analog and serial issue

[Makeblock-official]

1. no analog output on 7
2. program keep go into serial error irq if serial connect to nothing,
   the function clearStatusUART seems not working

[cmaglie]

Hi @Makeblock-official

1. pin 2 and 7 are not supposed to have PWM
2. Yesterday I've published the release 1.6.1 of the SAMD core, that contains this fix to a similar problem: 49fe438
   may it be of any help for you?

[cmaglie]

closing for lack of feedback, if the problem persists please provide more details on how to reproduce the bug.