RE: question on zephyr usb hid

William.wei — Fri, 04 Aug 2023 05:45:55 GMT

Thanks haakonsh,

Yes, i forget this, i believe you are correct. let me try again.

Regards,

WIlliam.

RE: question on zephyr usb hid

haakonsh — Thu, 03 Aug 2023 19:54:53 GMT

Hey William,

wMaxPacketSize is set to 16 bytes, so your HID report is split into several packets. See the reported packets sizes in wireshark and compare with HID report size and you'll see that the totalt packet size is 28 bytes larger for 32, 64, and 128byte HID reports.

I guess there's a framing overhead of 28bytes when splitting the reports, so a 32byte HID report is split into 3 packets, each sent at 1ms intervals.

The USBD peripheral only supports a maximum of 64byte packet payloads btw.

BR,
Håkon Holdhus.