variant.cpp Feather M4 points to PA27 for USB DP (D+) pin

[wa1tnr]

Feather M4 Express USB pin mapping in variant.cpp is presently incorrect on a single pin (DP aka D+).

https://github.com/adafruit/ArduinoCore-samd/blob/master/variants/feather_m4/variant.cpp#L92

Presently:
{ PORTA, 27, PIO_COM, PIN_ATTR_NONE, No_ADC_Channel, NOT_ON_PWM, NOT_ON_TIMER, EXTERNAL_INT_NONE }, // USB/DP

Suggested:
{ PORTA, 25, PIO_COM, PIN_ATTR_NONE, No_ADC_Channel, NOT_ON_PWM, NOT_ON_TIMER, EXTERNAL_INT_NONE }, // USB/DP

The schematic suggests PA25 for this pin function, rather than PA27 (which seems to be n/c in the schematic).

Supporting evidence below, including commit a7277e6
from DeanM in 2017, October.

Thanks! from github user wa1tnr

---

Feather M4 Express, schematic diagram:
https://learn.adafruit.com/assets/57242

Correctly identified variant:
https://github.com/adafruit/ArduinoCore-samd/blob/master/boards.txt#L637

Further evidence in the file's own history, first instance:
f618756#diff-8b717367c9aabdaaacc859b5b8471752L74

Tracing back, found an instance where it was correct:

ArduinoCore-samd/variants/feather_m4/variant.cpp

Line 177 in a7277e6

{ PORTA, 25, PIO_COM, PIN_ATTR_NONE, No_ADC_Channel, NOT_ON_PWM, NOT_ON_TIMER, EXTERNAL_INT_NONE }, // USB/DP

So it (DP aka USB D+, PA25) was correctly mapped, in commit a7277e6:

commit a7277e6
Author: dean [email protected]
Date: Fri Oct 13 18:15:20 2017 -0400

DM: adding feather m4

Didn't find where the change was introduced.

[ladyada]

ok - it isnt necessary btw, its a placeholder