cl-ps6700 Cirrus Logic, Inc., cl-ps6700 Datasheet - Page 18

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

3. FUNCTIONAL DESCRIPTION
The CL-PS7111 communicates with the CL-PS6700 through the memory bus. This bus has a special mul-
tiplexed mode that uses 16 bits of the data bus to transfer address and data messages to the CL-PS6700.
This split transaction bus supports posting a (single) read transaction so that the potentially long access
time of a PC Card does not disrupt the memory bus. The protocol defines two clocks to transmit address
messages, and one or two clocks for data messages. This allows efficient transfer of 32-bit words, as well
as bytes and half words.
3.1 PC Card (PCMCIA) Interface
3.1.1 PC Card Types
The supported PC Card v2.01 card types are:
Each card can be 3.3 V or 5 V, and power to each card is managed independently by the CL-PS7111 and
the corresponding CL-PS6700. General-purpose digital I/O (PCM_VS pins on the CL-PS6700) can be
used by the CPU to detect the voltage requirements of a card before applying power.
3.1.2 PC Card Address/Data Bus
The PC Card supports a 26-bit address bus and a 16-bit data bus. The CL-PS7111 multiplexes these
buses into a single 16-bit bus MD[15:0]. This bus is demultiplexed by the CL-PS6700, which also imple-
ments the low-level interface to the PC Card and provides voltage translation for mixed-voltage systems.
The CL-PS6700 also provides data buffering, endian conversion, and interrupt control for the PC Card.
Transfers between the CL-PS7111 and the CL-PS6700 are one or four bytes.
The CL-PS7111 accesses the CL-PS6700 as a memory-mapped peripheral on the memory bus. A chip
enable signal, PCE_L of CL-PS6700, is connected to CS[4] (and CS[5] for a second PC Card socket) from
the CL-PS7111.
3.1.3 PC Card Address Spaces and DMA
The PC Card standard defines three address spaces for PC Cards: memory space, I/O space, and
attribute space. Each of these is 64 Mbytes, requiring 26 address bits, while other command bits select
the space to be accessed.
Attribute memory space contains setup information such as the CIS. Attribute memory is accessed as an
8-bit device, but only at half-word boundaries (even bytes only).
Memory and I/O space for a card can each be 8 or 16 bits in width. The width of the access made to each
of these spaces by the CL-PS6700 is software configurable. In addition, I/O space accesses can be sized
dynamically by the PCM_WP (IOIS16_L) input.
All three address spaces for each card are mapped into the CL-PS7111 memory map and are directly
accessible by the CPU. In addition to these three address spaces, a card can contain a DMA target. The
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Memory-only card, such as flash or SRAM
I/O card, such as a modem card
Multifunction cards with both I/O and memory
DMA-capable cards
FUNCTIONAL DESCRIPTION
C
I R R U S
L
O G I C
C
O N F I D E N T I A L
, N D A R
PRELIMINARY DATA BOOK v1.0
E Q U I R E D
Low-Power PC Card Controller
November 1997
CL-PS6700