pca9674a NXP Semiconductors, pca9674a Datasheet - Page 12

• Manufacturer Part Number: pca9674a
• Description: Remote 8-bit I/o Expander For Fm+ I2c-bus With Interrupt
• Manufacturer: NXP Semiconductors

NXP Semiconductors
Product data sheet
PCA9674_PCA9674A_2
7.2.2 Device ID (PCA9674/74A ID field)
The Device ID field is a 3-byte read-only (24 bits) word giving the following information:
The Device ID is read-only, hardwired in the device and can be accessed as follows:
1. START command
2. The master sends the Reserved Device ID I
3. The master sends the I
4. The master sends a Re-START command.
5. The master sends the Reserved Device ID I
6. The device ID read can be done, starting with the 8 manufacturer bits (first byte +
7. The master ends the reading sequence by NACKing the last byte, thus resetting the
Fig 12. PCA9674/74A ID
•
•
•
8 bits with the manufacturer name, unique per manufacturer (for example, NXP).
13 bits with the part identification, assigned by manufacturer, the 7 MSBs with the
category ID and the 6 LSBs with the feature ID (for example, for example
PCA9674/74A 16-bit quasi-output I/O expander).
3 bits with the die revision, assigned by manufacturer (for example, Rev X).
bit set to 0 (write).
The LSB is a ‘Don’t care’ value. Only one device must acknowledge this byte (the one
that has the I
Remark: A STOP command followed by a START command will reset the slave state
machine and the Device ID read cannot be performed.
Remark: 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.
bit set to 1 (read).
4 MSB of the second byte), followed by the 13 part identification bits and then the
3 die revision bits (3 LSB of the third byte).
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.
Remark: If the master continues to ACK the bytes after the third byte, the
PCA9674/74A rolls back to the first byte and keeps sending the Device ID sequence
until a NACK has been detected.
For the PCA9674/74A, the Device ID is as shown in
part identification
2
C-bus slave address).
Rev. 02 — 12 October 2006
2
0
C-bus slave address of the slave device it needs to identify.
Remote 8-bit I/O expander for Fm+ I
0
category identification
manufacturer
0
0
0
0
0
2
2
C-bus address ‘1111 100’ with the R/W
C-bus address ‘1111 100’ with the R/W
0
1
0
0
Figure
feature identification
revision
0
0
PCA9674/74A
0
1
12.
0
0
0
2
C-bus with interrupt
002aac118
0
1
0
© NXP B.V. 2006. All rights reserved.
0
1
0
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