analog to digital converter

[victorcarlos]

hello, is there a way to put 3 digits in a adc0804? the output is in bcd , i used bcd to 7 segment converters , but i dont know how to put a third digit to make the circuit measure up to 255 (8 bits).

 

[Brevor]

The ADC0804 outputs data in binary not BCD. You need to convert the output to BCD to get 3 digits (256 values) The best way to do this is with a microcontroller. You could even eliminate the BCD to 7 segment decoders and do it all inside the microcontroller.

 

[Nigel Goodwin]

And eliminate the ADC0804 and use one inside a micro-controller - your project then becomes a single chip and a little software.

 

[on1aag]

Binary to BCD conversion.

Hi victorcarlos,

If you must, if you really insist, there's a way to do it.

https://www.alldatasheet.com/view.jsp?Searchword=74184

See figure 5 at page 7.

Don't tell any one you've heard it from me.

on1aag.

 

[Roff]

Hi victorcarlos,

If you must, if you really insist, there's a way to do it.

https://www.alldatasheet.com/view.jsp?Searchword=74184

See figure 5 at page 7.

Don't tell any one you've heard it from me.

on1aag.

Actually, it's figure 6.

 

[victorcarlos]

this is a school project, i have to use the adc0804 . the outputs of this chips are (example) 00000000=0 ,01010101=85 ,11111111=255 , is not this type of output bcd? i can use a 7447 directly and it works fine , but i can only make up to 2 digits i dont know how to make a third digit to make the adc measure up to 255. Im not allowed to use microcontrollers in the class cause is "the basics of logic" and microcontrollers are part of the "advanced class".

 

[j.p.bill]

I guess you were asleep when the instructor talked about binary numbers. BCD is binary coded decimal. Try latching your 8 binary digits in a register and using the value to count up a chain of BCD counters. that will convert from binary to BCD for you. Those outputs can drive the 7447 (where does all this old TTL come from?) to make the numbers.

 

[victorcarlos]

thanks for the info , thats what i needed to know. lol maybe not asleep but absent 1 or 2 days

 

[Leftyretro]

thanks for the info , thats what i needed to know. lol maybe not asleep but absent 1 or 2 days

That's OK, I've met plenty of software programmers that couldn't keep their bins, bcd, hex, ASCII straight either

Reminds me of a troubleshoot effort over 20 years ago trying to convince a programmer that sending the letter O was not the same thing as the digit zero!, and the problem was not in the modem or phone line....

Lefty