Jump to content

New AOUT module design?


TK.
 Share

Recommended Posts

  • Replies 97
  • Created
  • Last Reply

Top Posters In This Topic

From the "Making sound with a Core" thread:

Well, I'm just working on the same project, but I use a AVR instead of a PIC. The way with PWM is nice and cheap. If you use a big Cap on the output, you can also use the pwm modulation amount as direct analog DAC output. Soundgin and Speakjet do it exactly that way.

???

Link to comment
Share on other sites

About CANANA: This is really a whole system with own processor that is communicating via CAN. Doesn´t seem as if you can buy it, and it would be quite expensive.
Ah, I see.  I was mostly putting it out there because of the DACs they use.
AD539x series ... 14-Bit DACs have around +/-1 LSB INL (!) - that´s even better than the 525 :) It has a cascadeable serial interface, too. ...  AD5392 8 channel version that is available at Farnell for 33 EUR +VAT.

That seems a pretty good price for the specs!  Pity about the tiny pins but maybe it's workable?

Cascadeable serial - does that mean it can be fed from one/two PIC pins?

16 channels would be a bit overkill and if all 16 channels get their OpAmps etc., everything wouldn´t fit onto a 80x100 mm board.
Could the opamps be moved to another board?  Or some of them?  IE a 4 or 8 channel implementation with optional plug in opamp board?

Link to comment
Share on other sites

That seems a pretty good price for the specs!  Pity about the tiny pins but maybe it's workable?

You can be the beta tester!

Cascadeable serial - does that mean it can be fed from one/two PIC pins?

2-3, Just check the datasheet out.

16 channels would be a bit overkill and if all 16 channels get their OpAmps etc., everything wouldn´t fit onto a 80x100 mm board. Could the opamps be moved to another board?  Or some of them?  IE a 4 or 8 channel implementation with optional plug in opamp board?

I don´t know. 4 x SOIC OpAmps don´t cost that much space.

Moebius

Link to comment
Share on other sites

  • 2 months later...

...

Just sticking my head in here, once I've got some time available I'm def. interested in helping here in whatever way possible (I won't have real time to help for a couple months still).  Perhaps we can split up the work based on different designs and compare results etc. 

But the AD539x series has really great specs - the 14-Bit DACs have around +/-1 LSB INL (!) - that´s even better than the 525 Smiley It has a cascadeable serial interface, too. The only problem would be the LQFP package with 0.65 mm pin distance  Undecided 16 channels would be a bit overkill and if all 16 channels get their OpAmps etc., everything wouldn´t fit onto a 80x100 mm board. But there´s the AD5392 8 channel version that is available at Farnell for 33 EUR +VAT. So maybe this one is worth some discussion - Thorsten??? Smiley

This is the chip that interests me the most.  I agree that 8 channels per board is plenty and the small lead spacing doesn't present a problem IMO.  Granted this wouldn't be a good project for a beginner, but once you know how to work an iron .65mm is workable.  Without digging too deep into the documentation it does seem to provide a good replacement for the 525.  Looks like it only does 0-5v which is regrettable, but we can't exactly be choosy..  They're not exactly highly available either, but digikey has them for ~25$  Not too bad.

Link to comment
Share on other sites

Just sticking my head in here, once I've got some time available I'm def. interested in helping here in whatever way possible (I won't have real time to help for a couple months still).

as stated here http://www.midibox.org/forum/index.php?topic=8494.msg63092#msg63092, the next couple of months the project is on hold anyway.

Perhaps we can split up the work based on different designs and compare results etc.

Help is always welcome :) But I think we already have two AOUT modules now, so designing more than one new version would be rather confusing. I think we (before all others TK!) should decide for one DAC and then make one good design. I´ve got some experience with layouts and digital design, but am lacking some more in-depth insight to high quality analog/opamp cirquits. So if you can do research on opamp designs and find out if there are even better ways than the TL0xx design on the old AOUT, that would be really great!

(AD5392)

Looks like it only does 0-5v which is regrettable, but we can't exactly be choosy..

The MAX525 is also "only" 0-5V. With the output opamps you can do both 0-15V and +/- 15V depending on the setup. Is there a problem with 0-5V I´m not aware of?

They're not exactly highly available either, but digikey has them for ~25$  Not too bad.

Digikey doesn´t stock them, minimum order is 15 pieces IIRC. But perhaps we could talk SmashTV and/or Mike into selling them together with the boards. But as mentioned before, it´s probably a bit early talking about such details.

Seppoman

Link to comment
Share on other sites

Help is always welcome Smiley But I think we already have two AOUT modules now, so designing more than one new version would be rather confusing. I think we (before all others TK!) should decide for one DAC and then make one good design
.

Roger that, my thought was simply that we may find a gap between datasheets and real world performance.

I´ve got some experience with layouts and digital design, but am lacking some more in-depth insight to high quality analog/opamp cirquits. So if you can do research on opamp designs and find out if there are even better ways than the TL0xx design on the old AOUT, that would be really great!

I can certainly handle that.  I don't think we're going to find any major revelations given that were working with really low frequencies, but there are probably optimizations in terms of offsets and small errors here and there that will give less savvy builders headaches.

.. and unless I'm retarded (possible) digikey has both 5392 and 5391 in stock with no minimum, were you planning on ordering samples or should I buy a couple?  AD's sample policy has tightened up quite a bit recently so we may be right back to square one in terms of availability in the US if DK doesn't keep them in stock.

Link to comment
Share on other sites

.. and unless I'm retarded (possible) digikey has both 5392 and 5391 in stock with no minimum, were you planning on ordering samples or should I buy a couple?  AD's sample policy has tightened up quite a bit recently so we may be right back to square one in terms of availability in the US if DK doesn't keep them in stock.

Digikey has only the BCP types in stock, that´s the LFCSP package  :-\ The BST version (LQFP) is non-stock.

I´ve successfully ordered samples (ssm2164) some months ago, so I´ll try to get some DACs as samples first before spending any money.

Seppoman

Link to comment
Share on other sites

OK so we can only sample 5391-bst3 (not the lower LSB -5) but what about the 5391? Should I try for BST-3, BST-5, BSTZ-3, or BSTZ-5?

Edit: Hey guys seeing as they are tight with samples don't everyone try at once. I am in a certain position which means that I am very likely to get some, which I will then share around... It's early days yet, you won't miss out :)

Link to comment
Share on other sites

Hi,

too late :)

  Product    Total Quantity    Available to Ship Date*    Estimated Delivery Date    Unit Price

AD5392BSTZ-5                  2                  04/03/2007                        04/10/2007                  No Charge 

8-Chn 5V Single Supply 14-Bit Vout I.C.

Let´s see how it works out. I also noticed that the ssm2164 is not available for sampling anymore, so they definitely cut down the sampling program a bit. But I´ve also got a confirmed account so hopefully there won´t be a problem.

About the types: the -3 or -5 at the end is the supply voltage, so we need -5! the Z stands for lead-free, so it´s not important to us.

Seppoman

Link to comment
Share on other sites

Damn, no online samples for us down under >:(

Huh? How do you come to that conclusion? I even tried selecting the Australian Analog site, they also have the "Add to cart" sign with the AD5392BSTZ-5. Did you call the Australian office directly?

I´ve ordered through the normal analog.com site. Go here: http://www.analog.com/en/prod/0%2C2877%2CAD5392%2C00.html, second last line second rightmost column :) Even got the acknoledgement for my order in the meantime :) There´s no note that Australia is excluded from the sample program.

Seppoman

Link to comment
Share on other sites

  • 2 weeks later...
  • 1 month later...

Hi guys,

just wanted to give a sign of life about this project - I was quite busy in April and then on vacation, but now am resuming work on the AOUT. I´ve done an Eagle part definition of the AD5392 and thought a lot about the analog part of the board. At the end, there were no real revelations on cirquit design. The board will most likely contain bipolar option selectable through jumper/bridge for each channel. As the AD5392 has a way to adjust offset trim via software, for the bipolar option it will only be necessary to add four resistors to the relevant channels. It would also be possible to adjust gain via software, but TK pointed out that probably a lot of people like the analog feeling of a precision trimpot better.

Anyway, I´m working on this now, am hoping to get a working board until summer and then send one to Thorsten. So don´t expect anything final before autumn :)

Seppoman

Link to comment
Share on other sites

Is there a S&H board in the works too? (Just for all of us interested in lots of channels who can't find the SHX8 IC's)

For me, designing one new board at a time is enough :) (I´m also doing other boards right now, but nothing else MBHP-related). But maybe someone else wants to jump in here?

Seppoman

Link to comment
Share on other sites

I posted about the shx8 problem in another thread, but have not yet found a response.

So i'll repeat it here:

I stumbled upon a comparable chip from Analog Devices, the SMP08 (or SMP018):

http://www.analog.com/en/prod/0,,773_925_SMP08%2C00.html

The truth table is the same as and it's an all in one chip like the nju.

It is not cheap, but not much more expensive than the nju either.

With my limited knowledge it looks like a good replacement.

So if the knowledgeable people here agree, i would try it out and do my best to do a pcb design around it.

Browsing for parts it seems that there are lots of solutions that

combine a dac and a multiplexer with s&h.

But there do not seem to be many nju - like solutions around.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
 Share


×
×
  • Create New...