Datasheet

PCA9698 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2010. All rights reserved.
Product data sheet Rev. 3 — 3 August 2010 16 of 48
NXP Semiconductors
PCA9698
40-bit Fm+ I
2
C-bus advanced I/O port with RESET, OE and INT
7.5 Device ID - PCA9698 ID field
The Device ID field is a 3 byte read-only (24 bits) word giving the following information:
• 12 bits with the manufacturer name, unique per manufacturer (e.g., NXP)
• 9 bits with the part identification, assigned by manufacturer (e.g., PCA9698)
• 3 bits with the die revision, assigned by manufacturer (e.g., RevX)
The Device ID is read-only, hard-wired in the device and can be accessed as follows:
1. START command
2. The master sends the Reserved Device ID I
2
C-bus address followed by the R/W bit
set to ‘0’ (write): ‘1111 1000’.
3. The master sends the I
2
C-bus slave address of the slave device it needs to identify.
The LSB is a ‘Don’t care’ value. Only one device must acknowledge this byte (the one
that has the I
2
C-bus slave address).
4. The master sends a Re-START command.
Remark: A STOP command followed by a START command will reset the slave state
machine and the Device ID Read cannot be performed. Also, a STOP command or a
Re-START command followed by an access to another slave device will reset the
slave state machine and the Device ID Read cannot be performed.
5. The master sends the Reserved Device ID I
2
C-bus address followed by the R/W bit
set to ‘1’ (read): ‘1111 1001’.
6. The Device ID Read can be done, starting with the 12 manufacturer bits (first byte +
4 MSBs of the second byte), followed by the 9 part identification bits (4 LSBs of the
second byte + 5 MSBs of the third byte), and then the 3 die revision bits (3 LSBs of
the third byte).
7. The master ends the reading sequence by NACKing the last byte, thus resetting the
slave device state machine and allowing the master to send the STOP command.
Remark: The reading of the Device ID can be stopped anytime by sending a NACK
command.
If the master continues to ACK the bytes after the third byte, the PCA9698 rolls back
to the first byte and keeps sending the Device ID sequence until a NACK has been
detected.
For the PCA9698, the Device ID is as shown in Figure 10
.
Fig 10. PCA9698 ID field
0
002aab94
2
0 0
00 0 0 0 0 0 0
00 0 0 0 0 0 0
revision
0
0 0 0 0
part identification
manufacturer