ESPEasy/lib/SC16IS752/example/SPI_RECEIVE/README.md

SPI_RECEIVE

Connect TX(A-CH) and RX(B-CH) with a short wire
Connect TX(B-CH) and RX(A-CH) with a short wire

Connections should be as short as possible

Channel baudrate

You can specify different baudrates for channel A and channel B

Sketch of the other side

#define baudrate 9600L

void setup() {
  Serial.begin(baudrate);
}

void loop() {
  char buf[64];
  sprintf(buf,"Hello Wold, Baudrate is %ld", baudrate);
  Serial.println(buf);
  //Serial.println("Hello this is Arduino");
  delay(1000);
}