Hoermann HCP protocoll test on ESP32 (syncbreak hack)

hcp.cpp

/* vim:set sw=2: */

#include <Arduino.h>

#define RX2 21
#define TX2 22
#define DIR 17

int rx = 0;

void enable_transmitter() {
  // set output for RS485 Transmitter
  digitalWrite(DIR, HIGH);
}

void disable_transmitter() {
  // clear output for RS485 Transmitter
  digitalWrite(DIR, LOW);
}

void syncbreak()
{
  Serial2.end();
  gpio_reset_pin(GPIO_NUM_22); // Hack found here: https://github.com/espressif/arduino-esp32/issues/3032
  pinMode(TX2, OUTPUT);
  enable_transmitter();
  digitalWrite(TX2, LOW);
  digitalWrite(LED_BUILTIN, HIGH);
  delayMicroseconds(920);
  digitalWrite(TX2, HIGH);
  digitalWrite(LED_BUILTIN, LOW);
  disable_transmitter();
  Serial2.begin(19200, SERIAL_8N1, RX2, TX2);
}

void setup()
{
  pinMode(LED_BUILTIN, OUTPUT);
  pinMode(DIR, OUTPUT);
  digitalWrite(DIR, LOW);
  Serial.begin(38400);
  Serial2.begin(19200, SERIAL_8N1, RX2, TX2);
  delay(100);
}

void loop()
{
  syncbreak();
  enable_transmitter();
  Serial2.write(0x80);
  Serial2.write(0x83);
  Serial2.write(0x29);
  Serial2.write(0x00);
  Serial2.write(0x10);
  Serial2.write(0x3A);
  disable_transmitter();
  delay(50);
  while(Serial2.available() > 0) {
    rx = Serial2.read();
    Serial.println(rx, HEX);
  }
  Serial.println("Wait for next round");
  delay(1000);
}