Well Tony


        I didn't understand one thing, do you want it to count 0,1,...,10,0,1 or
up and down 0,1,...,9,10,9,8,...1,0,1,2,... and so on. Or do you nedd both.

        If you want to count up continues ...9,10,0,1,.. you just have to detect
10 and them (using AND gates again) direct 1 clock pulse to the MR pin
instead of the clock up.
        The switching of the clock bettwen clock up and MR can be obtained just
combining logic gates, you dont even need a F/F. But if you want it to be
synchronus (less sensitive to noise and to propagation delays) you can set
up a F/F with the J/K inputs activated by the detection logic and clocked
in the oposite fase of the counter clock.

        In the other option, you have to do is to detect when it as reached 10.
In
that situation you switch the clock pulse to de oposite direction (the chip
as separate up and down clocks), them when it reaches 0 you switch again.
        The switching is obtained using two AND gates to control the clock and o
ne
F/F to select the state UP or DOWN. You conect the J to 0 detection circuit
and the K to 10 detection circuit and clock in opposite fase to the counter.

        The clocking of the F/Fs in oposite fase is to make sure that they switc
h
state in bettwen counting clocks. As the counter clock are positive logic
(rising edge) you make sure the F/Fs have negative logic clocks or else
feed them with an inverted clock.


        Hope theis helps.

        Best of luck

        Jorge F

PS: I'm not in favour of doing someone elses school works, because that
someone else becomes the looser of the tale. But I don't mind giving some
directions and warning for possible pitfals.


At 08:47 98.03.19 +0100, you wrote:
>At 18:57 1998-03-18 EST, you wrote:
>>Hi..
>>
>>*I have a non PIC related question. *
>>
>>For class project.. I had to build a simple modified binary up/down counter
>>from a 74193 IC that counts from 0 to 10 and repeats. (Yea I know it sounds
>>simple huh? Well I'm new to digital) Now being so fascinated by how that
>>works.. and for extra credit, I have to come up with with a way to make the
>>counter count from 0 to 10, then from 10 back to 0 and keep cycling and I
>have
>>only the following to use:
>>
>>74193 binary counter
>>and/or/nand/nor gates
>>j-k flip flops
>>
>>If someone could kindly steer me in the right direction, I'd really
>appreciate
>>it.
>>
>>
>>- tony
>
>Use a PIC and write "74193" on top of it!    ;)
>
>Wel:, dont cheat, work on further with open mind.
>
>/Morgan
>/  Morgan Olsson, MORGANS REGLERTEKNIK, SE-277 35 KIVIK, Sweden \
>\  mrt@iname.com, ph: +46 (0)414 70741; fax +46 (0)414 70331    /
>
===============================================================
cumprimentos / best regards
      Jorge Ferreira          mailto://jorgegf@mail.telepac.pt
------ Make sure brain is in gear before engaging mouth -------
===============================================================