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Direct Memory Access (DMA) Functional Description
MVME55006E Single-Board Computer Installation and Use (6806800A37D)
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The MVME5500 board contains the following I2C serial devices:
z 256 byte EEPROM for fixed GT-64260B initialization
z 8KB EEPROM for VPD
z 8KB EEPROM for user-defined VPD
z 256 byte EEPROM for SPD
z 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.
2.6.5 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 C, Related Documentation.
2.6.6 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 periodically to keep it from expiring. Following reset, the watchdog timer
is disabled.
The watchdog timer has two output pins, WDNMI and WDE. The WDNMI is asserted after the
timer is enabled and the 24-bit NMI_VAL count is reached. The WDNMI pin is connected to one
of the GT-64260B interrupt input pins so that an interrupt is generated when the NMI_VAL
count is reached. The WDE pin is asserted after the watchdog timer is enabled and the 32-bit
watchdog count expires. The WDE pin is connected to the board reset logic so that a board
reset is generated when WDE is asserted. For additional details, refer to the GT-64260B
System Controller for PowerPC Processors Data Sheet, listed in Appendix C, Related
Documentation.
2.7 Flash Memory
The MVME5500 contains two banks of Flash memory accessed via the device controller
contained within the GT-64260B. The standard MVME5500 product is built with the 128Mb
devices.