Functional Description
MEN Mikro Elektronik GmbH
24
20A014-00 E2 – 2007-08-16
2
Functional Description
The following describes the individual functions of the board and their
configuration on the board. There is no detailed description of the individual
controller chips and the CPU. They can be obtained from the data sheets or data
books of the semiconductor manufacturer concerned (
Chapter 6.1 Literature and
Web Resources on page 118
).
2.1
Power Supply
The board is supplied with +5 V and ±12 V via the VMEbus. However, ±12 V may
be required only by some mezzanine modules. The plug-on CPU card itself is
supplied via PCI-104 connectors J1/J2.
The on-board power supply generates the 1.2 V core voltage for the CPU, 2.5 V for
memory and the 1.5 V core voltage for the FPGA.
2.1.1
Watchdog
A voltage monitor supervises 5 V, 3.3 V, 2.5 V and 1.2 V and holds the CPU in reset
condition until all supply voltages are within their nominal values. In addition this
device contains a watchdog that must be triggered. The watchdog timeout switches
automatically from 56 s after reset to 1.6 s after the first trigger pulse. This allows a
longer watchdog timeout period during the start-up phase.
After power-up the CPU loads the FPGA. The configuration file depends on the
application. After configuration the FPGA serves the external hardware watchdog
without further action by the CPU. If there is any problem loading the FPGA, the
external watchdog causes a reset.
An additional watchdog is implemented in the FPGA.
See also
Chapter 4.6.6.5 Hardware Monitor Support – Parameter psrXXX on page
112
.
2.2
Clock Supply
The CPU is supplied with one copy of the on-board PCI clocks. This is internally
multiplied to generate the core clock and the memory clock.
By default the A14C runs at 33 MHz (PCI), 132 MHz (SDRAM) and 792 MHz
(core).
2.3
Real-Time Clock
The board includes an RA8581 real-time clock. Interrupt generation of the RTC is
not supported. For data retention during power off the RTC is backed up by a
GoldCap capacitor. The GoldCap gives an autonomy of approx. two days when
fully loaded.
A control flag indicates a back-up power fail condition. In this case the contents of
the RTC cannot be expected to be valid. A message will be displayed on the
MENMON console in this case.
