pcm16c00 National Semiconductor Corporation, pcm16c00 Datasheet - Page 20

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pcm16c00

Manufacturer Part Number
pcm16c00
Description
Configurable Multiple Function Pcmcia Interface Chip
Manufacturer
National Semiconductor Corporation
Datasheet
6 0 Operational Modes
6 4 FUNCTIONAL CONCURRENCY
A Dual Function Card may be designed using the
PCM16C00 IC that allows both functions to run concurrent-
ly The PCM16C00 bus arbitration unit interrupt unit and
common memory unit allow functions to take control of the
local data bus on the card at their discretion The bus arbiter
will arbitrate between the PCMCIA Host Function 0 and
Function 1 Once granted the bus each function may gain
access to the common memory address space One tech-
nique is to tie each function’s Memory Write signal to the
PCM16C00
TRI-STATE its Memory Write if not granted the bus The
PCM16C00 then generates MEMWEH
for memory access Also each function may tie its Memory
Read to the Common Memory devices (tied to PCM16C00
MEMOE ) Again each device should TRI-STATE its Mem-
ory Read signal when it is not granted the bus The
PCM16C00 will TRI-STATE its MEMOE
PCMCIA Host has not been granted the bus Note that both
MEMWR
PCM16C00 to prevent glitching
As mentioned before once the PCMCIA Host has been
granted access to the card bus the steering of transactions
to function 0 or function 1 is implicit in the Address and the
I O Window decoder settings for the PCM16C00 If Func-
tion 0 or 1 has been granted the Card local bus and a
PCMCIA host attempts an I O transaction (i e - Host is de-
nied bus) the PCM16C00 will assert the HWAIT
extend the cycle de-assert the INPACK
the Rdy Bsy bit in the Pin Replacement Registers
6 5 16-BIT 8-BIT OPERATION
During normal operation the PCM16C00 will function as a
16-bit device If a LAN IC is used the LAN should always be
configured as a 16-bit device If 8-bit operation is desired
(PCMCIA Host accesses are 8-bit) the PCM16C00 will pass
the 8-bit transaction to the Function In the case of a 16-bit
LAN device the PCM16C00 will pass the 8-bit transaction
since the LAN IC register access is 8 bits With the common
memory device the PCM16C00 will check the Memls8 bit in
the Pin Polarity Register If Memls8 is clear (16-bit memory)
the PCM16C00 will strobe MEMWEL
even address boundaries and MEMWEH
es on odd address boundaries A 16-bit access causes both
MEMWEL
device will still execute 16-bit accesses to the Common
memory even though PCMCIA is using 8-bit accesses Due
to this a MEMWR
MEMWEL
local DMA with Common Memory If the LAN uses remote
DMA and places 16 bits of data from the Common Memory
into the PCM16C00 for subsequent transferral to PCMCIA it
will implement bus steering on PCMCIA 8-bit transactions to
this data and delay issuing RACK
device until both bytes of data are read from the I O Regis-
ter If Memls8 is set (8-bit memory) the PCM16C00 will
strobe MEMWEL
even
PCM16C00 will only obtain one byte of data by strobing
MEMWEL
address
and MEMOE
to be strobed This allows the LAN to use 16-bit
and MEMWEL
MEMWR
boundaries
for 8-bit PCMCIA accesses on odd or
will cause both MEMWEH
input
have pull-up resistors on the
to be strobed A 16-bit LAN
For
Each
or WACK
16-bit
(Continued)
for 8-bit accesses on
function
and MEMWEL
for 8-bit access-
signal and set
access
to the LAN
when the
signal to
should
and
the
20
6 6 SPECIAL TESTABILITY MODES
National Proprietary TEST(2 0) pins should be left discon-
nected
Software
System or device software can interact with the PCM16C00
IC directly using either the PCM16C00’s PCMCIA registers
PCMCIA Extended registers or PCM16C00 specific regis-
ters
CIS (CARD INFORMATION STRUCTURE)
When the PCM16C00 powers on the contents of the
EEPROM are loaded into the device’s shadow RAM This
not only allows attribute memory accesses to the CIS but it
also provides defaults for 10 PCM16C00 specific registers
to be loaded This allows default loading of parameters that
are transparent to system or device software The best use
is for the card manufacturer to determine what values these
should be and program them into the EEPROM when the
CIS is programmed Either system software such as Card
Services Socket Services or device software may read and
parse the CIS by accessing attribute memory on the PC
Card If desired this software agent may write to the CIS or
default EEPROM registers and if desired have these new
values saved to the EEPROM The actual contents of the
CIS and the static registers is PC Card design dependent
PCMCIA REGISTERS
There are two sets of standard PCMCIA Registers which
includes the optional I O Event Register This allows each
function’s client software to be able to configure control
and get status for its respective function For a detailed de-
scription see the register specifications in this document
PCMCIA EXTENDED REGISTERS
Each function has a set of base and limit registers The
value placed in these registers by system software controls
the I O Addressing window for each function
PCM16C00 SPECIFIC REGISTERS
There are three categories of PCM16C00 specific registers
The first set of registers are those specific registers that are
automatically loaded from the EEPROM and should be
transparent to system software Even though software
could be written to modify these registers the most likely
scenario would be the case where software performed mac-
ro time scale power management using the PMGR and
Clock Register for software power management The sec-
ond set are those registers not stored in the EEPROM (such
as the ID Register and EEPROM Control Register) These
may be accessed by system software as desired using the
attribute memory space The third set are only accessible
when in LAN Mode This includes the Data I O Miscellane-
ous and Reset Register for use with the LAN Adapter
These registers are mapped to the I O Memory space with-
in the I O address window for function 0 These registers
should be accessed by a LAN client device driver for the
appropriate LAN device and Network Operating System

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