Designing a Kitchen Timer using IC's and logic gates .

Thread Starter

rellik650

Joined Mar 29, 2016
6
Hello , I want to create a Kitchen Timer that has 3 input buttons : 'Start/Stop' , 'Set Minutes' , 'Set Seconds' .1)When you set minutes and seconds and press Start/Stop , the timer starts counting down until reach 00:00 on a BCD 7-segment Decoder ,activating an alarm(or just an simple led) .2)If the output is 00:00 and you press Start/Stop button it count up to 99:59 and then 00:00(and it stops).
Do I need 2 sets(1 set = 4 counters , 2 for minutes , 2 for seconds) of counters to produce the both cases?How to design propely?
 

Alec_t

Joined Sep 17, 2013
10,739
Cheaper to buy one than build one.
Are you building this to gain experience, or simply because you need a timer?
 

tracecom

Joined Apr 16, 2010
3,944
Here is a video that describes a countdown timer similar to what you are wanting. The project was designed by another member here and built by me; it does a little more than what you want, but not much. As you can see, the project is a bit complicated, but it may help you understand why some of the responses recommend buying rather than building.

 

Thread Starter

rellik650

Joined Mar 29, 2016
6
I know that the idea of buying is better than building . I want to implement it to a FPGA so I need a basic scheme to see the internal process .
 

AnalogKid

Joined Aug 1, 2013
8,259
In the FPGA library there should be a presettable decimal up/down counter with both carry and borrow signals, similar to a 74LS168. One set of four of these form the counting core of the circuit. Then add steering logic around them to handle the operational conditions.

ak
 

ian field

Joined Oct 27, 2012
6,539
Most of them are done via specialty asic or mcu.
Kitchen timers have always been a popular page filler in various electronics hobby magazines.

There are probably PIC or AVR based variants in more recent issues.

Probably a few projects floating about the web too.
 
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