USBDevice.clearHalt()

The clearHalt() method of the USBDevice interface returns a promise that resolves when a halt condition is cleared. A halt condition is when a data tranfer to or from the device has a status of 'stall', which requires the web page (the host system, in USB terminology) to clear that condition. See the for details.

Syntax

var promise = USBDevice.clearHalt(direction, endpointNumber)

Parameters

direction

Indicates whether the devices input or output should be cleared. Valid values are 'in' or 'out'.

endpointNumber

Indicates the number of the endpoint to clear. The promise will reject if an invalid endpoint is supplied.

Return value

A promise.

Example

The following example shows how to test for and clear a 'stall' condition in the result of a data transfer.

while (true) {
  let result = await data.transferIn(1, 6);

  if (result.data && result.data.byteLength === 6) {
    console.log('Channel 1: ' + result.data.getUint16(0));
    console.log('Channel 2: ' + result.data.getUint16(2));
    console.log('Channel 5: ' + result.data.getUint16(4));
  }

  if (result.status === 'stall') {
    console.warn('Endpoint stalled. Clearing.');
    await device.clearHalt('in', 1);
  }
}

Specifications

Browser compatibility