Broadcasting data 60 FPS with GATT

[oishi89]

Hello. I'm using a CSR V.4 (csr8510 a10) and I'm trying to broadcast 40 bytes of data with 40 - 60 time per second. It seems to be possible and working fine but after sending data for a while I got a disconnection randomly with LIB USB ERROR message. I don't know how to figure out the throughput or bandwidth of CSR V.4. Do you have any ideal about that? Thanks

[zach-luman]

Hi @oishi89, How do you broadcast the data? Could you please upload the relevant code snippets?

[oishi89]

@zach-luman I was creating a timer with interval time is 16 ms.

[zach-luman]

In onSubscribe handler? @oishi89

[zach-luman]

Please upload the full characteristic code here.

[oishi89]

const bleno = require("bleno");

console.log("Starting bleno...");

const COUNTER_SERVICE_UUID = "00010000-9FAB-43C8-9231-40F6E305F96D"; const COUNTER_CHAR_UUID = "00010001-9FAB-43C8-9231-40F6E305F96D";

class CounterCharacteristic extends bleno.Characteristic { constructor() { super({ uuid: COUNTER_CHAR_UUID, properties: ["notify"], value: null });

    this.counter = 0;
}

onSubscribe(maxValueSize, updateValueCallback) {
    console.log(`Counter subscribed, max value size is ${maxValueSize}`);
    this.updateValueCallback = updateValueCallback;
}

onUnsubscribe() {
    console.log("Counter unsubscribed");
    this.updateValueCallback = null;
}    

sendNotification(value) {
    if(this.updateValueCallback) {
        console.log(`Sending notification with value ${value}`);

        const notificationBytes = new Buffer(4 * 10);

        for (var i = 0; i < 10; i++) {
                notificationBytes.writeFloatLE(value * 0.01, i * 4);        
        }

        this.updateValueCallback(notificationBytes);
    }
}

start() {
    console.log("Starting counter");
    this.handle = setInterval(() => {
        this.counter = (this.counter + 1) % 0xFFFF;
        this.sendNotification(this.counter);
    }, 16);
}

stop() {
    console.log("Stopping counter");
    clearInterval(this.handle);
    this.handle = null;
}

}

let counter = new CounterCharacteristic(); counter.start();

bleno.on("stateChange", state => {

if (state === "poweredOn") {

    bleno.startAdvertising("Counter", [COUNTER_SERVICE_UUID], err => {
        if (err) console.log(err);
    });

} else {
    console.log("Stopping...");
    counter.stop();
    bleno.stopAdvertising();
}        

});

bleno.on("advertisingStart", err => {

console.log("Configuring services...");

if(err) {
    console.error(err);
    return;
}

let service = new bleno.PrimaryService({
    uuid: COUNTER_CHAR_UUID,
    characteristics: [counter]
});

bleno.setServices([service], err => {
    if(err)
        console.log(err);
    else
        console.log("Services configured");
});

});

// some diagnostics bleno.on("stateChange", state => console.log(Bleno: Adapter changed state to ${state}));

bleno.on("advertisingStart", err => console.log("Bleno: advertisingStart")); bleno.on("advertisingStartError", err => console.log("Bleno: advertisingStartError")); bleno.on("advertisingStop", err => console.log("Bleno: advertisingStop"));

bleno.on("servicesSet", err => console.log("Bleno: servicesSet")); bleno.on("servicesSetError", err => console.log("Bleno: servicesSetError"));

bleno.on("accept", clientAddress => console.log(Bleno: accept ${clientAddress})); bleno.on("disconnect", clientAddress => console.log(Bleno: disconnect ${clientAddress}));

[zach-luman]

@oishi89 Thanks for uploading code snippet. But I'm wondering how did you let this peripheral subscribed? In other word, how is onSubscribe handler called?