Len,
Thanks for the response, I am glad you are still here after all this time.

Having 999 from the counters to the Tx would be fine but I only have eight positions on the Rx and have purchased the 8 position DIP switches. If I use the 8 positions as two sets of four and then match what I get from BCD, I will only end up with 99 instead of 256.

To top all that off, I found a kit that has a 4 digit up-down counter. So, I will use this to replace what I have done so far. This kit has everything except the buttons. With this and a binary counter circuit using your debounce circuit, I will end up with everything that I wanted. I will have the 4 digit to display the decimal value of the coding and have the binary counter to set the coding. I will integrate the interface circuit into this new binary counter, only 8 bit for now, to connect the counter to the transmitter encoder chip. This way, the Tx and Rx will match. Then, down the road, I can add one more switch to the Tx and Rx to select the H/L option, since these lines are all connected I will just need a DPST switch, and have two sets of 256. I think 500 combinations will last me for some time.

Thanks again
Sean

EDIT: Just doing a little tinkering with the 8 bit counter that I originaly purchased. I ahve been reading the datasheet and it is a little more complicated to hook up. There are a few pins that I have to hold low for them to be active, like the output enable. I know you said that I shouldn't use this IC, I am just tinkering untill I can find something else to use.

 

I had a small epiphany last night while I was trying to sleep. The 8 bit counter that I bought is what they call tri-state. The encoder chip is also tri-state. Based on this, can I hook the counter to the encoder in a way that will net me all 6561 combinations?Does the tri-state on the counter mean that it has floating, Low and High as output states like the encoder has for the inputs?

The encoder that we have been working with has the 12 pins that we were originally trying to connect to the 12 outputs from three BCD counters. These 12 pins are normally used as 8 pins for encoding and 4 pins for data. All twelve pins are tri-state. That gives me the 6561 combinations from the encoding and 81 more from the data pins. That gives me 531441 total combinations.

Since I want my finished system to be expandable, I would like to use a tri-state counter to give me all the possible combinations. So, If the tri-state works as I have describes above, does anyone know a part number for an 12 bit up/down counter with tri-state outputs? Something similar to the 74F579 that I have but not as fast.

 

Sean,
You're misunderstanding the Tri State.

You're assuming that any output can be L, H or TS. Not true. When the outputs are set in TS, all outputs are in TS.

TS is used for "bus" connections. For example, several RAM memory chips could be connected to the same data bus. All are normally in TS, but when the CPU wants to address a particular chip, it disables the TS of that chip only so its outputs are connected to the bus so that data can be transferred to the CPU from that chip. I suggest you do an internet search for TS.

__________________
Len

 

Sean,
You could have 2 counters (ie. one BCD and the other binary) counting in unison, but there is a possibility that they may loose sync (due to a noise pulse or some other reason).

Given that you're setting off fireworks, it seems to me that this could be a safety issue, ie. you would fire the wrong one if the counters loose sync.

It would be better if you had a BCD counter with a BCD to binary converter.

Let me know if you want to persue this option and I'll post a suggestion.

__________________
Len

 

Len,
is there something like a display driver that can take the binary out and run a 7-segment? I have three BCD to 7-seg now, is there a binary to 7-seg?

This would allow me to run only one counter and still have the decimal display to know what channel I am on.

If this is not an option, could you explain the BCD to binary conversion? Will it work the same as what I mentioned above except it would be a BCD counter and have the output going to the driver and the converter?

Thanks
Sean

 

I found this site,
http://www.asic-world.com/digital/gates5.html
At teh bottom of the page, he explains TS. Is this correct? Right now I don't understand most of it. All I see is H, L and floating. Just like we have on my encoder chip.

Are you saying that TS outputs and TS inputs are not the same?

Thanks

 

Yes, this would be the best option.

The display would be in hexadecimal rather than decimal, ie. 0 ~ F not 0 ~ 9.

I believe some display drivers provide hex.

I'll have a look at the data sheets that I have on hand and let you know.

__________________
Len

 

This is a good site for general info.

TS inputs and outputs would be compatible if the outputs could be controlled individually as in the TS NAND gate shown in the site.

But I have never seen a TS NAND gate.

The only TS I have seen are in ICs such as memories, buffers, etc.

In these cases, all of the outputs are set into TS when the appropriate signal (ie. H or L) is applied to the control line; in other words, there is only one TS control line rather than a control line for each output.

__________________
Len

 

OK,
I have gone over some things and I have a question. On a normal counter like the ones I am using, The active output state is high correct? What is the state of the outputs when they are not active? I thought I read in here that they are floating. If both of these assumptions are true the would not the same be true for a counter that has active outputs low? If all of these assumptions are true then would a counter chip with the capability of high or low outputs have three possible states, High, Low and Floating? Am I totally wrong on this or what? I think I may have confused the issue when I mentioned tri-state. As I see it, a tri-state has a different three states, High, Low and high impedance with the high impedance being applied to all output pins when it is active.

Are these definitions correct? -
Floating - having neither a high or low state but a voltage that falls below the high threshold and above the low threshold.
High impedance - not connected, the same as physically disconnecting.

Sean

 

Sean,
I thought about your project while we were away (not much else to do at mother-in-law's).

After considering various options, I concluded that the configuration I suggested previously is the best, ie. 3 decade counters and decimal displays.

The advantages of this are:-
1. hexadecimal displays are not required.
2. you can have up to 1000 Rx (or 999 if you choose to exclude zero)
3. The Tx circuitry is simple - no BCD/Binary code conversion, etc.
4. It is easier to set the BCD codes (rather than binary codes) in the Rx.

Now I know your objection to this is that you want to use 8 bit switches in the Rx since you want to use all 256 combinations.

I accepted this point originally, but now I'm not so sure.

I assume that the Rx have 12 code setting inputs the same as the Tx. Is this correct?

If so, then to go beyond 256 combinations, you will have to add extra switches. So why not add them at the outset?

Thus the first 4 switches would set the Hundreds digit (in BCD), the next 4 the Tens digit and the last 4 the Units digit.

It is very easy to remember the BCD codes, but not as easy to remember the hex codes.

The DIL switches come in various sizes - 2 way, 4 way, & 8 way, so you could install either an 8 way and a 4 way, or three 4 ways. See http://www.altronics.com.au/index.as...=item&id=S3050 {This is an Australian supplier, but you should be able to buy then in the US also}

You can also buy DIL switches that mount vertically and they have 1/10 th inch spacing between pins. See http://www.altronics.com.au/index.as...=item&id=S3094

Let me know what you think and - assuming I have not missed something - I'll draw a circuit and post it.

Attached Images

Gating.gif (7.8 KB, 5 views)

__________________
Len

 

OK, The receiver has the same data and encoding options as the transmitter. So, This makes things a little simpler. Here is a link to the receiver IC datasheet.

I will take a look at the attachment above and reply on it later.

Here are a couple pics of the receiver board.



Sean

 

Due to some enlightening PM from Len, I am back to where we started.

The plan now is to get the counter put back together on the proto board, I took it apart when I thought I could use the counter kit I found at Circuithut.com

When I get the counter put back together I will be trying to integrate it with the Tx. Len, One of your PMs said I would have to unsolder some stuff on the Tx board. Does this still apply?

Sean

 

Sean,
Do you have a circuit of the counter kit?

It may be possible to convert it to count in BCD. What counter ICs are on it?

__________________
Len

 

Len, you made the comment in the first "another suggestion" PM that you sent me. Here is a copy of the line that I am talking about.

My Tx actually has a variation on this diagram. It has jumper pins instead of switches shown and there is only one resistor in that section.

Sean

 

I am putting this in a separate post because the last one was getting big.

So, I do not think we can use the CircuitHut.com counter kit because it only has one IC on it. It is probably doing some kind of MUX. Besides, I only need the three digits that we already have.

I have my counter circuit put back together and it is working again.

I have noticed something lately, both before I took the counter apart and now that I have put it back together. When I first turn the circuit on, the up and down buttons will act funny. If I hit the up button it will either jump to 2 from zero or it will show 1 and then go back to 0 when I let go of the button. the weird part is that if I leave it alone for about a minute then the counter works properly with no errors. Any Ideas what could be causing this? I may have found something on this. At the same time the problems started, I put the receiver on the board so that I could borrow the power supply. I have only tried this once but when I took the receiver off of the board before putting turning the counter on, I did not have the problems I mentioned. However, when I put the Rx back on the board, it did not cause the problems.

I am now back to waiting for the funds to put in another order to the parts store. I still need to get the three buffers. I am going to get everything else I need at the same time to save on shipping . So, It will be a couple weeks before I can place the order. Even 0.83 cent items get expensive when you have to get 100 of them.


Sean