PCA9552_5

© Koninklijke Philips Electronics N.V. 2006. All rights reserved.

Product data sheet

Rev. 05 — 9 March 2006

14 of 28

Philips Semiconductors

PCA9552

8.2 Programming example

The following example will show how to set LED0 to LED3 on. It will then set LED4 and

LED5 to blink at 1 Hz at a 50 % duty cycle. LED6 and LED7 will be set to blink at 4 Hz and

at a 25 % duty cycle. LED8 to LED15 will be set to off.

Fig 15. High value resistor in parallel with

the LED

Fig 16. Device supplied by a lower voltage

002aac189

LED

LEDn

100 k

Ω

002aac190

LED

LEDn

3.3 V

5 V

Table 11:

Programming PCA9552

Program sequence

START

S

PCA9552 address with A0 to A2 = LOW

C0h

PSC0 subaddress + Auto-Increment

12h

Set prescaler PSC0 to achieve a period of 1 second:

PSC0 = 43

2Bh

Set PWM0 duty cycle to 50 %:

PWM0 = 128

80h

Set prescaler PCS1 to achieve a period of 0.25 seconds:

PSC1 = 10

0Ah

Set PWM1 output duty cycle to 25 %:

PWM1 = 192

C0h

Set LED0 to LED3 on

00h

Set LED4 and LED5 to PWM0, and LED6 or LED7 to PWM1

FAh

Set LED8 to LED11 off

55h

Set LED12 to LED15 off

55h

STOP

P

Blink period

1

PSC0

1

+

44

-----------------------

==

256

PWM0

–

256

--------------------------------

0.5

=

Blink period

0.25

PSC1

1

+

44

-----------------------

==

256

PWM1

–

256

--------------------------------

0.25

=