Using MCUdude's MegaCoreX you should be able to use all four hardware serial ports. You can alternatively modify the arduino core files, but that is a lot more involved.
SoftwareSerial on most arduino's is not capable of receiving its own output.
Using MCUdude's MegaCoreX you should be able to use all four hardware serial ports. You can alternatively modify the arduino core files, but that is a lot more involved.
SoftwareSerial on most arduino's is not capable of receiving its own output.