Datasheet

Product data sheet Rev. 3 — 3 August 2010 17 of 48

NXP Semiconductors

PCA9698

40-bit Fm+ I

C-bus advanced I/O port with RESET, OE and INT

7.6 GPIO All Call

A ‘GPIO All Call’ command allows the programming of multiple advanced GPIOs with

different I

C-bus addresses at the same time. This allows to optimize code programming

when the master needs to send the same instruction to several devices. To respond to

such a command and sequence, the PCA9698 needs to have its IOAC bit (register 2Ah,

bit 3) set to 1. Devices that have this bit set to 0 do not participate in any ‘GPIO All Call’

sequence.

The ‘GPIO All Call’ command can be performed only for a write operation and cannot be

used in conjunction with a read operation.

• Master initiates a command sequence with the START command, the ‘GPIO All Call’

command associated with a Write command: Start − 1101 110 + Write

• All the devices that are programmed to respond to this command will acknowledge

• The master then sends the data and all the devices that are programmed to respond

acknowledge the byte(s)

• The master ends the sequence by sending a STOP or Repeated START command.

If the master initiates a ‘GPIO All Call’ sequence with a Read command, none of the slave

devices acknowledge.

7.7 Output state change on ACK or STOP

State change of the I/Os programmed as outputs can be done either:

• during the ACK phase every time an Output Port register is modified. The output state

is then updated one-by-one (at a bank level): OCH bit = 1 (register 2Ah, bit 1)

• at a STOP command allowing all the outputs to change at the exact same moment:

OCH bit = 0 (register 2Ah, bit 1).

Change of the outputs at the STOP command allows synchronizing of all the programmed

banks in a single device, and also allows synchronizing outputs of more than one

PCA9698.

Example 1: Only one PCA9698 is used on the I

C-bus and all the outputs need to change

at the same time.

• OCH bit (Mode Selection Register, bit 1) must be equal to ‘0’.

• The master accesses the device and programs the Output Port register(s) that has

(have) to be changed (up to 5 ports).

• When done, the master must generate a STOP command.

• At the STOP command, the PCA9698 will update the Output Port register(s) that has

(have) been programmed and change the output states all at the same time.

Example 2: More than one PCA9698 is used on the I

C-bus and all the outputs need to

change at the same time.

• OCH bit (Mode Selection Register, bit 1) must be equal to ‘0’ in all the devices.

• The master device must access the devices one-by-one.

• Access to each device must be separated by a Re-START command.