Hotswap
CP690
Page 4 - 6
© 2002 PEP Modular Computers GmbH
ID 20955, Rev. 03
4.2
Design Implementation on CP690
4.2.1
Power Ramping
On the CP690, a special hotswap controller is used to ramp up the supply voltage of the PMC
modules (Back End Power). This is done to avoid transients on the 3.3V and the 5V power sup-
plies from the Hotswap system. When the power supply is stable, the hotswap controller gen-
erates a reset on the PMC slots to put the devices into a definite state.
4.2.2
Precharge
Precharge is provided on the CP690 by a resistor on each signal line (PCI bus), connected to
a 1V reference voltage.
4.2.3
Handle Switch
A microswitch is situated in the extractor handle. Opening the handle initiates the generation
of the ENUM interrupt (produced by the onboard logic).
4.2.4
ENUM# Interrupt
The onboard logic generates a low active interrupt signal to indicate that the board is about to
be extracted from the system or inserted into the system.
4.2.5
Hotswap Control and Status Register / Statemachine
All hotswap peripheral boards provide a Hotswap Control And Status Register which provides
information on the current state of the board. The defined bits in this register set are named, as
follows:
Due to the fact that no 64-bit transparent PCI-to-PCI bridge currently exists, which would pro-
vide built-in hotswap status registers, another way of implementing these bits had to be found.
The solution, therefore, is to put this information into the onboard logic.
Since on-chip registers handle read and write accesses in the same way, it is necessary to ex-
ercise care when configuring the PCI-to-PCI GPIOs (general purpose IOs).
Table 4-1: Hotswap Control and Status Register / Statemachine
Bit Name
Function
EXT
Indication of extraction process
INS
Indication of insertion process
LOO
Led on
EIM
ENUM mask bit
