, D+/D- for USB data, and DISC which is connected to pin 46, PB9/TIM4_CH4.
Maple uses four signals, it uses PC11, pin 52, to connect to USB_P, which has no counterpart on maple mini.
I am all in favour of freeing more pins for me to use!
So will PC11 on Maple be freed up, and specifically unused by USB software, e.g. bootloader, once the Maple mini is released?
(I'd really like to free the pin.)
jessb
LeafLabs
So USB_P is not really actively used on Maple; it's to tell whether or not the USB is plugged in so ostensibly it could be useful, but the bootloader does not rely on it. However there's not really a plan to break it out to a GPIO in future revisions, as we're trying to keep the hardware as stable as possible from here on out. sorry!
gbulmer
Moderator
So USB_P is not really actively used on Maple; it's to tell whether or not the USB is plugged in so ostensibly it could be useful, but the bootloader does not rely on it.
Okay, so I can use it without any risk of interfering with the bootloader.
However there's not really a plan to break it out to a GPIO in future revisions, as we're trying to keep the hardware as stable as possible from here on out.
That is a reasonable answer.
I think you are right to try to keep Maple's hardware interface stable.
My question was, effectively, is it safe to assume that pin will NOT get used by Maple compatible USB bootloaders?
I think the answer is, the pin isn't on a GPIO header, so it isn't certain it will never get used, but it isn't used now, and there are no plans to use it currently in the works.
It might be nice to have one page which documents the status of pins across the whole Maple range. This one might be in different groups on each product. I'd add a new 'column' to represent a product version when a pin moves from one category, or physical location, to another.
Edit: (full disclosure: I am not a member of the LeafLabs staff)
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