help on a project!

[ah_Hui]

Hi guys, I'm a beginner to electronic stuffs. I need some advice for my project.
i intend to build a atmel 89c51 based countdown timer. the countdown timer consists of 4 common anode 7segment displays(2 for hours and 2 for minutes) and all 4 7segment display are connected to 89c51.
here's my application, once the countdown timer reaches zero, it will trigger a stepper motor or a normal dc motor(also connected to 89c51).
in addition, there're 2 button to increase the timer(1 button to increase hour and another 1 to increase minutes) digits as well and also a start button to starts the timer.
can some 1 gimme an idea?

here's my question.
what decoder exactly to use for the 4 7segement display?..can i use 74ls47 to do it? to simplify my programming...etc..
the mose difficult part i think is the programming on the 89c51.i hope some one here can provide me a good site with assembly language tutorial as well...

thx guys...

 

[ljcox]

Why use a microprocessor.

For such a simple application, all you need are decade counters.

See the post by johnsoax dated March 6, 2004 and my responses.

I did not post the final circuit as I corresponded directly with him via email. So, if you wish, I'll post the final one for you.

Len

 

[ah_Hui]

another thing is..
i wanna add a button to my circuit so that everytime the button is pressed...it will alternate 3 different levels ...i.e high, medium and low
these levels actually decides how long the motor rotate before it goes off..
for example...for low..the motor will rotate a very short period...and so on...
in the beginning i thought microprocessor can solve my problem...since i'm a newbie to electronic stuffs...