CAT24C208
www.onsemi.com
8
Arbitration
The device performs a simplistic arbitration between the
DDC and DSP ports. While the arbitration scheme described
is not foolproof, it does prevent most errors.
Arbitration logic within the device monitors activity on
DDC_SCL and DSP_SCL. When both I
2
C ports are idle,
DDC_SCL and DSP_SCL are both high and the arbitration
logic is inactive. When a START condition is detected on
either port, the opposite port SCL line is pulled low, holding
off activity on that port. When the initiating SCL line has
remained high for one full second, the arbitration logic
assumes that the initiating devices is finished and releases
the other SCL line. If the non−initiating device has been
waiting for access, it can now read or write the device.
Table 9. CONFIGURATION REGISTER
Register Function
MSB LSB
7 6 5 4 3 2 1 0
Configuration Register X X X X WE AB1 AB0 NB
Function Description
NB: Number of memory banks in DDC port memory map. 0 = 2 Banks, 1 = 1 Bank
AB0: Active Bank Control Bit 0 (See Table 10)
AB1: Active Bank Control Bit 1 (See Table 10)
WE DDC: Write Enable 0 = Write Disabled, 1= Write Enabled (Note 8)
8. WE affects only write operations from the DDC port, not the display port. The display port always has write access.
Table 10. CONFIGURATION REGISTER TRUTH TABLE
AB1 AB0 NB EDID Select Pin Active Bank
0 X 0 0 Lower Bank
0 X 0 1 Upper Bank
1 0 0 X Lower Bank
1 1 0 X Upper Bank
X X 1 X Lower (only) Bank
The configuration register is a non−volatile register and is available from either DSP or DDC port at address 62h / 63h for
write and read resp.
Table 11. READ CONFIGURATION REGISTER
START 0110 0011 ACK DATA NO ACK STOP
Table 12. WRITE CONFIGURATION REGISTER
START 0110 0010 ACK DUMMY ADDRESS ACK XXXX WE AB1 AB0 NB ACK STOP
ORDERING INFORMATION
Device Order Number
Specific
Device
Marking
Package
Type
Temperature Range
Lead
Finish
Shipping
†
CAT24C208WI−GT3 24C208WI SOIC−8 Industrial NiPdAu Tape & Reel, 3,000 Units / Reel
†For information on tape and reel specifications, including part orientation and tape sizes, please refer to our Tape and Reel Packaging
Specifications Brochure, BRD8011/D.
9. All packages are RoHS−compliant (Lead−free, Halogen−free).
10.The standard lead finish is NiPdAu.
11. For information on tape and reel specifications, including part orientation and tape sizes, please refer to our Tape and Reel Packaging
Specifications Brochure, BRD8011/D.
ON Semiconductor is licensed by the Philips Corporation to carry the I
2
C bus protocol.
