Orbital6
Posts: 140
Joined: Sat Aug 08, 2015 6:32 pm

Thoughts on a completed ADC HAT + Advice / feedback welcome

Fri Mar 31, 2017 2:03 pm

Hi,

Some time ago i finished a pi-zero sized 'HAT' for a functionality i've noticed isn't on sale at major pi distributors.

tl;dr It's a low-cost low-noise ADC pHAT with both a line-in jack and a mic jack w/ pre-amp, with the ability to mix both sources; so basically instead of all those noiseless DACs on the market, this takes IN audio at 24bits, 96 KHz. There's an additional breakout for extensions, left to the discretion of the maker/end-user. Additionally, a software script allows for a one-click install.

(right click and open in a new tab to get the full resolution).

Image

Older version with reflow soldering

Image

It has optional power sources, including USB for people who are really picky.

I don't know how to take this further, I've tried sending a letter to pimironi to ask if they had any interest in distributing it, but was quite disappointed to hear zilch back.

So I'd love to hear what this community thinks in terms of:

* If you think there would be demand for such an add-on
* Are the built in features enough for what you may want out of it
* general nerdy comments and advice
* How to go about commercialising / distributing it

I'm excited to hear what your thoughts are. I don't think the price would be north of £20 - £25, more expensive than a phat dac obviously but many more components here.

Thanks!
Last edited by Orbital6 on Fri Mar 31, 2017 5:34 pm, edited 3 times in total.

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mikronauts
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Re: Thoughts on a completed ADC HAT + Advice / feedback welc

Fri Mar 31, 2017 4:44 pm

Hi,

The links/pics/price were missing from your post.

Regarding marketing it, try Ebay and Tindie to start with.
http://Mikronauts.com - home of EZasPi, RoboPi, Pi Rtc Dio and Pi Jumper @Mikronauts on Twitter
Advanced Robotics, I/O expansion and prototyping boards for the Raspberry Pi

Orbital6
Posts: 140
Joined: Sat Aug 08, 2015 6:32 pm

Re: Thoughts on a completed ADC HAT + Advice / feedback welc

Fri Mar 31, 2017 5:31 pm

mikronauts wrote:The links/pics/price were missing from your post.

Regarding marketing it, try Ebay and Tindie to start with.
Thanks a lot Mikronauts, it seems the photos worked on my browser but you were totally right, switched servers now.

I could try Tindie, i didn't think many people look at ebay for unique boards though?

Regarding price, i can't see it being more than £20 - £25.

What other information would help do you reckon?

hystrix
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Re: Thoughts on a completed ADC HAT + Advice / feedback welc

Thu Apr 27, 2017 11:52 am

If the sample rate was 192 kHz it would be an ideal "replacement" for the now apparently discontinued Cirrus Logic Audio Card. With that board no longer available, the only other alternative is the older Wolfson Audio Card, which doesn't fit the latest Pi versions without some tinkering.

Now if it could sample at 384 kHz, you would make people who want to record ultrasound (e.g. bats) very happy indeed :)

There is definitely a market for a high resolution HAT for recording audio - that feature is lacking in almost all current audio cards, or is limited to 96 kHz sample rate.

wm6h_1
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Joined: Sat Dec 26, 2015 1:16 pm

Re: Thoughts on a completed ADC HAT + Advice / feedback welc

Thu Apr 27, 2017 12:28 pm

Would this give that much better performance than the standard (cheap) USB sound cards? They are 16-bit 44.1-48 ksps. Wouldn't there be enough noise floating around on a Raspberry Pi that 16 vs 24 bits would be rather moot?
Follow your dream but do you have some performance figures v. much less expensive alternatives?

Orbital6
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Re: Thoughts on a completed ADC HAT + Advice / feedback welc

Thu Apr 27, 2017 12:46 pm

wm6h_1 wrote:Would this give that much better performance than the standard (cheap) USB sound cards? They are 16-bit 44.1-48 ksps. Wouldn't there be enough noise floating around on a Raspberry Pi that 16 vs 24 bits would be rather moot?
Follow your dream but do you have some performance figures v. much less expensive alternatives?
I could do some comparisons. What would you be interested in?

The idea is you this is very low noise (hiss), uses the pcm peripheral native to the bcm IC, and keeps your usb ports free.

As far as i know, there aren't cheap alternatives that use the pcm peripheral. Like the poster before said, the wolfson card did the same thing but full duplex, but was £150ish.

This is a cheap easy solution to get high quality audio into the pi, should you want mic input (something i see a lot of people struggling with) or line in audio, with the option to mix the two.

The idea of having ridiculously high sample rates wasn't on my mind given this was developed for audio, and not as a pure adc for sensors etc that may need that.

texy
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Re: Thoughts on a completed ADC HAT + Advice / feedback welc

Thu Apr 27, 2017 1:39 pm

I had a lot of success selling my 2.8" display boards via this forum and eBay. I got close to securing a deal with a pi distributer, but they went the Adafruit way in the end - difficult to beat the big boys :) and by that time the Chinese were making there own clone Pi TFT displays and it just wasn't worth competing with their prices.
However my design was all through hole and each module could be knocked up in 5-10 minutes. As yours is SMT, I would look at one of the PCB fab houses that also specialise in assembly.
Hope this helps,
Texy
Various male/female 40- and 26-way GPIO header for sale here ( IDEAL FOR YOUR PiZero ):
https://www.raspberrypi.org/forums/viewtopic.php?f=93&t=147682#p971555

hystrix
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Re: Thoughts on a completed ADC HAT + Advice / feedback welc

Thu Apr 27, 2017 4:10 pm

Orbital6 wrote: As far as i know, there aren't cheap alternatives that use the pcm peripheral. Like the poster before said, the wolfson card did the same thing but full duplex, but was £150ish.
The Wolfson card is £16.50 before UK tax. https://www.element14.com/community/com ... wolfson_pi

If I recall correctly, the later Cirrus Logic Audio Card was a bit more expensive, but not much; maybe £30 including tax.

KanoMaster22
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Re: Thoughts on a completed ADC HAT + Advice / feedback welcome

Wed Jun 27, 2018 11:38 pm

Any news on this board? It looks promising.

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