OXCF950_06 Datasheet, PDF (53/66 Pages) Oxford Semiconductor – low cost asynchronous 16-bit PC card or Compact Flash UART device

OXFORD SEMICONDUCTOR, INC.
OXCF950 rev B DATA SHEET
7 SERIAL EEPROM SPECIFICATION
The OXCF950 can be configured using an optional serial
electrically-erasable programmable read only memory
(EEPROM). If the EEPROM is not present, the device will
remain in its default configuration after reset. Although this
may be adequate for some applications, many will benefit
from the degree of programmability afforded by this
feature. The EEPROM also allows accesses to the
integrated UART, which can be useful for default setups.
The EEPROM interface supports a variety of serial
EEPROM devices that have a proprietary serial interface
known as Microwire^TM. This interface has four pins which
supply the memory device with a clock, a chip-select, and
serial data input and output lines. In order to read from
such a device, a controller has to output serially a read
command and address, then input serially the data. The
interface controller has been designed to handle (auto
detect) the following list of compatible devices that have a
16-bit data word format but differ in memory size (and
hence the number of address bits). NM93C46 (64
WORDS), NM93C56 (128 WORDS), devices with 256
WORDS, 512 WORDs and 1024 WORDS.
The OXCF950 incorporates a controller module which
reads data from the serial EEPROM and writes data into
the relevant register space. It performs this operation in a
sequence which starts immediately after a CF/PCMCIA
reset and ends either when the controller finds no
EEPROM is present or when it reaches the end of the
eeprom data.
Following device configuration, driver software can access
the serial EEPROM through four bits in the device-specific
Local Configuration Register ESC[4:1]. Software can use
this register to manipulate the device pins in order to read
and modify the EEPROM contents as desired.
A Windows® based utility to program the EEPROM is
available. For further details please contact your local
distributor.
Microwire^TM is a trade mark of National Semiconductor. For
a description of Microwire^TM, please refer to National
Semiconductor data manuals.
7.1 EEPROM data Organisation
The serial EEPROM data is divided into 4 zones. The size
of each zone is an exact multiple of 16-bit WORDs. Zone 0
is allocated to the header. An EEPROM program must
contain a valid header before any further data is
interrogated. The EEPROM can be programmed from the
CF/PCMCIA Interface.. The general EEPROM data
structure is shown in Table 41.
Note the zone information is not stored 0,1,2,3 but as
shown in the table (0, 2, 1, 3).
DATA Zone
0
2
1
3
7.2 Zone 0: Header
Size (WORDS)
One
One or more
Two or more
Multiples of two
Description
Header
Local Configuration registers
CIS Configuration
Function Access
Table 41: EEPROM Data Format
The zone header identifies the EEPROM program as valid, and is the first value to be read and is at address 0 in the EEPROM.
It has the following format:
DS-0027 Feb 06
External—Free Release
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