binary to BCD

[teragiga]

Hi
I'd like to drive a double display 7segments from an analogic input.
Therefore I m building a system based on A/D converter, binary to BCD, BCD driver for 7sements.
Unfortunately I managed to build everything execept the binary to BCD part.
It seems there are some IC (74185AN ) but they are discounted
Any suggestions ?
The task is so easy I don't want to use a PIC and the other solutions I found in this forum are too crazy for me... there must be an easy way.
Cheers

 

[MikeMl]

Sure, just buy a $10 digital panel meter.

 

[teragiga]

That is just a ICL7107 + 3½digit + resistors and caps. If you buy this stuff in stock they could be even 3$ (7 $ for the engineering part :).

What I am talking here is exactly how to reproduce with discreet component something like the ICL7107, and it seems the critical point is the binary to bcd,
I am afraid there is no other possibility than reproduce it with counter and register.

 

[teragiga]

You know?, you are probably right... it is not worth turning crazy for this... I ll try on of this ICL7106 or similar.

 

[crutschow]

Binary to BCD conversion is not as simple as it might appear. See this for a discussion.

 

[teragiga]

I have already read this message... I was just hoping that that since 2009 there were some evolution.
I think the main point is that this kind of works are performed since many years by PIC, therefore the company are not interested anymore in producing specialized chip and the technology simply get obsolete. This means that a normal person probably implements this business using a PIC. I am thinking as an outsider... not necessarily I am right.

 

[Gary B]

The simple way is to load the BCD into the lower 4 bit positions and 0x3 into the upper 3 positions. The net result is:
0 BCD= 30ASKII
1 BCD= 31 ASKII
2 BCD= 32 ASKII
3 BCD= 33 ASKII
4 BCD= 34 ASKII
5 BCD= 35 ASKII
6 BCD= 36 ASKII
7 BCD= 37 ASKII
8 BCD= 38 ASKII
9 BCD= 39 ASKII

 

[crutschow]

The simple way is to load the BCD into the lower 4 bit positions and 0x3 into the upper 3 positions. The net result is:
0 BCD= 30ASKII
1 BCD= 31 ASKII
2 BCD= 32 ASKII
3 BCD= 33 ASKII
4 BCD= 34 ASKII
5 BCD= 35 ASKII
6 BCD= 36 ASKII
7 BCD= 37 ASKII
8 BCD= 38 ASKII
9 BCD= 39 ASKII

There is no BCD to load. He needs binary to BCD conversion.

 

[B F Clanton]

I am going to jump in here because I need the same thing. What I really need is to add 2 4-decmal BCD bits together. If the sun is greater than 9 then for each digit them I'm stuck. So I thought I would add it in the binary state then convert it to BCD. Maybe one of use can figure something out.

 

[B F Clanton]

If you have not found the answer yet I have. I am going to buy a bunch of these chips before they become obsolete, like the 74185. Which I did fine one in my old stock but I need 2

https://tams-www.informatik.uni-ham...bdemos/20-arithmetic/10-adders/bcd-adder.html

This is a tremendous resource.

 

[ljcox]

The other Full Adders that are still available are:-

4008 & 74LS283

 

[ljcox]

Another way to do it (ie. convert 8 bit binary to BCD) would be to use 2 counters.

One an 8 bit (or 2 x 4 bit) presettable counter that can count down.

The other, a dual BCD counter that counts up.

Load the binary number into the binary counter & reset the BCD counter.

Apply the same clock pulses to both counters until the binary counter reaches 0.

Then the BCD counter should be at the BCD equivalent.

The 4029 counter is presettable, can count up or down & can be configured for BCD or binary.

So 4 of these ICs plus some control logic would do what you want,

PS a PIC would be much easier.

 

[B F Clanton]

Actually the 74ls83 is no longer available and was replaced with the 74HC283. The only difference is the pin-out. What I am doing is taking data from 2 4-digit BCD outputs then adding or subtracting them then outputting them to a 4-digit 7-seg display. A PIC would be easier and will be used on the next project. At the moment I know a lot more about logic than I do PICs. I don't have time for a learning curve at the moment, will need to work that in later.

 

[ljcox]

Yes, I was in the same situation a few years ago.

But I eventually took the time to learn how to programme PICs & have used them since.

 

[atferrari]

ASKII, a variety of ASCII?

No visual memory?