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Project14 | Data Conversion: From ADCs to DACs, Explore A-D or D-A Techniques!

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Data Conversion

Enter Your Electronics & Design Project for a chance to win a $200 shopping cart!

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Monthly Themes
Monthly Theme Poll

 

In the Comments Below:  Let Us Know Project Ideas around Data Conversion!

 

Your projects can explore either A-D or D-A techniques, or improve them in terms of increasing speed, resolution, linearity, reduction of noise or filtering of the analog signal.

 

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Monthly Theme

The January theme is  Data Conversion and it was inspired by a suggestion from  . Your projects can explore either A-D or D-A techniques, or improve them in terms of increasing speed, resolution, linearity, reduction of noise or filtering of the analog signal.   Analog electronics and precision measurement are important for ADC and DACs.  element14 Essentials: Analog Electronics 1 gives a good primer on this topic and it covers key parameters, characteristics, and applications of precision measurement analog ICs, including ADCs, DACs, voltage references, op-amps, audio amplifiers, and current sense amplifiers. .image

 

Projects  suggest you could explore include the unique uses for ADC or DAC (e.g. capture something unrelated like light intensity to tell time of day) or comparisons (e.g.  capabilities of microcontroller built-in ADC or DAC to dedicated components).   You could convert from one quantity to another such as converting sound to light level (ADC the sound, DAC the light level).   You could also DIY ADC or DAC (e.g. can you build your own Sigma-Delta converter using 7400-series chips?) or demonstrate the importance (or non-importance) of Bits (eg. built circuits that show the difference between 8-bit and 10-bit ADCs. or 14-bit and 16-bit DACs). Does one matter more than the other?). Finally, you could work on circuits or projects that use a DAC or ADC, but not a microcontroller.

 

Some examples of projects came up with include data acquisition and charting (Brewing beer with Raspberry Pi)  ; seismology (TI LDC1000 Evaluation Module ) ; switched capacitor, and sample and hold based circuitsswitched capacitor, and sample and hold based circuits;  detecting sounds (Vibration Sensor and Exercising - Calculating FFT on Nucleo Board - Blog #3 ); signal generation (Building A Direct Digital Synthesis Dual-Channel Signal Generator );  medical sensing (MagicHat - 6 - Heart beat detection );  power monitoring (Turn your Avnet Azure Sphere Starter Kit into a Power Meter / Data Logger ), software defined radio (Software Defined Radio (SDR) - My First Design ), and distance learning (Virtual Eye System -- Post#4 -- Programming the Pi to get the distance ).   Projects can involve ADCs or DACs, or analog data could be sampled or filtered or converted to a different domain, signals could be extracted or synthesized, speech processing, instrumentation, SDR and so on.image

 

Key Dates:

 

EventDate
Competition Opens:15th January 2021
Competition Closes:15th March 2021
Winners Announcement:24th March 2021

 

 

Project Ideas

Here are some projects to help inspire you:

 

Brewing beer with Raspberry Pi by :

 

Brewing beer with Raspberry Pi
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Vibration Sensor and Exercising - Calculating FFT on Nucleo Board - Blog #3 by :

 

Vibration Sensor and Exercising - Calculating FFT on Nucleo Board
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MagicHat - 6 - Heart beat detection by :

 

MagicHat - Heart beat detection
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Turn your Avnet Azure Sphere Starter Kit into a Power Meter / Data Logger by :

Turn your Avnet Azure Sphere Starter Kit into a Power Meter / Data Logger
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Software Defined Radio (SDR) - My First Design by :

 

Software Defined Radio (SDR) - My First Design
imageimage

 

Field Strength Meter by :

 

Field Strength Meter
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Virtual Eye System -- Post#4 -- Programming the Pi to get the distance by :

 

Virtual Eye System -- Programming Pi to get the distance
imageimage

 

Vector Display GPU Project  by :

 

Vector Display GPU Project

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Project Outline: LaserScope Music by :

Project Outline:  LaserScope Music

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A simple frequency response analyser by :

A simple frequency analyser

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Building A Direct Digital Synthesis Dual-Channel Signal Generator by :

Building A Direct Digital Synthesis Dual-Channel Signal Generator

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Your Chance to Win

 

Be Original
Stick to the Theme
  • You could come up with a clever name that make's your project memorable!
    • This project is your baby! Part of the fun of bringing something new into the world is coming up with a name.
  • Your project could introduce something new or that is not commercially available or affordable!
  • If you have an idea for a project that doesn't fit the current theme then submit your idea in the comments section of the monthly poll.
List the Steps
Submit Video Proof
  • Provide the steps you took to complete your project (text, video, or images).
    • This could be a step by step how-to-guide, vlog, schematics, coding, napkin drawings, voice narration, or whatever you think will be useful!
  • If it doesn't work that's fine, this is more about the journey than the end product.
  • A short video is all that is required but you can shoot as much video as you like.
  • You are encouraged to be creative and have as much fun as possible!

 

Your Project Examples

 

Making Time
Building A Direct Digital Synthesis Dual-Channel Signal Generator Vector Display GPU Project

 

 

 

Your Prizes

 

One Grand Prize Winner Wins a $200 Shopping Cart!Three First Place Winners Win a $100 Shopping Cart
  • One Grand Prize Winner Wins a $200 Shopping Cart!
  • 3 First Place Winners a $100 Shopping Cart!
imageimage

 

Some Terms & Conditions Apply:  How to Redeem Your Shopping Cart for Project14

 

Your Project, Your Ideas!

 

About Project14
Directions

Every month you'll have a new poll where you'll get to decide an upcoming project competition, based on your interests, that will take place a couple of months in advance. Themes are broad in scope so that everyone can participate regardless of skill set.

 

What are Monthly Themes?

  • Every month (around the 14th of each month) a new theme will be posted on Project14.
  • Submit your ideas (proposals) for your projects to get feedback from the rest of the community.
  • Submit a project entry in the Theme space once you start working on it.

 

What are Monthly Theme Polls?

  • Every month (around the 14th of each month) there is a project theme poll.
  • Vote on which project competition you want to see for the following upcoming theme.
    • The themes voted on during the previous poll decided the upcoming theme.
    • If you submit an idea for a theme that is not used then it can still be used in a future poll.
  • Themes comments and ideas from the comments section of the project theme poll.

Step 1: Log in or register on element14, it's easy and free.

Step 2: Post in the comments section below to begin a discussion on your idea. Videos, pictures and text are all welcomed forms of submission.

Step 3: Submit a blog post of your progress on your project by the end of the month.  You are free to submit as many blog entries as you like until the beginning of the next theme.

 

Be sure to include video proof of your project!

 

Visit:   Data Conversion or tag your project blog DataConverCH

 

You have until March 16th End of Day to submit your completed project!

 

 


 

 

A jury consisting of your peers will judge project submissions!

 

 

In the Comments Below:  Let Us Know Project Ideas around Data Conversion!

  • in reply to Jan Cumps

    ... I'm going to submit the simple project without GaN amplifier. The project can then be replicated with an Arduino UNO.

    The GaN power stage can be a separate post in the power electronics area.

    Done. DAC: Class-D signals

  • in reply to Jan Cumps

      wrote:

     

    ...In essence, this is a class-D amplifier, if you consider the I/O output push/pull pair as a half-bridge...

    I'm going to submit the simple project without GaN amplifier. The project can then be replicated with an Arduino UNO.

    The GaN power stage can be a separate post in the power electronics area.

  • A completely analog circuit to drive a 16x2 LCD. Usually, a 16x2 LCD is interfaced with a microcontroller. But in my project submission, I plan to display data on the LCD without using a controller. It will display data from a LM35 temperature sensor.

  • in reply to Jan Cumps

    Here's the outcome after a low-pass filter:

    image

    In essence, this is a class-D amplifier, if you consider the I/O output push/pull pair as a half-bridge...

     

    image

  • in reply to jc2048

     

    Is that the integrated one with the drivers built in? Does it save you from yourself if you get the drive signals overlapping, or are you going to have to be very, very careful how you set up the PWM signals to make sure there's a deadband at all times?

    I have a TI GaN evaluation kit, that generates a correct deadband on board. It uses NOT gates, capacitors and diodes for that.

    That board can be driven with a single PWM.

     

    My home-made one does not have this circuit (on purpose: I made it to see if I could use the Hercules controller programmable timers to generate 10 ns deadband).

    If I use that one as end stage, I'd need to build similar hardware as on the TI kit to generate it. Or use that same Hercules timer to generate complimentary signals with the deadband out of box.

    That should be possible, because I'm using that module in my proposal to create the d-class style signals (WIP - the scope capture below of a sinus pulse train is the effort of today's work)

    image

  • in reply to Jan Cumps

    Is that the integrated one with the drivers built in? Does it save you from yourself if you get the drive signals overlapping, or are you going to have to be very, very careful how you set up the PWM signals to make sure there's a deadband at all times?

  • in reply to Jan Cumps

    The op amps will reject a proportion of the rail noise, though not as much as the headline PSRR figure would lead you to believe, but they don't even know that a difference between ground references in different places is not just part of the real signal. I don't pretend to understand how this all is best done (unfortunately, I don't have a history of analogue design), but it seems to me that they are things to be careful of and worth some experimenting with.

  • in reply to jc2048

     

    I'm worried the noise on that rail would be too much for the OP-amp to handle, even with a high PSRR

      used a capacitor switcher on the programmable load to generate the negative rail for the analogue stuff. You need to keep the ground quite solid and be careful how you route it - I could see some noise between the grounds of two of the boards that derived from the switching edges. If you want to get an idea of what it would be like, perhaps Jan or myself could do you some traces from the programmable load.

     

    If the negative rail doesn't need to be too accurate, you could do the capacitive switcher yourself using a PWM output from the processor. The advantage of that would be that you could stop it momentarily and let the circuit coast on the bulk decoupling capacitor to get the rail as quiet as possible during the conversion. Alternatively, given how fast the conversion of a SAR is compared to the 10kHz switching, you could sense the switching clock and simply position the conversion well away from the edges.

     

    It's not a super noise-free design. The artifacts of the switcher can be found back on all rails.

    An additional inductor and better PCB design would help.

     

    An external nput of 12 V DC is used as a rail, and also as a source for + and - 5 V:

    The +5 V is delivered by a LM7805LM7805 linear regulator. The -5 V by the capacitive charge pump LM2662LM2662.

    image

     

     

    As external reference, a 2.048 V TI REF5020TI REF5020:

    image

  • in reply to ajcc

    Sounds like an interesting project you're working on.

     

    I'd also want a better voltage reference than the 5V rail from USB (less noise!).

    As well as being able to use Vdd or an external reference, the processor on the UNO has an internal 1.1V voltage reference that can be selected. I know that because I used it for something, though I can't quite remember what it was. If I remember or come across it, I'll put a link here.

     

    I'm worried the noise on that rail would be too much for the OP-amp to handle, even with a high PSRR

    used a capacitor switcher on the programmable load to generate the negative rail for the analogue stuff. You need to keep the ground quite solid and be careful how you route it - I could see some noise between the grounds of two of the boards that derived from the switching edges. If you want to get an idea of what it would be like, perhaps Jan or myself could do you some traces from the programmable load.

     

    If the negative rail doesn't need to be too accurate, you could do the capacitive switcher yourself using a PWM output from the processor. The advantage of that would be that you could stop it momentarily and let the circuit coast on the bulk decoupling capacitor to get the rail as quiet as possible during the conversion. Alternatively, given how fast the conversion of a SAR is compared to the 10kHz switching, you could sense the switching clock and simply position the conversion well away from the edges.

     

    Addendum

     

    I realised after I'd written the above that I'd forgotten that processor SAR A/D converters normally have a sample and hold ahead of them, so it's the period in the run-up to the sampling and whilst it's going on where you want things nice and quiet.

     

    This was the project where I used the 1.1V reference, in case it helps: Simple NANO Battery Tester Prototype

  • I'm thinking about building a class-D amplifier with GaN fets.

    I have a home made GaN half-bridge.

    The missing parts are:

    • Prepped "digital" input signal
    • A circuit to generate opposite pulse trains with a short dead time from the signal
    • Low pas filter.

    In all fairness, this isn't digital as in "bits and bytes".

    But it's a circuit that works with signals that are only 1or 0 up to the filter ...