USB - Enable Multi-Packet Rx and Tx - #1009
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Jul 3, 2026
* Add 16KB buffer for USB option (1024 bytes per EP)
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Summary
As an improvement to #963, this PR fully enables the USB Peripheral's Multi-Packet Tx/Rx feature.
This allows for a speed up of mainly Bulk-Transfers (Getting approx 900KBps with a 64 packet size and 512 byte Endpoint buffer size - Up from 600KBps), whilst reducing the number of CPU interrupts from 13,000/sec to 1000/sec.
Tx Multi-Packet support is automatically enabled should the outgoing data size be greater than the USB Packet size.
Rx Multi-Packet support has to be manually enabled per endpoint with the new UsbBus's
configure_out_endpoint_multipacket_rxfunction. This is in order to keep default behaviour where any amount of data in an Rx Endpoint triggers a interrupt.Since endpoint allocation size is now calculated at compile time (Since #963), I have removed some logic that calculates this at runtime, since it is no longer required.
There is also a new
usb-buffer-16kfeature flag to the crate. This is for completion, allowing for up to a 1024 byte endpoint buffer.