Motorola CPCI-6115 - Manual (Page 112)

CPCI-6115 CompactPCI Single Board Computer Installation and Use (6806800A68D)
Transition Module Preparation and Installation PMC I/O Connector
110
The 80mm is “cut out of the middle” of the PMC I/O module. This means that features in the
front half of the module keep their positioning relative to the front edge of the board while
features in the back half of the board keep their positioning relative to the back edge of the
board.
5.7.9 PMC I/O Connector
The mapping used by the CPCI-6115 SBC of the PMC I/O connectors onto the CompactPCI
user I/O connectors is reversed by the CPCI-6115-MCPTM. This allows the designer of a PMC
to create a PMC I/O module without knowledge of how the CPCI-6115 SBC maps signals
through the backplane. There is nothing to tie the PMC I/O module to the CPCI-6115 SBC
platform and in this sense the module is “universal”.
5.7.10 Host I/O Connector
The second connector on the PMC I/O module is used to provide power and ground to the
module. In addition, the remaining pins may be used for host I/O signals. Any host I/O
functionality for which there is no space available, or which the cost of does not justify its
presence on the standard board, may be implemented in a “host I/O module”. This functionality
is special to the host (in this case the CPCI-6115 SBC) and so the host I/O module is not a
“universal” module. However, if the host I/O connector pinout is reused on future transition
modules, the host I/O module may be reused.
If possible, optional host I/O routed to the host I/O connector will be terminated in such a fashion
that the host does not incorrectly determine that a device is connected to that I/O when no
module is present. This termination must not interfere with normal operation of the I/O when a
module is present.
5.7.11 PMC I/O Module Presence Detection and Identification
Presence detection and identification of PMC I/O modules is currently an open issue. It is
anticipated that PMCs and PMC I/O modules will be designed as pairs. Any and all of the 64
bits of PMC user I/O are available to the designers to use as they wish to detect and identify an
installed PMC I/O module. No standard exists, or is likely to exist, so hopefully the method
chosen will be sufficiently robust to prevent accidental misidentification of modules.
Host I/O modules also need to be detected and identified. To this end the I2C bus provided from
the CPCI-6115 SBC is connected to both PMC I/O module sites. The addresses and content of
the I2C devices to reside on the Host I/O module remain an open issue.