This was introduced in 50bc7867, but
doesn't seam to be intended, because the previously the macro was only
defined in the source code.

Fix variant docs Issue #507

USB CDC: Line Info Per Instance

Updated naming of MKR boards

Updated naming of boards

Updated some naming of the products @facchinm

Updated some names of MKR boards, see changes! @facchinm

Update I2S.cpp to work with RTCZero library

I2S.cpp configures the clock without specifying what to GLCK->DIVSEL bit. This causes issues when the bit is set to 1 by other libraries such as RTCZero. Explicitly setting this value fixes the problem.

* Document how to add the required link to ArduinoCore-API.

Related to https://github.com/arduino/ArduinoCore-API/issues/96

.

* Update README.md

Co-authored-by: per1234 <accounts@perglass.com>

* Update README.md

Co-authored-by: per1234 <accounts@perglass.com>

* Update README.md

Co-authored-by: per1234 <accounts@perglass.com>

* Update README.md

Co-authored-by: per1234 <accounts@perglass.com>

Co-authored-by: per1234 <accounts@perglass.com>

This is usually not a problem becuase we use the arm-none-eabi-gcc compiler
thas has type `uint32_t` aliased to `unsigned long`. Anyway this is not
mandatory in general, and the compiler may choose to alias `uint32_t` with
`unsigned int` as it happens with llvm/clang.

Since we use clangd as language server on the Arduino IDE 2.0 the
Serial_ object and all the derived instances (Serial, SerialUSB, ...) are
not available in code-completion suggestions.

Add missing #define statements when compared to AVR library.
Support for readbytes with a byte/uint8_t buffer

Make SerialCDC inherit from HardwareSerial

Fix USBDevice.connected()

* Fix arduino/ArduinoCore-samd#661
* connected() did not return the USB connected state, but essentially a
  random value.

As suggested by @thiagoralves

Fix legacy `upload.network_pattern` rules

Remove programmer properties from openocd upload pattern

Platform properties may be associated with a specific programmer selection in the programmers.txt configuration file. These properties can be used in the platform.txt patterns for the actions that use the programmer:

- `program`
- `erase`
- `bootloader`

However, those properties are not expanded in the `upload` pattern, since it does not use the programmer:

https://arduino.github.io/arduino-cli/dev/platform-specification/#programmerstxt

> These properties can only be used in the recipes of the actions that use the programmer (erase, bootloader, and program).

While enhancing the ability to make programmer-specific configuration of the patterns, programmer-associated properties were introduced into `tools.openocd.upload.pattern`, which caused uploads to fail for the "Arduino Zero (Programming Port)" board:

```
Unexpected command line argument: {extra_params}
```

The upload pattern is hereby reverted to the previous working configuration, leaving the beneficial changes to the other patterns.

fix Serial.flush() blocks forever #597

UART: restore default buffer size to 256 bytes

Document SAMD_AnalogCorrection library's 12 bit resolution requirement

Fix I2C Master hang when communicating with bad I2C slaves.

SPI: restore 12MHz as maximum frequency

Fix to a proper MCU name in variant.cpp for Arduino Nano 33 IoT.

Restructure programmers by removing hardcoded build.openocdscript

* The aynchronous nature of the DRE and TXC interrupt flags
  causes issues (lockups) when the TX DATA register is empty on start
  and a flush is issued. Simply looking at the DRE prior to
  waiting for TXC is insufficient because the data register
  may well be empty but the shift register could still contain
  data, in this case SERCOM::flushUART() would return before TXC
  has been raised thus before flushing is complete.
* bool added to SERCOM.h to indicate when it is ok for
  SERCOM::flushUART() to wait for the TXC flag. This flag is
  set when any data is written to the data register via
  SERCOM::writeDataUART(). It is cleared when a flush is done.

Fixes #650

add architecture specific flag to compiler.S.flags