Issue when reading and writing REAL numbers

[xtnctx]

So I've been working with Arduino Nano 33 BLE Sense and I'm using the ArduinoBLE library . I know that I can send an encoded string and parse it to my board, but I want to make it memory efficient and only send real numbers.

WRITE = flutter_blue; READ = ArduinoBLE

In my dart code, I have:

await my_characteristic?.write([1000]);

In my arduino board, I have:

BLECharacteristic my_characteristic(MY_UUID, BLERead | BLEWrite, sizeof(uint32_t));
uint32_t value = 0;

my_characteristic.readValue(value); // this will immediately store my value

After reading, value = 232 😕😕😕

I just noticed that it is sending a type of byte array to my board. So I have to convert my data before sending. P.S. I know the Endianness of my board after doing some test.

Uint8List integerToBytes(int value) {
    return Uint8List(4)..buffer.asByteData().setInt32(0, value, Endian.little);
  }

var data = integerToBytes(1000); // [232, 3, 0, 0]
await my_characteristic?.write(data); // Success! this is the real value that I want to send.

WRITE = ArduinoBLE ; READ = flutter_blue

Now the board is the sender:

my_characteristic.writeValue(1000);

Then I am reading the same byte array in my dart code, So I have to convert it vice versa:

num bytesToInteger(List<int> bytes) {
    /// Given
    /// 232 3 0 0

    /// Endian.little representation:
    /// To binary
    /// 00000000 00000000 00000011 11101000
    /// Combine
    /// 00000000000000000000001111101000

    /// Equivalent : 1000

    num value = 0;
    if (Endian.host == Endian.big) {
      bytes = List.from(bytes.reversed); //Forcing to be Endian.little (I think most of the devices nowadays uses this type)
    }
    for (var i = 0, length = bytes.length; i < length; i++) {
      value += bytes[i] * pow(256, i);
    }
    return value;
  }

var readValueArray = await my_characteristic?.read(); // [232, 3, 0, 0]
num readValue = bytesToInteger(readValueArray!); // 1000. Successful reading!

That is how I solved my problem. I hope there is a new version of flutter_blue to read and write real numbers based on this issue.

I just started using this package. Please let me know if I miss something.

[spekary]

This is not something flutter blue will ever do, nor any other bluetooth library. Its up to the developer to unpack data and know the format of the data.