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Functional Description
4
and initialize any number of internal registers. In the second function, the
controller is used by the system software to read the contents of the VPD
EEPROM contained on the MVME5500 board, along with the SPD
EEPROM(s), to further initialize the memory controller and other
interfaces.
The MVME5500 board contains the following I2C serial devices:
❏
256 byte EEPROM for fixed GT-64260B initialization
❏
8KB EEPROM for VPD
❏
8KB EEPROM for user-defined VPD
❏
256 byte EEPROM for SPD
❏
DS1621 temperature sensor
The 8KB EEPROM devices are implemented using Atmel AT24C64
devices. These devices use two byte addressing to address the 8KB of the
device.
Direct Memory Access (DMA)
The GT-64260B has an 8-channel DMA controller integrated in the device.
Each DMA channel is capable of moving data between any source and any
destination. This controller can be programmed to move up to 16MB of
data per transaction. The GT-64260B DMA channels also support chained
mode of operation. For additional details regarding the GT-64260B DMA
capability, refer to the GT-64260B System Controller for PowerPC
Processors Data Sheet, listed in
Appendix D, Related Documentation
Timers
The GT-64260B supplies eight 32-bit counters/timers, each of which can
be programmed to operate as a counter or a timer. The timing reference is
based on the GT-64260B Tclk input, which is set at 133 MHz. Each
counter/timer is capable of generating an interrupt.
The GT-64260B also has an internal 32-bit watchdog timer that can be
configured to generate an NMI or a board reset. After the watchdog timer
is enabled, it becomes a free running counter that must be serviced