SoftwareSerial library not compatible for >20MHz processors

[ashishsk]

I am using the Feather M4 Express (ATSAMD51 controller on it) with the Serial CAN board and I am unable to compile the example code due to the error below.

lib/SoftwareSerial/SoftwareSerial.cpp:362:2: error: #error This version of SoftwareSerial supports only 20, 16 and 8MHz processors

[ktetsuo]

ref: #10