9551 Ver la hoja de datos (PDF) - Philips Electronics
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9551 Datasheet PDF : 21 Pages
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Philips Semiconductors
8-bit I2C LED driver with programmable blink rates
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.
Start
PCA9551 address with A0–A2 = LOW
PSC0 subaddress + auto-increment
Set prescaler PSC0 to achieve a period of 1 second:
Blink
period
+
1
+
PSC0 )
38
1
PSC0 = 37
Set PWM0 duty cycle to 50%:
256
– PWM0
256
+
0.5
PWM0 = 128
Set prescaler PCS1 to achieve a period of 0.25
seconds:
Blink
period
+
0.25
+
PSC1 )
38
1
PSC1 = 9
Set PWM1 output duty cycle to 25%:
256
– PWM1
256
+ 0.25
PWM1 = 192
Set LED0 to LED3 on
Set LED4 and 5 to PWM0, and LED6 or 7 to PWM1
Stop
I2C-bus
S
C0h
11h
25h
80h
09h
C0h
00h
FAh
P
Product data sheet
PCA9551
2004 Oct 01
11
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