bleno cant send 256 bytes on dynamic read and notify

When i try to send 256 bytes using dynamic read or notification using bleno, the other end (Android or noble) receives only 22 bytes. See code below.

However, when 256 bytes are sent using a static readonly characteristic, all 256 bytes are received properly.

The BLE spec says characteristic values can be 512 bytes.

Is this a bug?

Environment: bleno: Macbook pro with Mavericks. Node v0.10.24 noble: Ubuntu 13 desktop with Node v0.10.24 android: API 19, Nexus 4

var chars = [];
for(var i = 0; i < 256; i++) {
    chars.push('a');
}

var StaticReadOnlyCharacteristic = function() {
    StaticReadOnlyCharacteristic.super_.call(this, {
        uuid: 'fffffffffffffffffffffffffffffff1',
        properties: ['read'],
        value: new Buffer(chars.join('')),
        descriptors: [
            new Descriptor({
                uuid: '2901',
                value: 'user description'
            })
        ]
    });
};
util.inherits(StaticReadOnlyCharacteristic, Characteristic);

var DynamicReadOnlyCharacteristic = function() {
    DynamicReadOnlyCharacteristic.super_.call(this, {
        uuid: 'fffffffffffffffffffffffffffffff2',
        properties: ['read']
    });
};

util.inherits(DynamicReadOnlyCharacteristic, Characteristic);

DynamicReadOnlyCharacteristic.prototype.onReadRequest = function(offset, callback) {
    console.log("on -> readRequest");
    var result = this.RESULT_SUCCESS;
    var data = new Buffer(chars.join(''));

    if (offset > data.length) {
        result = this.RESULT_INVALID_OFFSET;
        data = null;
    }

    callback(result, data);
};

[sandeepmistry]

MTU negotiation is handled by CoreBluetooth/blued on OS X, it’s always 23 from what I’ve seen. We’re stuck with this for unless Apple makes some changes.

Looks like CoreBluetooth/blued doesn’t handle long read characteristics. Typically, if the read response is the MTU size, the central would do another read with an offset to check if there is remaining data. I can look at having a bleno.mtu property or passing the MTU as an argument to the onReadRequest callback - but I don’t think either will help you. What stack are you using for your central?

[sandeepmistry]

@aravindanr closing for now, please re-open if you have more info.