MIT CharMaker1 extension ultrasonic sensor data graph

MIT App Inventor Help
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1

Hello Everyone, I am trying to show a graph of the data that is recorded by the sensor. As of right now, I haven't added how long I want to register or how to start the record and when to stop, but I wish to do that once I figure out why I cannot see the graph.
I attached all the screens I have right now. If anyone finds the heart to help me, I would deeply appreciate it. The Arduino code has been separated since I was testing if the Bluetooth communication worked; at some point, I will want to put them together, probably in a switch case. Regardless any suggestions are again appreciated.

fellow MITappinvetor

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2

Here is an example of sending random number from Arduino to App via Bluetooth HM-10

Remember that there is a delay between sending the message and displaying the data on the app screen, due to the transmission and the code.

3

You might want to label your data stream with a view as to how hard it will be to separate out the numbers on the receiving end.

Hard:
Distance: 55 cm
(Needs separation at spaces on both sides of the 55)

Easier:
DistanceCM:55
(Separation at the ":" easy with a text split block, item 2 of the resultant list has the 55, item 1 can be checked for identification of the data stream (Distance, humidity, temperature, etc.))

Save your user-friendly formatting for display until you need to display or graph the data.

1 Like
4

Do you mean in the Arduino code?

5

Yes.
When one program (or person) speaks to another, they should choose what they say to make it easily understandable to the other.

1 Like
6

The error I get is this one:
"Argument #7 (edu.mills.appinventor.ChartMaker@55222) to 'edu.mills.appinventor.ChartMaker.DrawLineGraph(java.lang.String,java.lang.String,java.lang.String,com.google.appinventor.components.runtime.util.YailList,com.google.appinventor.components.runtime.util.YailList,com.google.appinventor.components.runtime.WebViewer)' has wrong type (edu.mills.appinventor.ChartMaker) (expected: com.google.appinventor.components.runtime.WebViewer) Note: You will not see another error reported for 5 seconds."

I changed the arduino code to this:
const int pingPin = 6; // Trigger Pin of Ultrasonic Sensor
const int echoPin = 7; // Echo Pin of Ultrasonic Sensor

void setup() {
Serial.begin(9600); // Starting Serial Terminal
}

void loop() {
long duration, cm;
pinMode(pingPin, OUTPUT);
digitalWrite(pingPin, LOW);
delayMicroseconds(2);
digitalWrite(pingPin, HIGH);
delayMicroseconds(10);
digitalWrite(pingPin, LOW);
pinMode(echoPin, INPUT);
duration = pulseIn(echoPin, HIGH);
cm = microsecondsToCentimeters(duration);
Serial.print(cm);
Serial.print("\n");
delay(100);
}

long microsecondsToCentimeters(long microseconds)
{
return microseconds / 29 / 2;
}

It seems to me that the problem is elsewhere... I really do not know how to proceed...

Also another thing I noticed is that the first time it writes in the box it gets [1,2,3,4,5,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0] and after I click on testble I get [91,57,49,44,32,53,53,44,32,53,49,44,32,52,52,44,32,51,50,44]

I followed mostly this tutorial (https://appinventor-mit-edu.ezproxy.canberra.edu.au/explore/blogs/karen/2016/08/heart.html) to see if I could get the data to show live as it does here. And my goals is to see a graph like this one when i click on graph (https://www.arduino.cc/en/Tutorial/Genuino101CurieBLEHeartRateMonitor)

7

Does anyone have had any chance to review it? I think the issue is the type of data on arduino. Or do you have any idea of what datatype does the mit App inventor wants? I tried all the options ble has (bytes, float, integer, short)

8

You are sending your data with a print command, which sends text.

However, you used a Receive Bytes command to request Bytes, so the input arrives as a list of numbers that you have to look up in the ASII table to decode back into text.

If you send text, request text on the other end.

9

Thank you for the explenation. Which command does that?
I don't seem to find the correct one in this list (http://iot.appinventor.mit.edu.ezproxy.canberra.edu.au/#/bluetoothle/bluetoothleintro)
Do I have to get another extension to translate the value? Or should I chance to one of the type in here?(https://www.arduino.cc/reference/en/language/functions/communication/serial/print/)

10

Go back in this thread and read

Review how it sends and receives data.