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HMS30C7202N
2004 MagnaChip Semiconductor Ltd. All Rights Reserved. Version 1.1
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9.5.1
Block Diagram
(Device descriptor)
Configuration Rom
DEV
(Device Interface)
(Receive FIFO)
Endpoint 1
(Transmit FIFO)
Endpoint 2
AMBA Interface
SIE
(Serial Interface Engine)
USB Transceiver
DMAC request signal
Fast APB I/F
AUSBP
AUSBN
Figure 9-1 USB Block Diagram
The USB, Figure 9-2: USBD Block Diagram comprises the Serial Interface Engine (SIE) and Device Interface
(DEV). The SIE connects to the USB through a bus transceiver, and performs NRZI conversion, bit un-stuffing,
CRC checking, packet decoding and serial to parallel conversion of the incoming data stream. In outgoing
data, it does the reverse, that is, parallel to serial of outgoing data stream and packetizing the data, CRC
generation, bit stuffing and NRZI generation.
The DEV provides the interface between the SIE and the device's endpoint FIFO, ROM storing the device
descriptor. The DEV handles the USB protocol, interpreting the incoming tokens and packets and collecting
and sending the outgoing data packets and handshakes. The endpoints FIFO (RX, TX) give the information of
their status (full/ empty) to the AMBA interface and AMBA I/F enable the CPU to access the FIFO's status
register and the device descriptor stored in ROM. The AMBA interface generates a FIFO read/write strobe
without FIFO's errors, based on APB signal timing. In case of data transmitting through TX FIFO (when USB
generates an OUT token, AMBA I/F generates Interrupt to CPU), the user should set the transmitting enable
bit in the control register. If the error of FIFO (Rx: overrun, TX: under-run) occurs, the AMBA I/F cannot
generate FIFO read/ write.
9.5.2
Theory of Operation
The MagnaChip USB Core enables a designer to connect virtually any device requiring incoming or outgoing
PC data to the Universal Serial Bus. As illustrated in Figure 9-2: USBD Block Diagram, the USB core
comprises two parts, the SIE and DEV. The SIE connects to the Universal Serial Bus via a bus transceiver.
The interface between the SIE and the DEV is a byte-oriented interface that exchanges various types of data
packets between two blocks.
Serial Interface Engine
The SIE converts the bit-serial, NRZI encoded and bit-stuffed data stream of the USB into a byte and packet
oriented data stream required by the DEV. As shown in Figure 9-3: MagnaChip Serial Interface Engine, it
comprises seven blocks: Digital Phase Lock Loop, Input NRZI decode and bit-unstuff, Packet Decoder, Packet
Encoder, Output bit stuff and NRZI encode, Counters, and the CRC Generation & Checking block. Each of the
blocks is described in the following sections.