Motorola CPX8216TCPX8216T, CPX8000 manual Hot Swap Process, Hot Swap Control Status Register CSR

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System Architecture

Hot Swap Control Status Register (CSR)

The CPX8216 supports hot swap CompactPCI cards with the standard control status register defined by the PICMG Hot Swap Specification. The register is visible in PCI configuration space and provides hot swap control and status bits: INS and EXT. The INS signal is set when ENUM# is asserted by a board being inserted into the system. The EXT signal is asserted when ENUM# is asserted by an operator triggering the microswitch in the board handles. The host also uses these bits to acknowledge and de-assert ENUM#.

The Hot Swap Process

PICMG divided the complete hot swap process into physical, hardware and software connection processes. These processes are formally broken down further into a group of transitional states, which are illustrated in the following figure.

PH Y SIC AL			H AR D W A R E			SO FTW ARE
C O N N EC T IO N		CONNECTIO N STATES				CONNECTIO N
S T AT ES							STATES
P0	P1
	H 0			H 1	H 2
				H1F	S0	S1		S2	S3
								S2Q	S3Q

When inserting a board, it goes through all states from P0 to S3. Conversely, a board transitions from S3 to P0 before being extracted. During normal operation, no states are skipped. Extracting a board in a software connection state other than S0 is likely to disrupt software enough to crash the system, but the CompactPCI bus, from a purely electrical point of view, will not be disrupted enough to cause logic levels to be violated.

Certain states are overlapping. For example, when the board is fully seated (completed P1), but has not yet started the hardware connection process

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