DMX2021.ino

/**
   Arduino DMX Controller
   Playful Technology (c) 2019

   Demonstrates how an Arduino + DMX shield can be used as a device to trigger
   lighting and other stage effects, either based on direct input (e.g. button press)
   or via a JSON payload received on serial port connection, such as
   might be transmitted by Node-RED.

   Tested using the Conceptinetics Arduino DMX shield available from
   https://www.tindie.com/products/Conceptinetics/25kv-isolated-dmx-512-shield-for-arduino-r2/
   but should work with other DMX shields, or even DIY DMX-shields using MAX485 chip as described at
   https://playground.arduino.cc/DMX/DMXShield/
*/

// INCLUDES
// Modified version of the DMX library based on https://github.com/PaulStoffregen/DmxSimple
#include "src/DMXSimple/DMXSimple.h"
// JSON serialisation/desserialisation library download from https://arduinojson.org/
#include <ArduinoJson.h>

// CONSTANTS
// The pin on which Arduino will transmit DMX packets
const byte dmxTransmitPin = 48;
// Used to switch between Master/Slave modes
//const byte modeSelectPin = 2;

void setup() {
  // Serial connection is used to receive DMX request as JSON payload from another device, e.g. Node-RED
  Serial.begin(9600);

  // Print out some help text to show example payload expected
  Serial.println("Send DMX channel/values as JSON payload in the following format:");
  Serial.println("{\"channels\":[");
  Serial.println("  {\"channel\":1,\"value\":255},");
  Serial.println("  {\"channel\":3,\"value\":128}");
  Serial.println("]}");

  /*  // If using the Conceptinetics Arduino DMX shield, set to "DMX Master" mode
    // (i.e. sets the line driver to write mode rather than slave mode)
    pinMode(modeSelectPin, OUTPUT);
    digitalWrite(modeSelectPin, HIGH);*/

  // Specify the pin that the Arduino will use to communicate with the DMX shield
  DmxSimple.usePin(dmxTransmitPin);

  // By default, DmxSimple only sends up data in DMX channels that have actually been
  // used. Some DMX devices require the whole 512byte message to be sent, which can be
  // done as follows:
  DmxSimple.maxChannel(512);

}

void loop() {
  // For more complex effects, we'll process a JSON encoded DMX string
  // containing an array of channel:value pairs received over the serial port
  if (Serial.available()) {
    // Create a new JSON document
    DynamicJsonDocument doc(512);
/*StaticJsonDocument<512> doc;
    // set timeout to 10 seconds
//    Serial.setTimeout(10000);
deserializeJson(doc, Serial);*/
    // Parse any incoming data received over the serial connection
    DeserializationError error = deserializeJson(doc, Serial);
    // Check that the data is valid
    if (error) {
      Serial.print(F("deserializeJson() failed: "));
      Serial.println(error.c_str());
      return;
    }

//deserializeJson(doc, Serial);

/*for (JsonObject elem : doc["channels"].as<JsonArray>()) {

  int channel = elem["channel"]; // 1, 3
  int value = elem["value"]; // 255, 128

      Serial.println(channel);
      Serial.println(value);
      // Write each value to the correct channel
      DmxSimple.write(channel,value);
      }*/



    // Parse the array of channel:values from the received string
    JsonArray array = doc["channels"].as<JsonArray>();
    for (JsonVariant v : array) {
      Serial.println(v["channel"].as<int>());
      Serial.println(v["value"].as<int>());
      // Write each value to the correct channel
      DmxSimple.write(v["channel"].as<int>(), v["value"].as<int>());
    }
  }
}