Set up Wio Terminal as MQTT Display for machinechat JEDI One Sensor Data


This project sets up a Seeed Wio Terminal as an MQTT display that subscribes to live sensor data on a machinechat JEDI One IoT data platform over WiFi. Arduino is used to implement the Wio Terminal application and JEDI One is installed and running on a Raspberry Pi 4.


    Raspberry PI 4 Model B with 4GB SDRAM
  • Seeed Wio Terminal
    Wio Terminal is a standalone Arduino/MicroPython compatible SAMD51-based microcontroller evaluation platform with WiFi/Bluetooth powered by a Realtek RTL8720DN. It is equipped with a 2.4” LCD Screen, onboard IMU(LIS3DHTR), Microphone, Buzzer, microSD card slot, Light sensor, and Infrared Emitter(IR 940nm).


  • JEDI One
    JEDI One is a ready-to-use IoT data management software solution. Capabilities include: collect data from sensors, devices and machines; build intuitive real-time and historical data and system view dashboards; create rules to monitor and respond to data conditions automatically; receive alert notifications by email and SMS.
  • Arduino
    Arduino is an open-source electronics platform based on easy-to-use hardware and software.


The project uses a Wio Terminal to demonstrate an external MQTT display connected over WiFi to a Raspberry Pi 4 running machinechat’s JEDI One IoT data platform. Arduino is used to implement the code running on the Wio Terminal. The Wio Terminal is set up to connect to the MQTT broker running on the JEDI. Once connected, it subscribes to temperature and humidity sensor data being collected by the JEDI One. The Wio Terminal’s LCD display is then used to show temperature / humidity data, a line chart of the last 50 sensor readings, and the most recent timestamp. The humidity and sensor data is coming from a previously implemented project, Machinechat with ESP8266 and Amphenol T9602 sensor. The JEDI One is also configured to display the sensor data in widgets on the Sensor Dashboard.

Set up the Wio Terminal platform for the Arduino application

1 - Set up Arduino on the Wio Terminal. See link Getting started with Wio Terminal
note: make sure Realtek RTL8720DN firmware is updated per Update the Wireless Core Firmware

2 - Install libraries needed for application. Add these libraries thru Arduino’s Library Manager:

note: add “Free_Fonts.h” and “arduino_secrets.h” files to project directory (Free_Fonts.h is located in ~/Arduino/libraries/Seeed_LCD_master/examples/320 x 240/All_Free_Fonts_Demo)

3 - Code walkthrough (filename: WioTerminalMQTTDisplay.ino)

Setup LCD display, connect to WiFi network, connect to MQTT broker and parse JSON MQTT messages

 Wio Terminal MQTT data display example 
 This sketch demonstrates using the Wio Terminal to mqtt subscribe to temp and humidity sensor data on the 
 machinechat JEDI One IoT data platform. It uses WiFi to connect to the JEDI One MQTT broker.

#include <rpcWiFi.h>
#include <PubSubClient.h>
#include <TFT_eSPI.h>
#include "Free_Fonts.h"
#include"seeed_line_chart.h" //include the library

TFT_eSPI tft;

// for LCD line chart
#define max_size 50 //maximum size of data
doubles data[2]; //Initilising a doubles type to store data
TFT_eSprite spr = TFT_eSprite(&tft);  // Sprite 

char value[7] = "      "; //initial value
char value2[7] = "      ";
char stamp[40] = "2021-09-01T13:04:34"; 

//#include <ESP8266WiFi.h>
//#include <PubSubClient.h>
#include <ArduinoJson.h>
#include "arduino_secrets.h" 

// Update these with values suitable for your network.
char ssid[] = SECRET_SSID;     // your network SSID (name)
char pass[] = SECRET_PASS;    // your network password (use for WPA, or use as key for WEP)

// MQTT server info for JEDI One
const char* mqttServer = "";
const int mqttPort = 1883;

StaticJsonDocument<256> doc;

int data1;  //data1 of MQTT json message
int data2;  //data2 of MQTT json message
int data3;  //data3 of MQTT json message
int msg = 0;
const char* timestamp = "dummy data";  //the is the MQTT message timestamp (this works)
String recv_payload;

// wio terminal wifi 
WiFiClient wclient;
PubSubClient client(wclient); // Setup MQTT client

void setup_wifi() {

  // We start by connecting to a WiFi network
  Serial.print("Connecting to ");
  WiFi.begin(ssid, pass);

  while (WiFi.status() != WL_CONNECTED) {
  Serial.println("WiFi connected");
  Serial.println("IP address: ");

// mqtt message callback
void callback(char* topic, byte* payload, unsigned int length) {

  tft.setTextColor(TFT_WHITE);   //"clear" old data by rewriting old info in white
  Serial.print("Subscribe topic: ");
  Serial.print("Subscribe JSON payload: ");
  for (int i = 0; i < length; i++) {
    Serial.print((char)payload[i]);     // print mqtt payload

  msg = 1;  //message flag = 1 when new subscribe message received

  deserializeJson(doc, (const byte*)payload, length);   //parse MQTT message
  data1 = doc["data1"];    // data1 is humidity
  data2 = doc["data2"];    // data2 is temp
  data3 = doc["data3"];    // data3 is empty
  timestamp = doc["timestamp"];    //mqtt message timestamp
//  stamp = timestamp;
  strcpy (stamp,timestamp);
  stamp[19] = 0;   // terminate string after seconds
  Serial.println(stamp);     //debug print

  itoa(data1,value,10);  //convert data integer value to character
  tft.drawString(value,200,78);//prints data at (x,y)
  tft.drawString(stamp,60,110); //print timestamp
  recv_payload = String(( char *) payload);  // put payload in string for future use
  //Serial.println("print recv_payload string");   //debug info
  //Serial.println(recv_payload);                  //debug info

void reconnect() {
  // Loop until we're reconnected
  while (!client.connected()) {
    Serial.print("Attempting MQTT connection...");
    // Create a unique client ID using the Wio Terminal MAC address
    String MACadd = WiFi.macAddress();
    MACadd = "WioTerminal" + MACadd;  
    String clientID = MACadd;

    // Attempt to connect
    if (client.connect(clientID.c_str())) {
      // set up MQTT topic subscription
      client.subscribe("datacache/T960981B2D");  // topic needs to be "datacache/" + Device on JEDI One 
    } else {
      Serial.print("failed, rc=");
      Serial.println(" try again in 5 seconds");
      // Wait 5 seconds before retrying

void setup() {
  // setup lcd display
  tft.fillScreen(TFT_WHITE); //Black background
  spr.createSprite(320,110); //try 320x110
  tft.setFreeFont(FF19); //select font
  tft.setTextColor(TFT_RED  );
  tft.drawString("Pump House Data",5,5);//prints string at (10,10)
  tft.drawString("  Temperature:  Humidity:",10,50);
  tft.drawString(" %",237,78);
  tft.drawString(" F",100,78);  
  tft.fillRect(0, 40, 320, 2, TFT_BLACK);
  client.setServer(mqttServer, 1883);  //set mqtt server

Main loop checks if connected, checks for MQTT messages and pushes latest line chart of sensor data to the LCD display

void loop() {
  // check if connected to mqtt
  if (!client.connected()) {
  if (msg == 1) {                         // check if new callback message
    //Serial.println("message flag = 1");  //debug print
    msg = 0;                             // reset message flag
    Serial.print("decoded timestamp = ");
    Serial.print("decoded data1 = ");
    Serial.print("decoded data2 = ");

    // line chart code
    Serial.print("data[].size = ");
    Serial.println(data[0].size());  //debug - print data[] size for line chart
    if (data[0].size() == max_size) {
      for (uint8_t i = 0; i<2; i++){
        data[i].pop();//this is used to remove the first read variable
    data[0].push(1.0 * data1);  //read variables and store in data
    data[1].push(1.0 * data2); 
//    Serial.println(data[0]);   //debug    

    spr.fillSprite(TFT_WHITE);  //clear line chart area
    //Settings for the line graph title
    auto header =  text( 0, 100)
    header.height(header.font_height() );
   // header.draw(); //Header is not used so disabled
    auto content = line_chart(20, header.height()-10); //(x,y) where the line graph begins
                .height(tft.height() - 140) //header.height() * 1.5) //actual height of the line chart
                .width(tft.width() - 20) //actual width of the line chart
                .based_on(0.0) //Starting point of y-axis, must be a float
                .show_circle(false) //drawing a cirle at each point, default is on.
                .value({data[0], data[1]}) //passing through the data to line graph
                .color(TFT_PURPLE, TFT_BLUE) //Setting the color for the line
    spr.pushSprite(0, 130);  //display chart
  Serial.println("debug - in main loop");




4 - Latest source code for the WioTerminalMQTTDisplay.ino application is on github at below link:

Set up the JEDI One

1 - If machinechat JEDI One is not already installed on the Raspberry Pi see below:

2 - Set up the JEDI One as described in project Machinechat with ESP8266 and Amphenol T9602 sensor .

Example JEDI One screenshot.


Seeed’s Wio Terminal makes it easy to implement a low cost full color graphical remote MQTT data display. It’s built-in WiFi and associated Arduino libraries enable a direct connection to the JEDI One MQTT broker running on the Raspberry Pi. machinechat’s JEDI One IoT data management provides MQTT access to any data it is collecting as well as additional processing, alerts or other actions.


1 Like