Making a 12 bit DAC Using an Arduino -- The Learning Circuit 96

Making a 12 bit DAC Using an Arduino

The Learning Circuit | element14 presents | Project Videos

Once analog signals have been processed by electronics and converted to digital, to convert them back to analog, a DAC is needed. In this video, Karen shows how to make an R-2R Ladder DAC using just resistors, all of the same value. The ladder uses 12 of the digital I/O on an Arduino Uno as its inputs. While the Ladder DAC will be 12-bit, Karen is able to use it to show the differences in resolution between a 4-bit, 6-bit, 8-bit, and 12-bit DAC, generating a sine wave as a visual demonstration.

Bill of Material:

Product Name	Manufacturer	Quantity	Buy KitBuy Kit
Through Hole Resistor, 1 kohm, 500 mW, ± 1%	TT ELECTRONICS / WELWYN	36	Buy NowBuy Now
Breadboard, MCM 60 rows, ABS, 8.5mm, 165mm x 56mm	MULTICOMP	1	Buy NowBuy Now
Arduino Uno SMD, ATmega328 MCU	Arduino	1	Buy NowBuy Now
Wire Kit, Jumper, Male to Male, Solderless, 100 mm - 250 mm, 75 Piece	MCM	1	Buy NowBuy Now
MULTICOMP PRO USB Cable, Type A Plug to Type B Plug, 0.91 m, 3 ft, USB 2.0, Beige	MULTICOMP PRO	1	Buy NowBuy Now

Additional Parts:

Product Name
Computer for programming

Top Comments

DAB over 4 years ago +1

Very good episode Karen. You did a great job of showing ADC resolution issues and how they affect the information you can pull out of an analog circuit. DAB

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koudelad over 4 years ago

Nice video including the output presentation.

One question - how is it possible that using 4 bits there are only 4 visible voltage values (I would expect 16 steps including 0 V) and using 6 bit there are 16 voltage values (I would expect 64 including 0V)?
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makerkaren over 4 years ago in reply to koudelad

I'm not exactly sure which part you're talking about. But, while a 4-bit DAC has a resolution of 16, we only see 4 bits of data. Each bit can be high(on) or low(off). Doing the math for the possible combinations of each bit being on or off, we get 16 possibilities.
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makerkaren over 4 years ago in reply to koudelad

I'm not exactly sure which part you're talking about. But, while a 4-bit DAC has a resolution of 16, we only see 4 bits of data. Each bit can be high(on) or low(off). Doing the math for the possible combinations of each bit being on or off, we get 16 possibilities.
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koudelad over 4 years ago in reply to makerkaren

At 5:04 at the video, you adjust the code to 4 bit resolution of the DAC. However, at 5:20, there are only 4 voltage levels. That is where I would expect to see 16 voltage levels, as you described.

At 5:29 the code is adjusted to 6 bits, which should produce 64 different voltage level, however, I can only see 16.

Or maybe I got something wrong...
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makerkaren over 3 years ago in reply to koudelad

That's.....a really good point. I'm not really sure. I'd have to have someone that knows Arduino code better than I, take a look at the code and see if there's anything that is reducing the visual output. But yeah, you're right. It looks like there are fewer steps than the full resolution each time. Hmmmmm.
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Hillary over 2 years ago in reply to makerkaren

Hello! I actually tried this project and had so much fun testing it. I managed modified your code a little, you can check it out on my github: https://github.com/HillaryatGitHub/Multiple-Bit-DAC. Again thank you so much for making such an in depth video
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