Datasheet

3−18
3.8.5 Suspend Mode
The SUSPEND signal, provided for backward compatibility, gates the PRST (PCI reset) signal and the GRST (global
reset) signal from the controller. Besides gating PRST
and GRST, SUSPEND also gates PCLK inside the controller
in order to minimize power consumption.
It should also be noted that asynchronous signals, such as card status change interrupts and RI_OUT
, can be passed
to the host system without a PCI clock. However, if card status change interrupts are routed over the serial interrupt
stream, then the PCI clock must be restarted in order to pass the interrupt, because neither the internal oscillator nor
an external clock is routed to the serial-interrupt state machine. Figure 3−15 is a signal diagram of the suspend
function.
RESET
GNT
SUSPEND
PCLK
RESETIN
SUSPENDIN
PCLKIN
External Terminals
Internal Signals
Figure 3−15. Signal Diagram of Suspend Function
3.8.6 Requirements for Suspend Mode
The suspend mode prevents the clearing of all register contents on the assertion of reset (PRST or GRST) which
would require the reconfiguration of the controller by software. Asserting the SUSPEND
signal places the PCI outputs
of the controller in a high-impedance state and gates the PCLK signal internally to the controller unless a PCI
transaction is currently in process (GNT
is asserted). It is important that the PCI bus not be parked on the controller
when SUSPEND
is asserted, because the outputs are in a high-impedance state.
The GPIOs, MFUNC signals, and RI_OUT
signal are all active during SUSPEND, unless they are disabled in the
appropriate registers.