Artesyn MVME55006E Single Board Computer Installation and Use (July 2014) - Manual (Page 56)

Functional Description
MVME55006E Single Board Computer Installation and Use (6806800A37J) 56
2.11 Real Time Clock and NVRAM
The SGS-Thomson M48T37V is used by the MVME5500 board to provide 32KB of non-volatile
static RAM, real-time clock and watchdog timer. The watchdog timer, if enabled, can be
programmed to generate either an interrupt or system reset if it expires. Refer to the
MK48T37V Data Sheet for programming information.
The M48T37V consists of two parts:
 A 44-pin 330mil SOIC device that contains the RTC, the oscillator, 32KB of SRAM and gold-
plated sockets for the SNAPHAT battery.
 A SNAPHAT battery that houses the crystal and the battery.
The SNAPHAT battery package is mounted on top of the SOIC MT48T37V device after the
completion of the surface mount process. The battery housing is keyed to prevent reverse
insertion.
2.12 System Control and Status Registers
The MVME5500 CPU board contains System Control and Status Registers mapped into Bank 1
of the GT-64260B device bus interface. Refer for the MMVE5500 Single-Board Computer
Programmer’s Reference Guide for details.
2.13 Sources of Reset
The sources of reset on the MVME5500 are the following:
 Power-up
 Abort/Reset Switch
 NVRAM Watchdog Timer
 GT-64260B Watchdog Timer
 System Control register bit
 VME Bus Reset