Kontron VSBC-32 - Manual (Page 53)

VSBC-32 Functional Description
ID 21168, Rev. 04 Page 2 - 21 © PEP Modular Computers GmbH
2.7 Frontpanel Functions
The frontpanel status indicators consist of three LED’s with the following functions:
• Yellow Watchdog LED
• Green General Purpose
• Red CPU Halt or Reset
The green LED is user-defined by the customer. It is set by the software during startup
when the MC68(EN)360 is initialized.
Figure 2-6: VSBC-32(E)
Frontpanel LED and
Button Locations
A Reset button is fitted to the front panel to avoid false operation. The Reset button trig-
gers the on-board system reset generator. In addition, an Abort button is also fitted to
the front panel. The Abort button generates a non-maskable level-7 interrupt which is
used for debugging purposes.
2.8 RTC and SRAM Data Retention
Short-term data retention for RTC and SRAM is gained with two Gold Caps, each with a
value of 0.22 Farad. In contrast to Lithium cells, Gold Caps do not require servicing.
This short-term backup is intended for short power failures or for reconfiguring systems.
An empty Gold Cap needs approximately three hours to charge up, with backup times
dependant on the temperature, memory size and memory manufacturer tolerances. A
well charged Gold Cap provides a minimum of 10 hours backup time.
Laboratory tests at PEP indicate a typical backup time of 1 week for both 256kB and
1MByte SRAM plus RTC (the typical on-board backup current is below 2µA). The
charge and discharge behaviour of Gold Caps is documented in the graphics overleaf.
For long-term data retention, 5V standby power supply could be provided via CXC
ST3A, pin 5 (user-defined line). This would require special wiring on the CXC backplane
or a special battery CXC module.
W U H
RST AB
Legend:
Yellow Watchdog LED
Green General Purpose
Red CPU Halt or Reset
RST Reset Button
AB Abort Button