ReverthCameraSerial.ino

// #include <SoftwareSerial.h>

#include <SD.h>
#include <SPI.h>

#define CAMERA_RX 3
#define CAMERA_TX 2

#define BAUD_RATE 115200
#define chipSelect 4

File logFile;

void setup() {

  pinMode(8, INPUT_PULLUP);
  if(chipSelect != 10) pinMode(10, OUTPUT); // SS on Uno, etc.

  // put your setup code here, to run once:
  Serial.begin(BAUD_RATE);
  Serial1.begin(BAUD_RATE);
  while (!Serial) {
    ; // wait for serial port to connect. Needed for native USB port only
  }

  SD.begin(chipSelect);
  logFile = SD.open("TEST.TXT", FILE_WRITE);

}

void loop() {
  // put your main code here, to run repeatedly:
  if (digitalRead(8) == LOW) {
    logFile.close();
  }

  if (Serial1.available()) {
    Serial.write(Serial1.read());
  }
  
  if (Serial.available()) {
    byte r = Serial.read();
    Serial1.write(r);
    logFile.write(r);
  }

}