PCMCIA Interface
10-24
GMS30C7201 Data Sheet
A total of 256 Mbytes address range is allocated for each PCMCIA Card. (So, there is
no need for an address window as an ISA based PCMCIA card controller is used to
access a total 64 Mbyte with very small system address range.) For the fast access
support of Mixed I/O and Memory Card, each region has 64M byte address range.
Also, the IOIS16 signal is not used.
External Buffer Requirement:
The external buffer must operate in both 3.3v and 5.0v to support low power cards.
CaDRV
and
CbDRV
control the External buffer to pass the correct signals to the
socket. LCX16244 is the 5V tolerant Buffer which has the enable pin. The data buffer
must be bidirectional. This bidirectional port can be easily controlled with an additional
control pin. LCX16245 is the 5V tolerant buffer which has an enable pin and a direction
control pin. The PCMCIAOutLEn can be used for direction control pin of the LCX16245.
Controller Pad Requirement:
Pads must tolerate 5v input from 5v PCMCIA Card.
Note
10.3.2 Interrupt handling
Interrupt handling is the most important role in the PCMCIA Host Bus Controller.
Interrupts are generated from two different sources, the Card Status change interrupt
and a Card-generated interrupt which requires host
’
s attention, e.g, data transmission
buffer is full, so, it
’
s requires some read operation from the host. Today, PCMCIA Cards
can generate level mode or pulse mode interrupts. A different mechanism is required
for Card status change interrupt handling. This interrupt source is monitored and
change status is saved in relevant registers, the Interface Status Register and Card
Status Change Register. Card Status Change includes the insertion or removal of the
card, battery warning or dead, and so on. Only Level mode interrupt is used in this type
of interrupt source. Each interrupt can be masked by setting the corresponding bit of
the Card Status Interrupt Configuration Register. The host can know the exact interrupt
source by reading the Interface Status Register and Card Status Change Register.
10.3.3 Enhanced power management
Three power down operations are mode supported for enhanced power management.
Most power is saved by disabling the clock to inactive blocks. Power down is entered
under software control.
Table 10-34: Power Down Modes
provides a summary.
Address Range
Function Area
0 - 64 Mbyte
Attribute Memory Area
64 - 128 Mbyte
Common Memory Area
64 - 192 Mbyte
I/O Area
192 - 256 Mbyte
Reserved for future use
Table 10-33: Address ranges and function areas
Mode
Summary
Partial Power Down
Interrupts still operate (to monitor card changes).
Full Power Down
All internal control logic disabled.