rtd cpuModule CME37786HX, User Manual

Page: 25 / 122

CME37786HX RTD Embedded Technologies, Inc.
17
Connecting to the PC/104-Plus PCI Bus
The cpuModule is simply plugged onto a PC/104 stack. Other PC/104- Plus boards may then con-
nect to the cpuModule’s PC/104- Plus bus connector. Supplying power to the PCI bus is provided
by the cpuModule.
We recommend you follow the procedure described for the PC/104 bus.
There are three additional considerations when using the PCI bus; PCI Bus signaling level, the slot
selection switches on add in boards, and 3.3 volt power source for the expansion cards.
PCI Bus Signaling Levels
The PCI bus can operate at 3.3 or 5 volt signaling levels. This is controlled by solder blob jumper
B1 and is configured at the factory for 3.3 volts from on board. If you desire to use 5 volt signaling,
because you are connecting cards to the bus that require 5 volt signaling, you have to change the sol-
der blob jumper B1. See
Jumpers and Solder Jumper Settings on page 100 for details.
Slot Selection Switches
Unlike PC/104 cards, PC/104 Plus expansion cards have a “slot” selection switch or jumpers. In
total, there are 4 PCI cards that can be stacked onto the cpuModule with switch positions 0 through
3. The distance from the CPU determines these switch settings. The card closest to the CPU is said
to be in slot 0, the next closest slot 1 and so on to the final card as slot 3.
The “slot” setting method may vary from manufacturer to manufacturer, but the concept is the same.
The CPU is designed to provide the correct delay to the clock signals to compensate for the bus
length. The correct switch setting ensures the proper clock delay setting, interrupt assignment, and
bus grant/request channel assignment. Refer to the expansion board’s manual for the proper settings.
Each expansion card must be in a different slot.
WARNING! The bus can only operate as 3.3 Volt signaling OR 5 volt
signaling, not both. You will have to ensure that all your ex-
pansion card can operate together at a single signaling level.
NOTE! This requirement means that all PC/104 Plus cards must be
stacked either on the top or the bottom of the CPU, not on
both sides.