Blink1 mk2 Chrome connectivity via WEBUSB API Light Blink Issue

Question

I am working on a project that need notification alert via browser using Blink(1) mk2 device. I have tried the following code for connection to the usb using WEBUSB API.

const VENDOR_ID = 0x27b8;
navigator.usb.requestDevice({
  filters: [{
    vendorId: VENDOR_ID
  }]
}).then(selectedDevice => {
  device = selectedDevice;
console.log("open")
 var tOpen = device.open();

console.log("opened")
return tOpen;
}).then(() => {
console.log("selectConfiguration")
  return device.selectConfiguration(1);
}).then(() => {
console.log("claimInterface")
  return device.claimInterface(0);
}).then(() => {
console.log("controlTransferOut")
 const r = Math.floor((Math.random() * 255) + 0);
  const g = Math.floor((Math.random() * 255) + 0);
  const b = Math.floor((Math.random() * 255) + 0);
  // not entirely sure what is going on below...
  const fadeMillis = 500;
  const th = (fadeMillis / 10) >> 8;
  const tl = (fadeMillis / 10) & 0xff;

  const data = new Uint8Array([0x01, 0x63, r, g, b, th, tl, 0x00, 0x00]).buffer;


var rgb = new Uint8Array(3);
  rgb[0] = r;
  rgb[1] = g;
  rgb[2] = b;

  return device.controlTransferOut({
    requestType: 'standard',
    recipient: 'interface', 
    request: 0x09,
    value: 1,
    index: 0
  },data);
}).then(result => {
  console.log(result);
}).catch(error => {
  console.log(error);
});

I am able to connect to usb after setting the permissions popup. After that above code opens it, selectConfiguration, claimInterface also worked fine and when I call controlTransferOut it also sends out the command and return the result as:

USBOutTransferResult {bytesWritten: 8, status: "ok"}

But blinking or color change on the USB does not reflected.

Am I missing something or is there any other configuration I need to use in order to get the light up on USB?

Answer 1

I ran this code myself and found that when I set requestType to "standard" I got a "stall" but if I set it to "class" (which is correct since this is the HID class control transfer SET_REPORT) then I get "ok" and the color of the LED on my blink(1) mk2 changes.

Note, the RGB values in your snippet above are set randomly so you may be getting a very dim color.