Preparing the Board
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1-13
1
IP Bus Strobe (J19)
Some IP bus implementations make use of the Strobe
∗
signal (pin AA19
on the Petra ASIC) as an input to the IP modules from the Petra IP2 sector.
Other IP interfaces require that the strobe be disconnected.
With a jumper installed between J19 pins 1-2, a programmable frequency
source is connected to the Strobe
∗
signal on the IP bus (for details, refer to
the Petra/IP2 chip programming model in the Programmer’s Reference
Guide).
If the jumper is removed from J19, the strobe line is available for a
sideband type of messaging between IP modules. The Strobe
∗
signal is not
connected to any active devices on the board, but it may be connected to a
pull-up resistor.
SRAM Backup Power Source (J22)
Header J22 determines the source for onboard static RAM backup power.
The MVME172P4 is factory-configured to use 5V standby
voltage as a backup power source for the SRAM (i.e., jumpers are installed
across pins 1-3 and 2-4). To select the onboard battery as the backup
power source, install the jumpers across pins 3-5 and 4-6.
Note
For MVME172P4s without the optional VMEbus interface (i.e.,
without the VMEchip2 ASIC), you must select the onboard
battery as the backup power source.
2
1
J19
IP Strobe disconnected
2
1
(Factory configuration)
J19
IP Strobe connected
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