cl-ps6700 Cirrus Logic, Inc., cl-ps6700 Datasheet - Page 19

• Manufacturer Part Number: cl-ps6700
• Description: Low-power Pc Card Controller For The Cl-ps7111
• Manufacturer: Cirrus Logic, Inc.

CL-PS6700
Low-Power PC Card Controller
CL-PS7111 does not implement a DMA controller for the PC Card, but the CPU can emulate DMA cycles
by appropriately configuring the CL-PS6700, then accessing card I/O space (see
Table 4.4.2 on page
27).
In this case, the CL-PS6700 accesses the card using a newly defined DMA cycle (IORD/WR strobes used
with -REG high).
The PC Card standard requires all cards to follow the little-endian memory model. The CL-PS7111 can
support both the little-endian and big-endian modes of operation. Thus, the CL-PS6700 provides for
endian conversion, which is software configurable.
3.1.4 Byte Assembly/Disassembly and Queueing
Since all spaces on the cards (even I/O cards) are memory mapped, the CL-PS7111 can access the cards
directly. The CL-PS6700 can be programmed to assemble/disassemble the CL-PS7111 transfers to the
width of the PC Card. The CL-PS6700 has read and write buffers, allowing posting of both reads and
writes. The read queue is single entry, and the write FIFO can queue up to four CL-PS7111 transactions
(up to 16 bytes). Reads do not bypass queued writes (card transactions are processed in order).
Certain card access timing parameters are programmable and can be set to operate faster than the PC
Card specification allows. The CL-PS6700 contains a watchdog timer that ensures that a card access is
aborted if it exceeds a preprogrammed time limit, generating an interrupt to the CL-PS7111.
3.1.5 Card Configuration
After power-on or reset, a PC Card defaults to a memory-only card. The CPU then reads the card’s CIS
to determine the card type, access time, and so on, configuring the CL-PS6700 to properly access the
card.
Each PC Card’s V
and V
pins are individually controlled by its corresponding CL-PS6700 pins. The
CC
PP
CL-PS7111 controls the power to a card by writing to the CL-PS6700 registers. The CL-PS6700 ensures
that its signals to the sockets are in the proper state before applying and removing power to the sockets.
3.1.6 Hot Insertion Support
PC Cards are often used like floppies: The user can insert or remove cards while system power is on.
Typically, the CPU only applies power to a PC Card socket after it has detected a properly inserted card
and removes the power before the card is removed (that is, when the CPU detects that card lock is deas-
serted). Since each card is isolated from the system by its CL-PS6700, insertion and removal of cards
should not cause glitches on the system buses.
C
L
C
, N D A R
I R R U S
O G I C
O N F I D E N T I A L
E Q U I R E D
19
November 1997
PRELIMINARY DATA BOOK v1.0
FUNCTIONAL DESCRIPTION