I'm currently in the beginning stage of doing a project that requires me to build a 7 segment LED to display a countdown timer. I've been looking for some information regarding 7 segment display driver on the internet. But just couldn't find any that's related to my small project.
Can I use a 555 timer to do this project? Or should I use a microcontroller?
Are there anything else that I need to look for?
Any website for my reference?

Thank you guys..

 

You can do it all with logic ic's like the 40-series or 74-series. But it will become a pretty complex design. Using a microcontroller would enable you to get (almost) everything into a single chip.

But you get the overhead of learning to program them.

 

How many digits? Like ah_hui said, you can get as crazy as you want with 74xx logic (I recently built a color LCD controller using all 74xx logic). Using a microcontroller won't cost much more... the programming software is free and you can build a programming interface for a couple of bucks, but you'll have to learn C or Assembly and the microcontroller's architecture.

Post more details of your design and you may get more advice.

hth,
j.

 

You may want to check out the 4 digit up down counter kit by Carls Electronics: http://www.electronickits.com/kit/co...lec/ck1612.htm

The kit is less than $20.00 and works very well. I built a number of them
for a client. They are 7 segment LED displays.

__________________
The great thing about electronics is unlimited ways to do the job. The only limit is one\'s imagination. I generally think my way is best.
Show me a different way. I have an open mind.

 

i have build a countdown timer(from 19 to 0 only) for a rocket launching device. the counter stops at 0 and triggers a relay.
if you are interested i can post the schematic. the circuit uses 4000 series IC's.
i can modifiy it to count from 99 to 0. also, do you need it to stop when it reaches 0???

 

first of all...thanks you guys..
hmm..
actually i want my timer to display in time instead of just numeric numbers..
basically i need 4 digits, 2 display hours and another 2 display minutes. So, when the counter reach zero, it will trigger a stepper motor to move a step, after that the timer will go back to the initial stage and countdown again.
I intend to use a micro controller to do this task. Atmel 8051, i know this thing is old..but i think it's the cheapest around..

 

here are my project link
http://fet-training.mmu.edu.my/FYP/s...rojects_id=446

here i include a brief description of what i'm going to do
4 7segment display as timers
2 digit to display hours, another 2 display minutes
once finish counting, trigger a stepper motor to open up a hole at the bottom of the funnel. fish foods contains inside the funnel...
then the timer go back to initial stage and countdown again.

there are total of 5 buttons.
1. Start the timer
2. Reset the timer
3. Set the hour timer (increment 1 everytime i press)
4. Set the minutes timer (same as above)
5. to adjust how many step does the motor move. I use tis button to alternate 3 different level. 3 additional LEDs to indicate these levels. Hi,medium,low.
(for example, if i set to Hi mode, the Hi-LED light up. then the stepper motor move 3 steps to open up a big hole at the bottom of the funnel so that large amount of food can be dropped. If i set to low mode, motor move 1 step to open a small hole at the bottom of the funnel, same goes to medium mode.)

my question is...can i use atmel 8051 to do this...with assembly programming..

thanks...

 

Any micro-controller would be more than enough, it's not a very demanding task - as for assembler, you can write anything in assembler, it's the nearest thing to what the processor actually runs. All high level compilers do is generate the assembler for you, which usually creates longer, slower, code (even if only slightly) - but for your application that wouldn't be a problem anyway.