platform: Add USB device MaxPower default setting

Set the USB descriptor strings. I accepts UTF-8 strings withcodepoints up to 16 bit.  void setup() {    USBDevice.setManufacturer("MyManufacturer");    USBDevice.setProduct("MyProduct");  }

Huge USB configurations might need more than 256 bytes for theconfig descriptor buffer. MIDI devices with 16 virtual portsgrow the descriptor to 600+ bytes.This call replaces the built-in buffer with the supllied buffer. Thecall copies the content of the old buffer to the new buffer:  uint8_t buf[1024];  USBDevice.setDescriptorBuffer(buf, sizeof(buf));

TC6_CH0, TC6_CH1, TC7_CH0, TC7_CH1 on SAMD21JTCC0_CH6, TCC0_CH7, TCC1_CH4, TCC1_CH5, TCC1_CH6, TCC1_CH7, TC6_CH0, TC6_CH1, TC7_CH0, TC7_CH1 on SAMD51J

Enable TC6 & TC7 for __SAMD21J18A__

Added Additonal Timers

tinyusb: Allow to replace the built-in descriptor buffer

tinyusb: Allow to set the USB manufacturer/product identifiers

add Descriptor to setManufacturer/setProduct

follow up to pr#172

This allows to compose the descriptor programmatically. The calling codecan compose a MIDI descriptor with up to 16 virtual wires/jacks atinitialization time.Tested with the tinyusb -> MIDI -> midi_test example. This commit shouldnot change any behavior, future extensions of the calling MIDI devicewill make use of it.

New boards could have DAC0 & DAC1 on different pins. DAC0 & DAC1 pins are defined on each variant.h file, so it is not needed to reference to pins A0 & A1. With this change the code is more generic. Changes affect to analogWrite & analogRead functions.

Change references from A0 & A1 to DAC0 & DAC1

tinyusb: MIDI - split descriptor initializer into individual sections

…r stuff! (servo is TC1)

allow PDM mic on pybadge edgechange pyportal backlight timer

Added a isBusy() method to SPI calls to allow non-blocking polling of…

I think this file doesn't match the circuit diagram listing athttps://cdn-learn.adafruit.com/assets/assets/000/047/156/original/circuit_playground_Adafruit_Circuit_Playground_Express_Pinout.png?1507829017.It causes the interrupt pin checking code in ArduinoLowPower to fail, meaning it won't listen to interrupts from button A. Button B works fine.

Add additional EINT fixes for PA{0,1,30}, PB{3, 23}.

Fix EINT listing for pin 4

Co-authored-by: Sandeep Mistry <s.mistry@arduino.cc>

add new variant

Attempting to cast to a `volatile uint32_t` does nothing different from cast to a `uint32_t`,with the exception of **_looking like_** it's accessing a register.

Untested...

Cast to integral type ignores qualifier `volatile`

Use same51 from cmsis atmel tool

Fix [-Wrestrict] bug

Fixes#287The warnings look like:```      Line 338 Char 37      warning: 'void* memcpy(void*, const void*, size_t)'                writing to an object of type 'struct DmacDescriptor'               with no trivial copy-assignment [-Wclass-memaccess]```

* add rotary trinkey rev B* add slide trinkey* proximity sensing trinkey* update variant to shipping* forgot one!* fix two typos* fix up slide trinkey for rev B