6-102203-1 Datasheet PCA9671PW,118, PCA9671BS,118, 6-102203-1 | P10-P12

Product data sheet Rev. 3 — 29 September 2011 10 of 33

NXP Semiconductors

PCA9671

Remote 16-bit I/O expander for Fm+ I

C-bus with reset

7.2.2 Device ID (PCA9671 ID field)

The Device ID field is a 3-byte read-only (24 bits) word giving the following information:

• 8 bits with the manufacturer name, unique per manufacturer (for example,

NXP Semiconductors).

• 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, PCA9671 16-bit

quasi-output I/O expander).

• 3 bits with the die revision, assigned by manufacturer (for example, Rev X).

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

C-bus address ‘1111 100’ with the R/W

bit set to logic 0 (write).

3. The master sends the I

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

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.

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.

5. The master sends the Reserved Device ID I

C-bus address ‘1111 100’ with the R/W

bit set to logic 1 (read).

6. The device ID read can be done, starting with the 8 manufacturer bits (first byte +

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).

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.

Remark: If the master continues to ACK the bytes after the third byte, the PCA9671

rolls back to the first byte and keeps sending the Device ID sequence until a NACK

has been detected.

For the PCA9671, the Device ID is as shown in Figure 11

Product data sheet Rev. 3 — 29 September 2011 11 of 33

NXP Semiconductors

PCA9671

Remote 16-bit I/O expander for Fm+ I

C-bus with reset

Fig 11. PCA9671 ID

If more than 2 bytes are read, the slave device loops back to the first byte (manufacturer byte) and

keeps sending data until the master generates a ‘no acknowledge’.

Fig 12. Device ID field reading

002aac249

0 0revision

0 1 0 1 0 1 00part identification

0 0 0 0 0 0 0

0 0 0 0

manufacturer

category identification feature identification

002aac335

1 1 1 1 0 0 0 AS 1

device ID address

START condition R/W

acknowledge from one

or several slave(s)

A5 A4 A3 A2 A1 A0 XA6 A 1 1 1 1 0 0 11

device ID address

C-bus slave address of

the device to be identified

don't care

acknowledge from

slave to be identified

acknowledge from

slave to be identified

R/W

M6 M5 M4M7 M2 M1 M0M3 A

acknowledge

from master

C5 C4 C3C6 C1 C0 F5C2 A

acknowledge

from master

manufacturer name

= 00000000

P3 P2 P1F4 P0 R2 R1 R0

revision = 000

feature identification

= 010100

A P

STOP

condition

no acknowledge

from master

category identification

= 0000001

Product data sheet Rev. 3 — 29 September 2011 12 of 33

NXP Semiconductors

PCA9671

Remote 16-bit I/O expander for Fm+ I

C-bus with reset

8. I/O programming

8.1 Quasi-bidirectional I/O architecture

The PCA9671’s 16 ports (see Figure 2) are entirely independent and can be used either

as input or output ports. Input data is transferred from the ports to the microcontroller in

the Read mode (see Figure 15

). Output data is transmitted to the ports in the Write mode

(see Figure 14

Every data transmission from the PCA9671 must consist of an even number of bytes, the

first byte will be referred to as P07 to P00, and the second byte as P17 to P10. The third

will be referred to as P07 to P00, and so on.

This quasi-bidirectional I/O can be used as an input or output without the use of a control

signal for data directions. At power-on the I/Os are HIGH. In this mode only a current

source (I

) to V

is active. An additional strong pull-up to V

trt(pu)

) allows fast rising

edges into heavily loaded outputs. These devices turn on when an output is written HIGH,

and are switched off by the negative edge of SCL. The I/Os should be HIGH before being

used as inputs. After power-on, as all the I/Os are set HIGH, all of them can be used as

inputs. Any change in setting of the I/Os as either inputs or outputs can be done with the

write mode.

Remark: If a HIGH is applied to an I/O which has been written earlier to LOW, a large

current (I

) will flow to V

8.2 Writing to the port (Output mode)

To write, the master (microcontroller) first addresses the slave device. By setting the last

bit of the byte containing the slave address to logic 0 the Write mode is entered. The

PCA9671 acknowledges and the master sends the first data byte for P07 to P00. After the

first data byte is acknowledged by the PCA9671, the second data byte P17 to P10 is sent

by the master. Once again, the PCA9671 acknowledges the receipt of the data. Each 8-bit

data is presented on the port lines after it has been acknowledged by the PCA9671.

The number of data bytes that can be sent successively is not limited. After every two

bytes, the previous data is overwritten.

The first data byte in every pair refers to Port 0 (P07 to P00), whereas the second data

byte in every pair refers to Port 1 (P17 to P10). See Figure 13

Fig 13. Correlation between bits and ports

002aab634

06 05 04 03 02 01 00

first byte

P06 P05 P04 P03 P02 P01 P00P07

A16 15 14 13 12 11 10

second byte

P16 P15 P14 P13 P12 P11 P10P17

P1-P3 P4-P6 P7-P9 P10-P12 P13-P15 P16-P18 P19-P21 P22-P24 P25-P27 P28-P30 P31-P33

6-102203-1

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