A/D Parallel output to 7 Segment

[Overclocked]

I will be using an ADC0801 A/D converter for a small project, the output is Parallel (Db0 to Db7). Is this the same as BCD? What I plan to do is to interface it to a BCD to 7 segment IC, but will it work?

I figured it would since BCD, and parallel output are the same, they are of course binary.

 

[ClydeCrashKop]

Binary Coded Decimal is from 0 to 9. 8 bit binary is 0 to 255. It will work all right until you get over 9, then you will get fictitious numbers.

 

[oldtimer]

You need to reset it after 1001 with a gate .

 

[Papabravo]

BCD and binary are most assuredly not the same. Unless the A/D converter has BCD outputs your proposed design is doomed.

 

[ThermalRunaway]

You could always make a BCD Encoder for the output of the ADC. As a side-issue, bear in mind that the ADC0801 is designed mainly for use with a microprocessor. That doesn't mean you can't use it as a standalone device - you can and it'll work fine, but you'll want to look up the timing diagrams on the datasheet because you've got to connect it up in a certain way to get it to work on it's own. I managed to figure it out when I used one as a standalone so if you get any problems I'll have a quick look at the datasheet for you - I'm sure I can figure it out again!

Brian

 

[ThermalRunaway]

Hang on, something's telling me it was an ADC0804 that I once used not an ADC0801. So I might be wrong about the whole micro interface thing.

Brian

 

[Overclocked]

You could always make a BCD Encoder for the output of the ADC. As a side-issue, bear in mind that the ADC0801 is designed mainly for use with a microprocessor. That doesn't mean you can't use it as a standalone device - you can and it'll work fine, but you'll want to look up the timing diagrams on the datasheet because you've got to connect it up in a certain way to get it to work on it's own. I managed to figure it out when I used one as a standalone so if you get any problems I'll have a quick look at the datasheet for you - I'm sure I can figure it out again!

Brian

Luckly for me, I found a chip to do all that work . Can convert BCD to Binary and Binary to BCD. (DM74184/DM74185A BCD-to-Binary and Binary-to-BCD Converters) The only problem is Ive only found one place that still has them, mouser,newark, nor allied (or digikey) has them in stock.

Intrestingly, Ive found A/D that have BCD outputs or have 7segment display outputs integrated in the chip. I might go for those, if I can find one thats easy to use.

What Im trying to do is convert a voltage from a sensor to be read on a display (in my case-LM35, the data sheet shows how to do it, which is why I was going to use that chip)

 

[ClydeCrashKop]

Sorry guys. I screwed up exponentially!

 

[ThermalRunaway]

As it happens, when I used the ADC0804 I was using it to convert the output of an LM35 as well!!!

Brian

 

[Overclocked]

Ivefound a chip that will practically do it all! Its outputs are BCD and needs no control lines or clock ! All the chip needs is a couple caps and some resistors, along with the decoder chip for the 7segment.

I have another question, reguarding the LM35. I am trying to figure out what the voltage will be at a certain temperature. The data sheet says 10mV/C. Is this 10mV Per C or is it 10mV Divided by C to get V out? The A/D has a 200mV and 20V Capablity.

The A/D Converter is CA3162.

 

[FRIED]

Degrees K, °K
(DM74184/DM74185A BCD-to-Binary and Binary-to-BCD Converters
Not made any more

 

[ThermalRunaway]

It means that the voltage output from the LM35 will increase by 10mV for every one degree rise in temperature.

Brian

 

[Overclocked]

It means that the voltage output from the LM35 will increase by 10mV for every one degree rise in temperature.

Brian

So then 200mV Scale wont be enough, since at room Temp (25C) I will be getting 0.25V. So then will a 2V Scale be enough?

 

[ThermalRunaway]

Well it depends on your application. A 2V scale would give you enough room to measure up to 200 degrees C, although I think that far exceeds the capability of the LM35. If I remember from when I used it, it tops out at 50 Degrees C?

Brian

 

[Overclocked]

Well it depends on your application. A 2V scale would give you enough room to measure up to 200 degrees C, although I think that far exceeds the capability of the LM35. If I remember from when I used it, it tops out at 50 Degrees C?

Brian

150C. Full range is from -55 to 150C.

Ive figured out how to calibrate it already, since it wll be reading in C, all I have to do is get a certain voltage (say .5V for 50C) and adjust the display so it will display 50. Of course I might leave the decimal out, but I'll leave the negative sign in.

 

[Overclocked]

Should I use the regular circuit or the circuit for temperature sensing? The circuit for temp sensing uses a transistor. It looks like the temp sensing circuit also gives me control over Zero adjust, the other pot is for scale (instead of just 2V, or 200mV It can be changed)

 

[ThermalRunaway]

Oh right, I was certain that it topped out at something like 50 degrees C, and I didn't think it was capable of going very far negative. Mind you, there was a military version of the LM35...

Brian