Show BLE Input (ESP32C3) on a Label. Thats it

MIT App Inventor Help
1

I am not realy interested in Apps, its just a small Park for a project, so learning Android Studio is not an Option, which lead me to NoCode Apps, but i can't get it done here either. I only found one tutorial on youtube, which lead me so far. (see below) I get everything connected and it looks fine, but how do i get my bytes into a float or what ever, to display it, as what it is: a Weight (Kg in my case).

Any help or direction? All tutorials i find seem to be outdated?

#include <Adafruit_SSD1306.h>
#include <Wire.h>
#include <Adafruit_GFX.h>
#include <BLEDevice.h>
#include <BLEServer.h>
#include <BLEUtils.h>
#include <BLE2902.h>
#include <BLE2901.h>
#include "HX711.h"

// Display
#define SCREEN_WIDTH 128
#define SCREEN_HEIGHT 64
#define calibration_factor 21910.0

// HX711 Pins
#define LOADCELL_DOUT_PIN 3
#define LOADCELL_SCK_PIN 4

// BLE
BLEServer *pServer = NULL;
BLECharacteristic *pCharacteristic = NULL;
bool deviceConnected = false;
bool oldDeviceConnected = false;

// UUIDs
#define SERVICE_UUID "4fafc201-1fb5-459e-8fcc-c5c9c331914b"
#define CHARACTERISTIC_UUID "beb5483e-36e1-4688-b7f5-ea07361b26a8"

// Display object
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, -1);

// Weight-related variables
float highestValue = 0.0;
HX711 scale;

class MyServerCallbacks : public BLEServerCallbacks {
  void onConnect(BLEServer *pServer) {
    deviceConnected = true;
  };

  void onDisconnect(BLEServer *pServer) {
    deviceConnected = false;
  }
};

void setup() {
  Serial.begin(115200);

  // Initialize HX711
  scale.begin(LOADCELL_DOUT_PIN, LOADCELL_SCK_PIN);
  scale.set_scale(calibration_factor);
  scale.tare();

  // Initialize BLE
  BLEDevice::init("ESP32");
  pServer = BLEDevice::createServer();
  pServer->setCallbacks(new MyServerCallbacks());

  BLEService *pService = pServer->createService(SERVICE_UUID);

  pCharacteristic = pService->createCharacteristic(
    CHARACTERISTIC_UUID,
    BLECharacteristic::PROPERTY_READ | BLECharacteristic::PROPERTY_NOTIFY
  );

  pCharacteristic->addDescriptor(new BLE2902());
  pService->start();

  BLEAdvertising *pAdvertising = BLEDevice::getAdvertising();
  pAdvertising->addServiceUUID(SERVICE_UUID);
  pAdvertising->setScanResponse(false);
  BLEDevice::startAdvertising();
  Serial.println("Waiting for a client to connect...");

  // Initialize Display
  if (!display.begin(SSD1306_SWITCHCAPVCC, 0x3C)) {
    Serial.println(F("SSD1306 not found!"));
    for (;;);
  }
  display.clearDisplay();
  display.setTextSize(2.5);
  display.setTextColor(SSD1306_WHITE);
}
void loop() {
  // Reading from the scale
  float currentValue = scale.get_units(1);
  if (currentValue > highestValue) {
    highestValue = currentValue;
  }

  // Display values
  display.clearDisplay();
 display.setCursor(70, 10);  // Textposition (x, y)
  display.print("Max:");

  // Aktuellen Wert anzeigen
  display.setCursor(70, 30);
  display.print(highestValue, 1);  // Zwei Nachkommastellen

  display.setCursor(0, 10);  // Textposition (x, y)
  display.print("Now:");

  // Aktuellen Wert anzeigen
  display.setCursor(0, 30);
  display.print(currentValue, 1);  // Zwei Nachkommastellen


  // Inhalt auf dem Display aktualisieren
  display.display();

  // Send the highest value via BLE
  if (deviceConnected) {
    pCharacteristic->setValue(highestValue);
    pCharacteristic->notify();
  }

  // Handle reconnection
  if (!deviceConnected && oldDeviceConnected) {
    delay(500);
    pServer->startAdvertising();
    oldDeviceConnected = deviceConnected;
  }

  // Handle new connection
  if (deviceConnected && !oldDeviceConnected) {
    oldDeviceConnected = deviceConnected;
  }

  delay(50);
}

https://i.ibb.co/MMwtGJP/mit.jpg

2

(Canned Reply: ABG- Export & Upload .aia)
Export your .aia file and upload it here.

export_and_upload_aia

.

..

3

Help.aia (201.3 KB)

Currently going through the search results, but can't find anything usefull for me.
By this times, probably learning some basic coding would have been the easier way. :sweat_smile:

4

From your sketch, you are feeding a float directly to BLE without any text conversion.

But in your app, you Register for Strings
and try to treat the received data as text.

blocks (1)
blocks (1)1176×542 73.3 KB

blocks
blocks1192×596 76.6 KB

You have two options:

  • Find the sketch command to turn that float into text, and send the text, or
  • switch to Register for Floats and When BLE Floats Received on the app side.

Don't mix the two options.

6

i'll try "the switch to Register for Floats and When BLE Floats Received on the app side", it just might take me a few days :grin:

This works:

works
works1417×384 39.6 KB

phew...there a lot to learn for me on the app side. Guess i'll dive into some tutorials during this winter. Thanks for you very valuable input, Stranger!