Increasing the Ring buffer size to support Modbus protocol

[dhineshkumarmcci]

As per the spec of Modbus protocol, it is possible to read 125 registers at once. With the current version of SAMD BSP, BAD CRC has been thrown on reading more than 79 registers (163 bytes). This is because of the limit in Serial buffer size as 164.

To read more than 79 registers (up to 125), we have to increase the serial buffer size SERIAL_BUFFER_SIZE to 256 in RingBuffer.h. The coding part to be updated is below:

ArduinoCore-samd/cores/arduino/RingBuffer.h

Line 28 in 31c3b29

#define SERIAL_BUFFER_SIZE 164

On increasing the serial buffer size to 256, Catena 4470 was able to read 125 registers.

[terrillmoore]

Please submit a pull request, thanks.