Philips Semiconductors

Product data sheet

PCA9552

2004 Oct 01

5

DEVICE ADDRESSING

Following a START condition the bus master must output the

address of the slave it is accessing. The address of the PCA9552 is

shown in Figure 4. To conserve power, no internal pull-up resistors

are incorporated on the hardware selectable address pins and they

must be pulled HIGH or LOW.

1

1

0

0

A2

A1

A0

SLAVE ADDRESS

su01420

FIXED

HARDWARE SELECTABLE

R/W

Figure 4. Slave address

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.

CONTROL REGISTER

Following the successful acknowledgement of the slave address,

the bus master will send a byte to the PCA9552 which will be stored

in the Control Register. This register can be read and written via the

0

0

AI

B2

B1

B0

0

SW00898

B3

AUTO-INCREMENT FLAG

REGISTER ADDRESS

RESET STATE: 00h

Figure 5. Control register

The lowest 3 bits are used as a pointer to determine which register

will be accessed.

If the auto-increment flag (AI) is set, the four 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 ‘0000’ 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

‘0’ (B3 B2 B1 B0

0 0 0 0 0).

Only the 4 least significant bits are affected by the AI flag.

Unused bits must be programmed with zeroes.

Control Register definition

B3

B2

B1

B0

REGISTER

NAME

TYPE

REGISTER

FUNCTION

0

0

0

0

INPUT0

READ

INPUT

REGISTER 0

0

0

0

1

INPUT1

READ

INPUT

REGISTER 1

0

0

1

0

PSC0

READ/

WRITE

FREQUENCY

PRESCALER 0

0

0

1

1

PWM0

READ/

WRITE

PWM

REGISTER 0

0

1

0

0

PSC1

READ/

WRITE

FREQUENCY

PRESCALER 1

0

1

0

1

PWM1

READ/

WRITE

PWM

REGISTER 1

0

1

1

0

LS0

READ/

WRITE

LED 0–3

SELECTOR

0

1

1

1

LS1

READ/

WRITE

LED 4–7

SELECTOR

1

0

0

0

LS2

READ/

WRITE

LED 8–11

SELECTOR

1

0

0

1

LS3

READ/

WRITE

LED 12–15

SELECTOR

REGISTER DESCRIPTION

INPUT0 — INPUT REGISTER 0

LED

7

LED

6

LED

5

LED

4

LED

3

LED

2

LED

1

LED

0

bit

7

6

5

4

3

2

1

0

default

X

X

X

X

X

X

X

X

The INPUT register 0 reflects the state of the device pins (inputs 0

to 7). Writes to this register will be acknowledged but will have no

effect.

NOTE: The default value “X” is determined by the externally applied

logic level, normally ‘1’ when used for directly driving LED with

INPUT1 — INPUT REGISTER 1

LED

15

LED

14

LED

13

LED

12

LED

11

LED

10

LED

9

LED

8

bit

7

6

5

4

3

2

1

0

default

X

X

X

X

X

X

X

X

The INPUT register 1 reflects the state of the device pins (inputs 8

to 15). Writes to this register will be acknowledged but will have no

effect.

NOTE: The default value “X” is determined by the externally applied

logic level, normally ‘1’ when used for directly driving LED with

PSC0 — FREQUENCY PRESCALER 0

bit

7

6

5

4

3

2

1

0

default

1

1

1

1

1

1

1

1

PSC0 is used to program the period of the PWM output.

The period of BLINK0

+

(PSC0

) 1)

44