Which microcontroller for USB HOST for HID devices?

[nockieboy]

You can supply external clock.

But also, with the micro USB connector, you would need an adapter cable to connect external devices.

Yeah, it's just an extra thing to sort out though - no real issue, just glad you mentioned it otherwise I might have missed that in the small print in the datasheet!   I'm probably going to use a micro USB connector on the final board anyway if I'm going to use two - there isn't room for more than one full-size USB connector, so adapter cables will be necessary. (I ordered one with the Itsybitsy).

[mikeselectricstuff]

PIC24 (from memory 24FJ64GB002)  can do USB host without a crystal. Available in 28 pin DIP,SO,SSOP and QFN

[ataradov]

PIC24 (from memory 24FJ64GB002)  can do USB host without a crystal. Available in 28 pin DIP,SO,SSOP and QFN

This is questionable. The datasheet is vague, but I don't see how it is possible.

It has "FRC Accuracy @ 8 MHz" typical +/-0.25 % (min -1.25%, max +1 %). So already strange. 8 MHz would have to be multiplied to 48 MHz to eventually get 12 MHz, so the final accuracy would be worse.

But even if we assume +/-0.25%, it is still not enough to operate a compliant host. USB spec requires +/-0.05% accuracy for hosts.

It would probably work in practice at room temperature, especially for HID devices. But will definitely violate the spec.

[Berni]

Even if it doesn't have a crystal you can probably bodge one on there.

As for when it is integrated onto the real PCB you don't need a crystal if you already have a FPGA on there. Just make the FPGA output the correct clock frequency on a pin and wire that straight into the crystal input pin.

[nockieboy]

Okay, so it looks like I'm going with the SAMD21 MCU for this application.  I'm testing with an Itsybitsy M0 Express currently, just waiting on a USB OTG adapter cable to test a keyboard, but I'm getting events from the USB port, so it's looking good so far.

Thanks everyone.