Hello,
Hate to reopen this but it seems as if it was never really solved. @bembu_account, did you manage to figure out how to change the Serial1 TX_BUFFER_SIZE ?
First off I am using a Mac.
The regular advice has been to change the Serial_TX_BUFFER_SIZE in HardwareSerial.h within "/Applications/Arduino.app/Contents/Java/hardware/arduino/avr/cores/arduino", however, this doesn't decrease the amount of SRAM or change anything when Serial.availableForWrite() is called. Therefore, it doesn't seem like Arduino is even using this path. Obviously though since I am using an SAMD21 board I found some advice to find the path Arduino is reading from by choosing a sketch example under my board, okay good.
As I said I also am using a SAMD21 board (feather m0) and the HardwareSerial.h file under "/Users/userName/Library/Arduino15/packages/adafruit/hardware/samd/1.2.1/cores/arduino"
seems to use the native HardwareSerial.h file:
#ifndef HardwareSerial_h
#define HardwareSerial_h
(as I cannot find any other place to change the Serial TX_BUFFER_SIZE). I do see an option to change the SERIAL_BUFFER_SIZE in RingBuffer.h (164 currently). And by changing that at least the SRAM went down so I know I am in the right directory but that doesn't seem to offer an option to modify the TX buffer.
I've also seen that by the version I am on (1.8.5) apparently you can also change the TX buffer sizes for Serial/Serial1 independently from one another, is this true? That also is important for me.
Thanks