IBM42S10SNNAA20 IBM42S12SNYAA20 IBM42S10LNYAA20
IBM42S10SNYAA20 IBM42S10LNNAA20 IBM42S12LNYAA20
1063/1250MBd Gigabit Interface Converter
Serial Module Definition Protocol (Serial ID)
The GBIC-1063NS, GBIC-1063NS-LW, GBIC-
1250NS, and GBIC-1250NS-LW have identifying
information stored in a Serial ID EEPROM. To read
the serial data from the serial ID module, the follow-
ing must occur (refer to Serial ID Figures 1, 2, and 3
throughout these steps):
3. Receive an acknowledge signal.
One zero bit is the acknowledge signal.
4. Send the address of the first byte to read.
The most significant bit of the address byte is
the first bit and is ignored.
1. Send a start sequence to the module.
5. Receive an acknowledge signal.
6. Send a start command.
This is done by changing the data line from high
to low while the clock is high.
7. Send the read data sequence.
2. Send the set data address sequence.
The read data sequence is 10100001. This
sequence will allow the user to begin reading
the data.
The set data address sequence is 10100000.
This sequence will allow the user to set the
memory address to start reading from.
8. Receive an acknowledge signal.
9. Read a data word.
Note: Be sure to toggle the data line only when
the clock is low. Toggling the data line while the
clock is high indicates a start or stop condition.
10. Send an acknowledge signal to receive the next
data word or send a stop command to stop
receiving data.
A stop command is given by toggling the data
from low to high while the clock is high.
Serial ID Figure 1 Start and Stop Timing
The critical timings for communicating to the serial
ID EEPROM are shown in Serial ID Figure 4 on
page 11.
SDA
SCL
For more information on the Serial ID protocol, see
Serial ID Data and Descriptions on page 22.
START
STOP
Serial ID Figure 2 Set Data Address Sequence Timing
Acknowledge from GBIC
This bit does not matter.
Acknowledge from GBIC
SDA
A
A
C
K
C
1
1
0
2
1
0
0
0
0
0
K
X
0
0
0
0
0
0
0
SCL
0
1
0
1
1
1
2
1
3
1
4
1
5
1
6
1
7
1
8
1
9
2
0
3
4
5
6
7
8
9
S
T
A
R
T
S
T
A
R
T
Data address to start reading
data from. (Addr. 0 in this
example, 0 through 127 available)
Byte entered to allow the
user to set the starting
address for a Serial ID data read.
GBIC.03
January 18, 2001
©IBM Corporation. All rights reserved.
Use is further subject to the provisions at the end of this document.
Page 10 of 34
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