USB

USB Hub Class (+ TT)

An independent clean-room USB hub-class VIP: a hub with per-port state machines, separate status and CHANGE latches, a Status Change Endpoint bitmap and a Transaction Translator…

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shippingGroup USBStandard USB-IF Hub Class Specification (USB 2.0 ch.11, carried forward to 3.x)

Available now — real, tested verification collateral, not a roadmap placeholder.

Verification IP is not safety-rated. These are testbench components — no ASIL target, no FMEDA, no IP-XACT, no safety-mechanism interface. They exist to help you verify a design, not to carry a safety argument. The safety soft-IP catalog is over here.

The deliverable

What you get

Bus-functional model

An independent driver for the protocol, written clean-room from the public specification — not derived from our own RTL, so it is a genuine second source.

Passive protocol checker

A monitor that watches the bus and asserts the spec’s rules continuously, so a violation fails the run where it happens rather than downstream.

Self-checking interop testbench

A one-command testbench that drives the model against real RTL and hard-checks the result — reproduce every claim on day one.

An independent clean-room USB hub-class VIP: a hub with per-port state machines, separate status and CHANGE latches, a Status Change Endpoint bitmap and a Transaction Translator; a separately written host-side hub driver that polls, reads and acknowledges; and a passive checker (“usbhub/, make usbhub_oss, 22/22 checks). Six rules — power before connection, reset before enable, bitmap agrees with the change word, complete-split needs a start-split, over-current disables the port, and clear only what was reported — each pinned by a per-rule mask to its own injected fault. SCOPE: the hub class only. The USB packet layer beneath it is vip-usb2 (which ships against the real ip/usb2_dev), the SuperSpeed downstream link is vip-usb32, and electrical port-power switching is out. The sharpest result is a NEGATIVE one. A port’s STATUS is a level and its CHANGE is an edge; the host reads both together, then clears the change, and everything about a hub’s reliability lives in the gap between those two operations. T9 lands a disconnect inside that gap: a hub with a separate pending latch re-raises the change and the event survives, one without wipes it and the event is gone forever. The bus conversation is byte-identical either way — same GetPortStatus, same ClearPortFeature, same replies — so the checker is blind by construction, and both halves are asserted.

Key Features

Per-port state machine: power, connect, reset, enable, suspend, over-current
Separate status and CHANGE latches with a pending latch across the read/clear gap
Status Change Endpoint bitmap, and the class requests that read and clear it
Transaction Translator split transactions (SSPLIT / NYET / CSPLIT / ACK)
Passive checker, 6 rules, each pinned by a per-rule mask to its own injected fault
The lost-change-event blind spot named and asserted, not papered over

Standards & Compliance

USB-IF Hub Class Specification (USB 2.0 ch.11, carried forward to 3.x)

Pairs With

Built to lean against these catalog IPs during integration:

usb2_dev

Interested in the USB Hub Class (+ TT) VIP?

Deliverables, the file manifest, and licensing terms are shared under a mutual NDA.

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Verification IP is testbench collateral and is deliberately not safety-rated: no ASIL target, no FMEDA, and no IP-XACT descriptor. It carries no functional-safety claim.

circuit-design.space · +1-971-357-1400 · anovickis@circuit-design.space