Need help designing circuit

A truth table would really help: both for visualizing the problem AND for validating the requirements (i.e. so we are clear on our understanding of your description of the problem).

Hi

As collin says you would have to use a micro No choice in that at all

The truth table you have is also incorrect

Assuming this is going into a vehicle you would have ignition sence that would be (power on / off = two states one pin )

This wakes up the cpu from a sleep function (on interrupt wake up cpu )

D is simply an internal register that counts and performs a maths mod count function to see if odd or even


Push button attached to a counter The counter records number of times button pressed hence your counter You can use another register. bit to record if button has been pressed giving you true or false

You then need another pin this reflects output state This drives your output high or low that can be set for active high or Active low depends if you want dual configuration

So now you truth table is some what different

[code]
A = switch
B = supply state on or off
C = boolean true of false indicating switch press
D = output

[/code]

Now what you need to do is go back and re do your truth table

Having only two built is not an issue I can do that for you , plus supply you with a blown chips plus pcb , plus schematic

No problem at all Quite easy for me to do about one days work in total start to finish

However you will need to contact me privately

There are my details contact me to arrange if you are interested

Have a nice day

eliteelectronics2010(_at_)hotmail.com

How about a PICAXE: http://www.picaxe.com/
Or Arduino?
Those are pretty cheap ways to achieve a uController solution.

But, a uController is not always the best solution. But, having said that, I have to admit that I don't have time, right now, to analyze such a complex system.

Try looking into "Karnaugh mapping" to reduce this to a manageable logic array. You might find you are able to solve this with a simple set of basic, discrete logic elements.

OK, so this morning I _did_ take some time to look at your truth table, and I can't make heads or tails out of it ;)

Your truth table has no discernible Output column(s) -- in other words there needs to be one column that shows the state of the "action" relative to the various inputs [and if there are interim outputs, then they need to be clearly bracketed]. As far as I can discern, the inputs are:

1. The momentary switch
2. "other source which can close that circuit as well"
3. The counter

In the current truth table, there is a column *C* that implies yet another input, but I suspect that this is really the inverse of column *B* and thus is redundant -- or _is_ there a third input (and if so, what is it)? Or is ~ *B* the same as *C*, in which case column *C* can be eliminated? But. once the Output column(s) is/are added, or are indicated (as in, tell me which column(s) is/are the output column(s)), then it will be clear if column *C* can be eliminated.

Also, in your truth table, I'm not sure what is going on in the columns beyond *A*, *B*, *C* & *D* -- I can't tell which binary columns correspond to which headings:

* Why is there a duplicate *A* column (after the *D* column)?
* After *A B C D*, there is *A*, then ( *C* & ~ *D* ), then ( *B* & *D* ) -- that suggests to me, only three more columns of 1's & 0's [i.e. binary columns], yet there are 10 more binary columns -- what's going on there?
* You indicate an apparent separation of "groups" in the header, using vertical bars ['|'], yet this is not reflected in the binary columns -- so, there is no way to know which binary columns you intended to be associated with which headings.

All I need to know is:

* What are the inputs (so one binary column for each input)
* What are the output(s) -- and go ahead and include the interim outputs [ such as *( C & ~ D )* ], but make it clear which binary column is associated with that interim output (i.e. by using vertical bars in both the header AND the in the binary table)
* What is the final output (i.e. the state of the "action" you're controlling with these inputs).

His logic table is incorrect anyway Steve for what he wants to do its that simple he doesn’t need to write a logic table for this application although his approach is in fact correct and they should be analyzing the logic and determining the output using predicate calculus which is what he is doing but What is more important is writing an algorithm and designing a schematic for this approach

First the Hardware then the software No pint I writing logic tables unless he has hardware design unless he going to put together a VLSI design then it make sense if designing a purpose built hardware

If he was designing an ALU or full adder circuit then his truth tables would be needed and he would have to do these

http://hyperphysics.phy-astr.gsu.edu/hbase/electronic/fulladd.html

I have a funny feeling that the pith taking is just about to come to halt here !! I wonder what makes me think this hmmm ?? Interesting question !!

I currently have a momentary switch that triggers the circuit to close and prompt the action to occur I would like to introduce another source which can close that circuit as well. The other source will trigger the action when its power is removed or added.

One caveat is that I need a counter so that if the momentary switch is pressed and then the power is removed from the other source, the action will not fire again. However, if the momentary switch is pressed an even number of times, the other source will fire the action as necessary.

Also, this circuit should only send a momentary signal, not constant.

I realize that I need a relay to monitor for the removal of power from the other source and a binary counter in order to keep track of how many times the momentary switch has been pressed.

This is going in a vehicle so the power requirements are low.

Any help with components and wiring that you all can provide would be much appreciated.

Truth Table as requested:


[code line="none"]

A B C D | A | ( C & ~ D ) | ( B & D )
-------------------------------------------------------

0 0 0 0 | 0 0 0 0 1 0 0 0 0 0
0 0 0 1 | 0 0 0 0 0 1 0 0 0 1
0 0 1 0 | 0 1 1 1 1 0 1 0 0 0
0 0 1 1 | 0 0 1 0 0 1 0 0 0 1
0 1 0 0 | 0 0 0 0 1 0 0 1 0 0
0 1 0 1 | 0 0 0 0 0 1 1 1 1 1
0 1 1 0 | 0 1 1 1 1 0 1 1 0 0
0 1 1 1 | 0 0 1 0 0 1 1 1 1 1
1 0 0 0 | 1 1 0 0 1 0 1 0 0 0
1 0 0 1 | 1 1 0 0 0 1 1 0 0 1
1 0 1 0 | 1 1 1 1 1 0 1 0 0 0
1 0 1 1 | 1 1 1 0 0 1 1 0 0 1
1 1 0 0 | 1 1 0 0 1 0 1 1 0 0
1 1 0 1 | 1 1 0 0 0 1 1 1 1 1
1 1 1 0 | 1 1 1 1 1 0 1 1 0 0
1 1 1 1 | 1 1 1 0 0 1 1 1 1 1


A: momentary button
B: power turned off from other source
C: power turned on from other source
D: binary counter in 0 state

[/code]


for some reason I can't reply to comments so I'll keep adding information in the main post.



I'm trying to avoid a microcontroller so that I don't have to purchase all of the required items to program it (IDE, compiler, programmer, board, etc).

I only plan on making one or two of these.



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I am unable to reply to comments as I get a error stating I'm unauthorized. I appreciate everyone's help.

Geoff, I am so sorry for the inconvenience. I have emailed you an inquiry into the particular error you are describing whilst attempting to reply to other user's comments.

I asked for a Truth Table because I wasn't sure I understood what he was asking for, and a truth table, done properly, lends clarity to the problem description.

But, there is another way: Use Cases.

So, Geoff, how about you tell us, in detail, what happens at each point in a session with the pushbuttons, the "other source", and the counter. Like this:

_To start with, other source is off, the action is ??? [and insert any other initial conditions]_
_Next I push the button and this happens...._
_Next I push the button again and this happens..._
_Next the source turns on and this happens..._

Continue with that narrative until you have covered all possible cases.