MP3 NG: A Next Generation Consumer Platform
XAPP169 (v1.0) November 24, 1999 www.xilinx.com 11
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National Semiconductor USBN9602 USB Function ControllerThe USB interface in the design is based on a National Semiconduct or USBN9602 controller.
This device, packaged in a 28-pin SOIC package, supports full speed USB function controller
operation and includes an integrated USB transceiver. It contains seven endpoint FIFOs, two of
which are 64 bytes deep.
Figure 12 shows a block diagram of this device. The complete data sheet for the USBN9602
can be found at the following URL:
http://www.national.com/ds/US/USBN9602.pdf
The system interface for the USBN9602 is a simple 8-bit microproce ssor bus that can be
configured to operate in a multiplexed or non-multiplexed mode. The multiplexed mode is more
attractive from a software perspective since it supports random access to the device s’ internal
registers. This mode also reduces the number of interface pins required . For both of these
reasons this was chosen for this application. Figure 13 shows read timing for th e USBN9602
when operating in multiplexed mode.
Physical Layer Interface (PHY)
Media Access Controller (MAC)
Transceiver
48 MHz
Oscillator
Clock
Generator
XIN
XOUT
CLKOUT
Microcontroller Interface
D+ D- Upstream Port
INTR
V3.3
CS RD WR A0/ALE D[7:0]/AD[7:0]
EP2
Endpoint0
EP1
EP6EP5
RX
TX
Endpoint/Control FIFOs
VReg AGND
RESET
Vcc
GND
MODE[1:0]
StatusControl
SIE
USB Event
Detect
Clock
Recovery
EP4EP3
Figure 12: USBN9602 Block Diagram
(Courtesy National Semiconductor)