Interfacing 555 and AT89C2051

[sunil21]

I am planning to make a 5 channel chaser circuit. Presently I have a circuit with 555 and 4017 counter, but i think about making one
with AT89C2051 , so that i can do many patterns for the chaser like reverse, forward, 10101,11111,00000 etc...
I can do this with MC but to control and alter the speed i am thinking about feeding the output pulse of 555(speed is controlled by a 100k variable) to input port of MC, is it okay to feed it directly to port (will it damage the port) ,, and also the code??
Presently i have the connection on my bread board the output from pin 3 going to an LED thru a 1k resistor.
Do i need to use an optoisolator?

(I searched thru this forum and i found few questions and one with solution and link to a project of almost the same nature, but the link no longer exists)

 

[klystron]

You can do everything with the MC, you do not need the 555 and 4017. Everything in SW code

 

[sunil21]

ignore 4017 ok..
As u said i will do it with 89C2051 but how to control the speed , It shouldnt be constant must vary....

 

[klystron]

Control the speed with Up and Down buttons

 

[sunil21]

each time when it is turned on?????

 

[klystron]

Give me more detail on your requirements / specifications. You can have a start frequency of 100 Hz and then adjust it up or down with the buttons

 

[sunil21]

Lets not waste much time on this.. Let me get it straight...
My requirement is, i am creating a pulse with 555 timer and giving it to AT89C2051 input port. 5 other ports will be outputs(LEDS).
Based on the 555 pulse the port LED should light accordingly.
Question is how to given the 555 output to MC input.. and process..

 

[klystron]

You can read a RC time constant on an input pin. By varying the R value you can change the frequency. You do not need the 555. See http://www.atmel.com/Images/doc0524.pdf