Filter
Top Products
Philips Semiconductors
ISP1521
Hi-Speed USB hub controller
Product data Rev. 03 — 24 November 2004 10 of 53
9397 750 13702
© Koninklijke Philips Electronics N.V. 2004. All rights reserved.
8. Functional description
8.1 Analog transceivers
The integrated transceivers directly interface to USB lines. They can transmit and
receive serial data at high-speed (480 Mbit/s), full-speed (12 Mbit/s) and low-speed
(1.5 Mbit/s).
8.2 Hub controller core
The main components of the hub core are:
• Philips Serial Interface Engine (SIE)
• Routing logic
• Transaction Translator (TT)
• Mini-host controller
• Hub repeater
• Hub controller
• Port controller
• Bit clock recovery.
8.2.1 Philips serial interface engine
The Philips SIE implements the full USB protocol layer. It is completely hardwired for
speed and needs no firmware intervention. The functions of this block include:
synchronization, pattern recognition, parallel or serial conversion, bit (de-)stuffing,
CRC checking and generation, Packet IDentifier verification and generation, address
recognition, and handshake evaluation and generation.
8.2.2 Routing logic
The routing logic directs signaling to the appropriate modules (mini-host controller,
Original USB repeater and Hi-Speed USB repeater) according to the topology in
which the hub is placed.
8.2.3 Transaction translator
The TT acts as a go-between mechanism that links devices operating in the Original
USB mode and the Hi-Speed USB upstream mode. For the ‘IN’ direction, data is
concatenated in TT buffers till the proper length is reached, before the host takes the
transaction. In the reverse direction (OUT), the mini-host dispenses the data
contained in TT buffers over a period that fits into the Original USB bandwidth. This
continues until all outgoing data is emptied. TT buffers are used only on split
transactions.
8.2.4 Mini-host controller
The internal mini-host generates all the Original USB IN, OUT or SETUP tokens for
the downstream facing ports, while the upstream facing port is in the high-speed
mode. The responses from the Original USB devices are collected in TT buffers, until
the end of the complete split transaction clears the TT buffers.