A discussion in the Music library brainstorm thread, as well as in this thread and on IRC, has come to the conclusion that Arduino pins 5 and 13 are desirable to use for the two speaker leads.
@davidperrenoud has proposed the creation of a DIY Arduboy Kit, possibly using a Pro Micro board. Based on his observations, in order to best accommodate the limitations of the Pro Micro, I'll summarise the desired pin mappings for the production Arduboy as follows:
- Speaker leads: 5 (PC6) and 13 (PC7)
- Display DC: 4 (PD4)
- Display CS: 6 (PD7)
- Display RST: 12 (PD6)
- Button A: 7 (PE6)
- Button B: 8 (PB4)
- D-Pad buttons: A0 (PF7), A1 (PF6), A2 (PF5), A3 (PF4)
- RGB LED: 9 (PB5), 10 (PB6), 11 (PB7)
- Battery monitor (if implemented): A4 (PF1) or A5 (PF0)
Note that all the display control pins are mapped the same as the current Dev Kit, making it a bit easier for a common library.
The order of the assignment of the three RGB LED colors to pins 9, 10 and 11 is arbitrary but if one color is considered less important than the other two, it should be put on Pin 11, because Pin 11 isn't available on a Pro Micro.
I'd suggest blue on Pin 11. Blue generally doesn't have much meaning but red/green can indicate stop/go, no/yes, bad/good, etc. Also, a two color red/green LED could be shifted from red, through various shades of orange and yellow, to green to indicate, for instance, a character's health or weapon's power level.
I myself have full color vision so I can't speak for those with a red/green color deficiency, who might argue that having green/blue or red/blue is more desirable. However, I'd suggest that a kit that could only support two colors have spots for both a bi-color LED and two single color LEDs to better accommodate those people with color vision deficiencies.
I'm still not sure which button is A and which is B but note that the one we want to be capable of generating a standard Arduino int.4 interrupt should go on Pin 7 (PE6).