ox16pci958 Oxford Electrical Products, ox16pci958 Datasheet - Page 31

• Manufacturer Part Number: ox16pci958
• Description: Octal Uart With Interface
• Manufacturer: Oxford Electrical Products

OXFORD SEMICONDUCTOR LTD.
5. EEPROM
5.1.
After the host bus RESET signal has been asserted and then released, the OX16PCI958 reads the
attached Microwire-type serial EEPROM to obtain configuration information. The EEPROM must be in
16-bit mode, and connected for 3-wire operation, as shown in Figure 2.
The EEPROM must be set up to provide 16-bit data, e.g. by tying the ORG pin high on an AT96C46.
Any serial EEPROM with a 16-bit data and Microwire-compatible read instruction, where the number
of address bits is either 6 or 8, should be suitable for use with the OX16PCI958. The EEPROM does
not have to have a sequential read feature. This means that most 93C46, 93C56 and 93C66 parts
should be suitable.
The interface timings are designed to be suitable for EEPROMs with maximum clock frequencies
down to 250 kHz. The EEPROM reader unit sets up EECS and EEDIO 70 PCI clock cycles before
generating a rising edge on EECK, and it samples EEDIO 70 PCI clock cycles after the EECK rising
edge. The EECK clock cycle lasts for 140 PCI clock cycles, giving an EEPROM clock rate of 238 kHz
when the PCI clock is running at 33
DS-0022 Nov 05
EEDIO
EECS
EECK
The EEPROM Reader
DO
OX16PCI958
DI
X
1
1
Figure 2 Example Circuit for EEPROM Connection
EEDIO
EECK
EECS
1
1
Figure 3 EEPROM Read Waveform
0
0
1
/
3
MHz.
A n
A n
External—Free Release
A n-
A n-
VDD
ORG
DI
DO
SK
CS
A 1
A 1
FM93C46A
A 0
A 0
EEPROM
0
0
D 15
D 15
OX16PCI958 DATA SHEET
D 1
D 1
D 0
D 0
X
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