up/down counter using half adder ?

[truebs]

half adder counter

Hello friends..
can you tell me something about designing a up down counter using only half adders (and flip flops) say for 4 bit ?

VHDL code would also do ...or a logic diagram or a link....?

thanks....

 

[tarkyss]

counter with half adders

how many half adders?
two half adders are equal with a full adders,
only one half adders?

 

[truebs]

couter using half adder

any number would do....the aim is to create a 4 bit up/down counter using half adders...(it would need 4 as far as i know)

 

[tarkyss]

counter half adder

you can use two half adders to consist of a full adder
then use full adder to build your counter

 

[anjali]

implementing counter using adder

full adder = half adder + half adder

to implement up counter, pass present count + 1
& we have to store the present count ie register the present count, which is initially 0.

in this way, we can implement up counter.

to implement down counter, present - 1

we can implement subtractor with an adder, with inputs, operand1 & !(operand2)

implementation of up/down counter:
let control signal = 0 for addition,
= 1 for subtraction.

then inputs for the counter are, operand1 & XOR(operand2 , control signal).