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xnihilo
- 28th May 2008, 15:00
hi,

i'd like to switch between 10 outputs using a 4017 decade counter.
let's say i'm using 10 leds which anode is linked to one of the 10 outputs.
i have to connect vdd an vss, obviously, then the clock pin to a pin of my pic, the clock enable to another pic pin and the carryout to the clock pin of another 4017 if desired, right?

If i understood well the datasheet, by default, output 0 will be on. to switch to next outout i have to input a positive voltage to clock pin AND bring clock enable pin low, is this right?
even if i put a positive voltage on clock pin, it wont switch to next output, right?
Last thing, the switch to next output happens only on the rising edge of the clock pin, right?

mister_e
- 28th May 2008, 15:09
Maybe not 0 as default, but for sure 0 after a reset. Look at the Functional Truth Table (page 2 of the following PDF).
http://www.onsemi.com/pub_link/Collateral/MC14017B-D.PDF

Clock Enable can be connected to Vss all the time, so the output will shift at each clock rising edge.

What i would do is to connect Reset and Clock on the PIC, and Clock enable to Vss.

Check PDF page 3, Output Drive current... not a good idea to use this chip as is to drive LEDs... maybe you have high efficiency ones? Spec might be different from brand to brand though... worth a look.