Flash Memory, Direct Memory Access DMA, Timers

Direct Memory Access (DMA)	Functional Description

The MVME5500 board contains the following I2C serial devices:

z256 byte EEPROM for fixed GT-64260B initialization

z8KB EEPROM for VPD

z8KB EEPROM for user-defined VPD

z256 byte EEPROM for SPD

zDS1621 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.

2.6.5Direct 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.

2.6.6Timers

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-bitwatchdog 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.

2.7Flash 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.

MVME55006E Single-Board Computer Installation and Use (6806800A37D)