Android: usb.getDevices() succeeds but serial.getDevices() fails

[stewartoallen]

Chrome on Android supports navigator.usb but not navigator.serial so I'm trying to use this polyfill to access a serial device that works from Chrome on Mac & PC.

The command that succeeds in finding and connecting to the device on all platforms, including Android:

navigator.usb.requestDevice({
    filters:[{
        vendorId: 0x0403,
        productId: 0x6001
    }]
}).then(p => console.log({p}))

I would expect the following to work, but it does not:

exports.serial.requestPort({
    filters:[{
        usbVendorId: 0x0403,
        usbProductId: 0x6001
    }]
}).then(p => console.log({p}))

the same command replacing exports.serial with navigator.serial on Mac and Windows succeeds. getPorts() similarly fails

[stewartoallen]

turns out the device shows up as class 0, not class 2. not sure what to do with this knowledge because I know nothing about usb-serial. but that's the filter that prevented it from showing. the WebSerial implementations do handle this somehow. android, mac, windows all return the same info below.

[stewartoallen]

On PC, Mac, Android the device shows up as having only one interface which does not match the device class. So I presumed this could be used as both the transfer and control interface (seems this is anticipated in the code). I changed the serial.ts code to allow searching for devices with a different class code from the class code used later for interfaces. But then USBOutTransfer stalls trying to set line coding.

[reillyeon]

Device class 0 means "check the interface class" and interface class 255 means "vendor specific". This is an FTDI device which means it uses a vendor-specific USB serial protocol rather than the standard USB CDC-ACM protocol support by this polyfill. Issue #8 tracks adding support for FTDI chips.