USBDevice: clearHalt() method
Limited availability
This feature is not Baseline because it does not work in some of the most widely-used browsers.
Experimental: This is an experimental technology
Check the Browser compatibility table carefully before using this in production.
Secure context: This feature is available only in secure contexts (HTTPS), in some or all supporting browsers.
Note: This feature is available in Web Workers.
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 transfer 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
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.
Examples
The following example shows how to test for and clear a 'stall' condition
in the result of a data transfer.
Note: What data can be passed to a USB device and how it is passed is particular and unique to each device.
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
| Specification |
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| WebUSB API # dom-usbdevice-clearhalt |
Browser compatibility
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clearHalt
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Legend
Tip: you can click/tap on a cell for more information.
- Full support
- Full support
- No support
- No support
- Experimental. Expect behavior to change in the future.