PCA9551 Philips Semiconductors, PCA9551 Datasheet - Page 11

• Manufacturer Part Number: PCA9551
• Description: 8-bit I2C LED driver with programmable blink rates
• Manufacturer: Philips Semiconductors

Philips Semiconductors
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.
Table 1.
2004 Oct 01
Start
PCA9551 address with A0–A2 = LOW
PSC0 subaddress + auto-increment
Set prescaler PSC0 to achieve a period of 1 second:
Set PWM0 duty cycle to 50%:
Set prescaler PCS1 to achieve a period of 0.25
seconds:
Set PWM1 output duty cycle to 25%:
Set LED0 to LED3 on
Set LED4 and 5 to PWM0, and LED6 or 7 to PWM1
Stop
8-bit I
256 – PWM1
256 – PWM0
Blink period
Blink period
256
256
2
PWM1 = 192
C LED driver with programmable blink rates
PWM0 = 128
PSC0 = 37
PSC1 = 9
0.25
0.5
1
0.25
PSC0
38
PSC1
1
38
1
I
S
C0h
11h
25h
80h
09h
C0h
00h
FAh
P
2
C-bus
11
PCA9551
Product data sheet