Philips Semiconductors
4-bit I2C LED dimmer
Programming example
The following example will show how to set LED0 and LED1 off. It
will set LED2 to blink at 1 Hz, 50 % duty cycle. LED3 will be set to
be dimmed at 25 % of their maximum brightness
(duty cycle = 25 %). PCA9533/01 is used in this example.
Table 1.
Start
PCA9533 address
PSC0 subaddress + auto-increment
Set prescaler PSC0 to achieve a period of 1 second:
Blink
period
+
1
+
PSC0 )
152
1
PSC0 = 151
Set PWM0 duty cycle to 50 %:
PWM0
256
+
0.5
PWM0 = 128
Set prescaler PWM1 to dim at maximum frequency
Blink period + maximum
PSC1 = 0
Set PWM1 output duty cycle to 25 %:
PWM1
256
+
0.25
PWM1 = 64
Set LED0 on, LED1 off, LED2 set to blink at PSC0,
PWM0, LED3 set to blink at PCS1, PWM1
Stop
I2C-bus
S
C4h
11h
97h
80h
00h
40h
E1h
P
Product data sheet
PCA9533
2004 Oct 01
10