How to find digital input for given output value of a DAC ?

isurunix

Joined Feb 3, 2015
21
This is the Homework Help forum, not the Homework Done For You forum.

Please do NOT just do the poster's assignment for them -- in most cases it does them little good in terms of learning the material.
@WBahn Sorry for that. I just thought it will help him to get things straight. Won't happen again.
 

WBahn

Joined Mar 31, 2012
26,398
@Bertrus

Thanks for pointing it out. Can I post a link to a site containing relevant theories ?
Sorry for my mistake. I was browsing on the same question and most probably for the same home work. So I just hoped to make it easy for him to understand.
You intentions were laudable, but all you really do is make it easy for someone to claim credit for work they did not do while not understanding anything any better.

Live and learn.
 

WBahn

Joined Mar 31, 2012
26,398
I don't understand the following things related to the question.

1) What is the reference voltage of DAC's (n bit R/2R).
2) How to find the number of bits in this DAC.
3) how to set reference voltage of ADC by using a DAC.

I tired find theories related abouve questions and found nothing. So I could not do anything to solve these.
What material do you have that is part of this course? What text are you using?

What have you learned about DACs and ADCs in general?
 

Thread Starter

thar07

Joined Jan 3, 2015
71
@thar07 :) By the way are you a student of OUSL?
Yes. Are from galle center?

What material do you have that is part of this course? What text are you using?

What have you learned about DACs and ADCs in general?
I refer "The 8051 Microcontroller and Embedded systems" book as the material.
I have not learn much about them, only the basics.
If you could please give me theory notes related to this.
 

isurunix

Joined Feb 3, 2015
21
Draw a block diagram to interface an 8 bit ADC with 8051. Clearly show your calculations
and assumptions to use above DAC to set the ADC reference voltage 10 V and display the
result in three seven segment displays.

Can anyone help me with getting this done. What I understood so far is as followes

Block Diagram

Selection_001.png
Calculations for setting the reference voltage


Output = 10V
Input = 10/15.625*10^-3 = 640
Input digital signal = 1010000000

I can understand that I have to send the input signal to the DAC discussed here using the 8051 and I can use Vout of the DAC as the reference for ADC

What I cannot understand is what is meant by displaying the value in 7 segment displays ( What do I have to display ? ) and what are the required calculations and assumptions.

I'm posting this here as this thread has an ongoing discussion about the DAC used here. If this qualifies as a separate question please notify me and I'll start a new thread
 

WBahn

Joined Mar 31, 2012
26,398
It probably should be a different thread since this thread is the OP's thread regarding HIS work on this problem. But that's just my take.

I would imagine the idea is to display the voltage on the 7-segment displays. Think of it as making a voltmeter.
 

WBahn

Joined Mar 31, 2012
26,398
Do I have to display a decimal value or a binary value on the displays?
How should WE know? It's YOUR assignment!

But consider that you are to display the result on THREE 7-segment displays. Your resolution isn't going to be very good if you try to display the voltage in binary, is it?

Again, think of this as making a voltmeter. Would you want a voltmeter that displays the measured voltage in binary?

What makes the most sense?

If you have a 10V reference and a 10-bit ADC and three 7-segment displays to work with, what makes the most sense? What value do YOU think should be displayed when the input voltage is 5V?
 

isurunix

Joined Feb 3, 2015
21
Assignment doesn't say anything explicitly on what should I display. Thats why i'm confused. And I'm only having a 8 bit ADC.
 

WBahn

Joined Mar 31, 2012
26,398
Assignment doesn't say anything explicitly on what should I display. Thats why i'm confused. And I'm only having a 8 bit ADC.
So same questions. What makes sense to YOU?

Or ask your instructor. Why would WE be able to understand what YOUR instructor wants? At least YOU have some context within which to interpret the assignment -- WE don't.
 

isurunix

Joined Feb 3, 2015
21
I'm constantly trying to contact the instructor. But unfortunately universities moodle site is down and damn telephone lines are not been answered. Any way I found this site and it contains lot of information. Thought it's worth mentioning here.
 
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