Canvas graph not plotting

jedidiahelectronics · May 12, 2025, 1:10pm

Hello, I have finished coding and the program runs well as indicated by the strategically-set labels I have set, but no graph is being plotted. I need help on how ensure its plotted. Thank you.

TIMAI2 · May 12, 2025, 1:16pm

Looks like you have three opportunities for your canvas to not draw a line:

xbefore = x , ybefore = y
Canvas paint colour the same as canvas background colour ? You set paint colour to green after you call drawline.
Clearing the canvas if x>CanvasWidth, and setting x and xbefore to 0

ABG · May 12, 2025, 3:12pm

Why exactly 10 bytes?

Why do you split incoming message into a global variable, and then ignore it?

What is your split character? Are you trying to split at \n (Line Feed)?

Show us your sketch code.

jedidiahelectronics · May 14, 2025, 12:54pm

Yes am trying to split at \n. I've changes to from 10 to -1
Tempgraphtrial.aia (13.9 KB)
TEMPGRAPHTRIAL.ino (990 Bytes)

ABG · May 14, 2025, 2:07pm

This is how you are sending your temperature:


void loop() {
  // Read the analog value from LM35
  int analogValue = analogRead(lm35Pin);

  // Convert to voltage (assuming 5V and 10-bit ADC)
  float voltage = analogValue * (5.0 / 1023.0);

  // Convert voltage to temperature in Celsius
  float temperatureC = voltage * 100;

  // Send temperature via Serial (Bluetooth)
  Serial.println((int)temperatureC);

  // Display temperature on LCD
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("Temp: ");
  lcd.print(temperatureC, 1); // Show 1 decimal place
  lcd.print(" C");

  delay(1000);  // Update every 1 second
}

You are sending one number per line, with nothing extra on the line.

This is how you are trying to receive and process your messages:

You are looking for non-existent commas.
You also forgot to increment x for your graph, so your graph is just a vertical line all the way at the left.

This draggable block should address both problems:

P.S. I did not address the possible need to address vertical scaling, in case there is a big mismatch between the range of Y pixel ranges and incoming temperature values.

Also, there is a hook in the AI2 GraphData component to read such a Bluetooth data stream and plot it directly, with automatic scaling.