Atmel AT91CAP9, User Manual

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AT91CAP9A-DK Development Kit User Guide 3-3
6321B–CAP–02-Jul-07
3.2 Clock Circuity
There are two on-board clock sources:
„ 24.576 MHz standard crystal for the AC97 audio interface
„ 50.000 MHz oscillator for the RMII Ethernet interface
3.3 Reset Circuity
The AT91CAP9A-DKZ mezzanine board generates the NRST signal for the whole system.
3.4 Shutdown Controller
The SHDN signal issued by the Reset Controller of the AT91CAP9 chip is provided by the AT91CAP9A-
DKZ mezzanine board and routed to the ATW connector, in order to control the power supply unit.
As explained in Section 2.4 “Powering Up the Board” on page 2-2 , the remote controlling of the power
supply can be bypassed with jumper J5.
3.5 Power Supply Circuity
The AT91CAP-DKM motherboard derives the necessary system voltages from the ATX supply.
On-board switching regulators provide the following voltage sources:
„ 1.2V
„ 1.8V
„ 2.5V
3.6 Memory
The only memory resource available on the AT91CAP-DKM motherboard is an Atmel serial EEPROM
(TWI bus connection).
System memory resources are to be connected directly to the AT91CAP9A-DKZ mezzanine via the
AT91CAP9-MEMxx extension boards.
3.7 Remote Communication
3.7.1 CAN Interface
The AT91CAP-DKM board features one serial CAN 2.0B communication port which is physically con-
nected to a J24 3-way screw-style connector.
An on-board standard 120-Ohm terminator is available. Simply install jumper J25 to enable termination.
3.7.2 Host USB Interface
A dual host connection (J26 = dual Type A socket) is available on the AT91CAP-DKM motherboard.