Datasheet

PCA9530_3 © NXP B.V. 2009. All rights reserved.
Product data sheet Rev. 03 — 26 February 2009 4 of 24
NXP Semiconductors
PCA9530
2-bit I
2
C-bus LED dimmer
The last bit of the address byte defines the operation to be performed. When set to logic 1
a read is selected, while a logic 0 selects a write operation.
6.2 Control register
Following the successful acknowledgement of the slave address, the bus master will send
a byte to the PCA9530, which will be stored in the Control register.
The lowest 3 bits are used as a pointer to determine which register will be accessed.
If the Auto-Increment flag is set, the three low order bits of the Control register are
automatically incremented after a read or write. This allows the user to program the
registers sequentially. The contents of these bits will rollover to ‘000’ after the last register
is accessed.
When Auto-Increment flag is set (AI = 1) and a read sequence is initiated, the sequence
must start by reading a register different from the Input register (B2 B1 B0 0 0 0).
Only the 3 least significant bits are affected by the AI flag. Unused bits must be
programmed with zeroes.
6.2.1 Control register definition
Reset state: 00h
Fig 5. Control register
002aae500
0 0 0 AI 0 B2 B1 B0
register address
Auto-Increment flag
Table 3. Register summary
B2 B1 B0 Symbol Access Description
0 0 0 INPUT read only input register
0 0 1 PSC0 read/write frequency prescaler 0
0 1 0 PWM0 read/write PWM register 0
0 1 1 PSC1 read/write frequency prescaler 1
1 0 0 PWM1 read/write PWM register 1
1 0 1 LS0 read/write LED selector