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CL-PS6700-VC-A

Low-Power PC Card Controller for the CL-PS7111

Cirrus Logic 

CL-PS6700

Low-Power PC Card Controller

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:

q Memory-only card, such as flash or SRAM

q I/O card, such as a modem card

q Multifunction cards with both I/O and memory

q DMA-capable cards

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

CIRRUS LOGIC CONFIDENTIAL, NDA REQUIRED

18

FUNCTIONAL DESCRIPTION

November 1997

PRELIMINARY DATA BOOK v1.0

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