CS4210 Datasheet, PDF (31/102 Pages) National Semiconductor (TI) – IEEE 1394 OHCI Controller

Operational Description (Continued)
3.9 SERIAL EEPROM
A serial EEPROM may be used to configure the CS4210. If
a serial EEPROM device is connected, the CS4210 detects
the pull-up resistor on the EEDATA pin (pin 5) and consid-
ers the EEPROM present. Immediately after RST# is deas-
serted, the serial EEPROM is scanned via EEDATA and
EECLK (pin 4). The CS4210 reads configuration informa-
tion from the first 34 bytes of the EEPROM.
If the presence of the serial EEPROM was not detected,
the CS4210 will not attempt to load configuration data via
the EEDATA/EECLK pins. It will instead allow software to
write to the guidHi and guidLo bit fields of the GUID regis-
ter once after each hardware reset (RST#).
3.9.1 Serial EEPROM Cyclic Redundancy Check
The serial EEPROM uses a Cyclical Redundancy Check
(CRC) to insure the data in the EEPROM is valid. If the
CRC check fails, the data from the EEPROM is not loaded
into the mapped registers listed in Table 3-11. The CRC1
and CRC2 values may be computed using the sample
code in Figure 3-1 "CRC1 and CRC2 Sample Code" on
page 32. This code accepts hexadecimal data from STDIN
and writes data plus CRC to STDOUT. As a check, this
code should produce the results as shown in Figure 3-1.
Table 3-11. Serial EEPROM Map
Offset
00h
01h
02h
03h
04h
05h
06h
07h
08h
09h
0Ah
0Bh
0Ch
0Dh
0Eh
0Fh
10h
11h
12h
13h
14h
15h
16h
17h
18h
19h
1Ah
1Bh
1Ch
1Dh
1Eh
1fh
20h
21h
Description
subsystem[7:0]
subsystem[15:8]
subsystem[23:16]
subsystem[31:24]
configROMheader[7:0]
configROMheader[15:8]
configROMheader[23:16]
configROMheader[31:24]
busOptions[7:0]
busOptions[15:8]
busOptions[23:16]
busOptions[31:24]
guidHi[7:0]
guidHi[15:8]
guidHi[23:16]
guidHi[31:24]
guidLo[7:0]
guidLo[15:8]
guidLo[23:16]
guidLo[31:24]
nscControl[7:0]
nscControl[15:8]
nscControl[23:16]
nscControl[31:24]
nscTxThrsh[7:0]
nscTxThrsh[15:8]
nscTxThrsh[23:16]
nscTxThrsh[31:24]
cmcControl[7:0]
cmcControl[15:8]
cmcControl[23:16]
cmcControl[31:24]
CRC1
CRC2
Revision 1.0
31
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