GE CM6 Hardware Reference Manual page 59

Watchdog
nvSRAM Real Time Clock
GE Intelligent Platforms – CM6 Hardware Reference Manual, Fourth Edition
- cPCI clocks (CLK0...CLK6) are driven (outputs)
- PCI interrupts (INTA.D) are inputs and handled by the system
- the cPCI arbitration of the seven REQ/GNT is handled in the system board
Non-System mode:
- cPCI reset (RST#) is input
- cPCI clock (CLK0) is input
- board is a interrupt requester
- board request cPCI bus and must wait until the system board grant the bus
cPCI Bridge Vendor ID:
cPCI Bridge device ID:
The cPCI Bridge has a serial autoload EEPROM which loads at every power-
up standard register setting into the bridge. The content of the EEPROM differs
if the board is used either as system or non-system board. The boot-up program
can program the autoload EEPROM device with the correct content in
dependence of the current board position. If the content of the EEPROM must
be reprogramed the system has to be switched off/on afterwards to load the
changed register settings.
It is strongly recommended not to access this device under user software,
because irregular content may prevent the board to boot-up.
Please refer to the 'Attention' paragraph under 'Initial Inspection' in Chapter
2, Unpacking and Handling.
For security of application software, the CM6 offers a software controlled
hardware two stage watchdog with independent count values for each stage.
First stage generates a SMI. The second stage issuing a reset signal if its time-
out interval expires. The configurable granularity reaches from 256 ms to
16384 ms.
For more information please see the watchdog registers in section CPLD
Registers.
The CM6 provides the Simtek STK17TA8 which combines a 1 Mbit
nonvolatile static RAM with a full-featured real-time clock.
The SRAM can be read and written an unlimited number of times, while
independent, nonvolatile data resides in the nonvolatile elements. On each
power-up/power-down cycle the SRAM is automatically loaded from
respectively stored in the nvSRAM part of the chip.
The device provides unlimited load/recall operations but the STORE
operations are limited to 200k. STORE operation are always performed at
power-off cycle or activated by an address sequence.
The Real-Time Clock function provides an accurate clock with leap year
tracking and a programmable, high accuracy oscillator. The Alarm function is
programmable for one-time alarms or periodic seconds, minutes, hours, or
days. There is also a programmable Watchdog Timer for process control.
12D8h
E110h
Page 58