Trying to read a text field from my Thingspeak channel (text) and display it using arduino giga display shield.

Matlab Visualization Code (works properly)

My first 3 lines of information display properly on my giga display shield.

The 4th line which is supposed to be a timestamp stored in my field as text (ex:

Displays as -1, not the text timestamp I am looking for. Any help is appreciated.

% Read the last entry and its timestamp
[data, timestamps] = thingSpeakRead(x, 'NumPoints', 1);

% Add a timezone offset of 5 hours
localTime = timestamps - hours(5);

% Display the local timestamp as text
text(0.5, 0.5, datestr(localTime), 'FontSize', 20, 'HorizontalAlignment', 'center');
axis off;


Note - sensitive info replaced with X

Arduino code
#include <WiFi.h> //library for connecting to WiFi
#include <ThingSpeak.h> //library for reading data from ThingSpeak
#include "Arduino_GigaDisplay_GFX.h" //library for using the GigaDisplay shield


//define WiFi credentials
const char* ssid = "x";
const char* password = "x";
WiFiClient client;
String textData = "";

//define ThingSpeak channel IDs and read APIs
unsigned long lakeChannelID = x;
const char* lakeReadAPI = "x";


//define GigaDisplay object
GigaDisplay_GFX display;

#define BLACK 0x0000
#define WHITE 0xFFFF
#define NEW 0xFF6B35

void setup() {
  //initialize serial communication for debugging
  Serial.begin(9600);


  //connect to WiFi
  WiFi.begin(ssid, password);
  Serial.print("Connecting to WiFi...");
  while (WiFi.status() != WL_CONNECTED) {
    delay(1000);
    Serial.print(".");
  }
  Serial.println("Connected!");
  Serial.print("IP address: ");
  Serial.println(WiFi.localIP());

  ThingSpeak.begin(client);  // Initialize ThingSpeak
  display.begin();
  }


void loop() {

  float homeTemp = ThingSpeak.readFloatField(lakeChannelID, 8, lakeReadAPI);
  float lakeTemp1 = ThingSpeak.readFloatField(lakeChannelID, 1, lakeReadAPI);
  float lakeTemp2 = ThingSpeak.readFloatField(lakeChannelID, 2, lakeReadAPI);
  float lakeTemp3 = ThingSpeak.readFloatField(lakeChannelID, 3, lakeReadAPI);
  float lakeTemp4 = ThingSpeak.readFloatField(lakeChannelID, 4, lakeReadAPI);
  float lakeTemp5 = ThingSpeak.readFloatField(lakeChannelID, 5, lakeReadAPI);
  float lakeTemp6 = ThingSpeak.readFloatField(lakeChannelID, 6, lakeReadAPI);
  String textData = ThingSpeak.readStringField(lakeChannelID,7, lakeReadAPI);
  float lakeTempOutAvg = (lakeTemp1 + lakeTemp2 + lakeTemp3)/3;
  float lakeTempUnderAvg = (lakeTemp4 + lakeTemp5 + lakeTemp6)/3;
  long statuscode = ThingSpeak.getLastReadStatus();
  if (statuscode == 200)


   { 
    //print temperature data to serial monitor for debugging
  Serial.print("Home Outside Temp: ");
  Serial.println(homeTemp);
  Serial.print("Lake Outside Temp: ");
  Serial.println(lakeTemp1);
  Serial.print("Lake Outside Average: ");
  Serial.println(lakeTempOutAvg);
  Serial.print("Lake Under Average: ");
  Serial.println(lakeTempUnderAvg);
  Serial.print("Last Read: ");
  Serial.println(textData);
  //clear display and set cursor to top left corner
 
  display.setRotation(1); // -90 degrees rotation
  display.fillScreen(BLACK);
  display.setTextColor(NEW);
  display.setTextSize( 5);
  display.setCursor(50, 10); // Adjusted for rotated display
  display.print("Home Outdoors");
  display.setCursor(200, 60); // Adjusted for rotated display
  display.print(homeTemp, 1);
  display.print(" F");
  display.setCursor(50, 120); // Adjusted for rotated display
  display.print("Lake Outdoors");
  display.setCursor(200, 170); // Adjusted for rotated display
  display.print(lakeTempOutAvg, 1);
  display.print(" F");
  display.setCursor(50, 230); // Adjusted for rotated display
  display.print("Lake Under House");
  display.setCursor(200, 280); // Adjusted for rotated display
  display.print(lakeTempUnderAvg, 1);
  display.print(" F");
  display.setCursor(50, 340); // Adjusted for rotated display
  display.print("Data Last Reported");
  display.setCursor(200, 390); // Adjusted for rotated display
  display.print(textData);

 
  //wait for 10 seconds before updating again
  delay(10000);
   }
   }

//Code sourced from ThingSpeak and GigaDisplay libraries.

[Christopher Stapels]

It would be easier on the API for you to use ThingSpeak.readMultipleFields(channelNumber, readAPIKey) to get multiple fields in one shot. See this example for code.

Then you arent sending a burst of seven seperate requests to the server in a few miliseconds.

By the fourth line, I think you mean

 display.print("Data Last Reported");
  display.setCursor(200, 390); // Adjusted for rotated display
display.print(textData);

which comes from this

  String textData = ThingSpeak.readStringField(lakeChannelID,7, lakeReadAPI);  

I suggest you use the created at timestamp, unless things get stored in your channel at a different time than when they were measured.

   String createdAt = ThingSpeak.getCreatedAt(); // Created-at timestamp   

Otherwise Im afraid field 7 doesnt have the data you think it does ( hence the -1) If you share your channelid (and its public), I could take a look a the data. and try to help. I understand if the channel is private that you might not want to share.

[Arlian]

@Christopher Stapels, Thank you. I changed my code to include ThingSpeak.readCreatedAt() and that solved the issue.