Hi Sara

I tried this tutorial with platformIO and VS Code and version 3 of the above example and it doesn’t work. (VS code and PlatformIO updated to the last version).

( Error message: conversion from ‘std::__cxx11::string’ {aka ‘std::__cxx11::basic_string’} to non-scalar type ‘String’ requested )

When trying version 2 it works lika a dream…
Best regards
Anders Oleander
Sweden

String value = pLedCharacteristic->getValue();
change to
std::string value = pLedCharacteristic->getValue();

Good morning
I’m starting, how to read several values ​​from the ESP32 on the html page, for example the values ​​of a DHT11 temperature sensor
thanks in advance

I believe the led value is binary value not a string so you can’t do String value = … it’s not a string, hope that helps!

/private/var/folders/8h/by6_jkqs2yx2fw89mdxrkcvh0000gn/T/.arduinoIDE-unsaved2024924-70222-1oax92m.allt/sketch_oct24b/sketch_oct24b.ino: In member function ‘virtual void MyCharacteristicCallbacks::onWrite(BLECharacteristic*)’:
/private/var/folders/8h/by6_jkqs2yx2fw89mdxrkcvh0000gn/T/.arduinoIDE-unsaved2024924-70222-1oax92m.allt/sketch_oct24b/sketch_oct24b.ino:39:46: error: conversion from ‘std::__cxx11::string’ {aka ‘std::__cxx11::basic_string’} to non-scalar type ‘String’ requested
String value = pLedCharacteristic->getValue();
~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~

exit status 1

Compilation error: conversion from ‘std::__cxx11::string’ {aka ‘std::__cxx11::basic_string’} to non-scalar type ‘String’ requested

Any clues about it?

Thanks a lot for the tutorial. and the code.

function buffer_str(tex) {
var ArrBuf = new ArrayBuffer(tex.length);
var VerBuffer = new Uint8Array(ArrBuf);
for (var i=0, texLen=tex.length; i<texLen; i++) {
VerBuffer[i] = tex.charCodeAt(i);
}
return ArrBuf;
}

Change function writeOnCharacteristic: return characteristic.writeValue(buffer_str(value+”\n”))

function writeOnCharacteristic(value){
if (bleServer && bleServer.connected) {
bleServiceFound.getCharacteristic(ledCharacteristic)
.then(characteristic => {
console.log(“Found the LED characteristic: “, characteristic.uuid);
return characteristic.writeValue(buffer_str(value+”\n”))
})
.then(() => {
latestValueSent.innerHTML = value;
console.log(“Value written to LEDcharacteristic:”, value);
})
.catch(error => {
console.error(“Error writing to the LED characteristic: “, error);
});
} else {
console.error (“Bluetooth is not connected. Cannot write to characteristic.”)
window.alert(“Bluetooth is not connected. Cannot write to characteristic. \n Connect to BLE first!”)
}
}