VS1063a with external DACs

Designing hardware that uses VLSI Solution's devices as slave codecs such as an external MP3 decoder chip for a host microcontroller.
HeinrichG
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VS1063a with external DACs

Post by HeinrichG » Mon 2011-08-29 1:06

Hi Guys,

at the moment I'm developing an high-end player as add-on for the radio. The radio is an Audi Concert 1 and I would like to replace the tape deck by this add-on. On add-on card is an LPC1769 MCU from NXP, a hard drive which is connected throw sata-> usb adapter to the mcu. Then VS1063a is connected throw spi interface to the mcu.

I would like to use an external DAC, WM8741 in dual differential mode. This means one of them is for left channel and the second is for right channel.

The I²S interface of VS1063 has an fixed word length of 16 bits and variable bit rate, between 48kHz and 192kHz. It is possible to change the word length from 16 bit to 24 or 32?

I looked for SRC, but I didn't find one which is able to do this.

Thanks & regards,
Heinrich
Regards,
Heinrich

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Panu
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Re: VS1063a with external DACs

Post by Panu » Wed 2011-08-31 19:10

Sorry, the VS1053/VS1063 I2S hardware is fixed to 16 bits/sample (32 x Fs bit clock).

There's a discussion about the subject in this forum at: viewtopic.php?f=10&t=398&p=1467 and viewtopic.php?f=9&t=32 .

-Panu
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Re: VS1063a with external DACs

Post by HeinrichG » Wed 2011-08-31 22:04

Hello Panu,

thanks for the fast answer. In this case I can't understand VLSI, the VS1053 and VS1063 are really nice decoder-ics, but I²S-interface is not the best. It's really pity. STA015 (ST) can be configured between 16 and 24 bit. :( Okay, it's just a mp3-decoder.

Kind regards,
Heinrich
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Heinrich

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Panu
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Re: VS1063a with external DACs

Post by Panu » Thu 2011-09-01 8:01

Yes, in VS1053/VS1063 hardware (they are the same platform) the I2S output was a quick add-on to the existing DAC architecture for some customer request which was pressing at the time. But in VS1005 we've had time to redesign the I2S port so it's much more flexible.

The good thing about the I2S output in VS1053/VS1063 is that it's completely hardware implemented and runs in the background so you get the I2S output for "free".

-Panu

PS. you do have some options regarding this... pls read the other threads :)
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Re: VS1063a with external DACs

Post by HeinrichG » Fri 2011-09-02 11:58

Hi Panu,

I read something about VS1005 in some threads here, but didn't find some information about release date or something else. Is this chip in development in the moment?

Is the I²S interface of VS1033 the same like in VS1063, so can I use the note "interfacing dac to VS1033" for VS1063 too?

Thanks & Regards,
Heinrich
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Heinrich

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Panu
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Re: VS1063a with external DACs

Post by Panu » Sun 2011-09-04 8:42

Hi!

Yes, the VS1005 chip is in development, we have already have some internal engineering samples. I'm writing an OS framework for the VS1005 currently. The I2S port of VS1005 is an independent peripheral, so it can be controlled freely.

VS1033 is one step older generation than VS1053 and VS1063, but from the looks of the appnote (http://www.vlsi.fi/uploads/media/vs1033an_i2sdac.pdf), it seems similar to VS1053/63. So I'd give good chance that the same procedure is going to work.

-Panu
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Re: VS1063a with external DACs

Post by HeinrichG » Mon 2011-09-05 9:22

Hello Panu,

can you say me the release date of VS1005? So, if it's not so far away, I can wait for it and use them in my player.

I compared the description of I²S from VS1033 and VS1063 and it looks very similar. So I'll just use the app note from VS1033.

Thanks & Regards,
Heinrich
Regards,
Heinrich

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Re: VS1063a with external DACs

Post by pasi » Mon 2011-09-05 11:47

HeinrichG wrote:Is the I²S interface of VS1033 the same like in VS1063
The pins have been reassigned to different GPIO pins, so you have to change which GPIO's to configure as outputs (and where to connect). But the operation is identical.
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Re: VS1063a with external DACs

Post by HeinrichG » Thu 2011-09-29 9:29

So, I have a new short question, if I'm not using the analog outputs of VS1063, what I have to do with them?

Just leave them open or something else?

Then, which ASRC ist besser for using with VS1063, CS8421 or AD1896? The guys from http://www.head-fi.org are prefering CS8421.

Thanks & Regards,
Heinrich
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Heinrich

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Re: VS1063a with external DACs

Post by pasi » Fri 2011-10-07 20:55

HeinrichG wrote:if I'm not using the analog outputs of VS1063, what I have to do with them?
It is best if you have the resistor+capacitor to ground to keep everything stable, even if you don't use the outputs. If you have space issues, you can leave the outputs floating. If you use analog inputs you need the RCAP capacitor as well. If you don't use the analog inputs, you can leave them unconnected.

If you don't use analog outputs, you can reduce the I2S headroom by using the SWING bits in the STATUS register. (Only +0.5dB increase is possible when DAC is used or the modulator will overflow with full-scale signals.)
HeinrichG wrote:Then, which ASRC ist besser for using with VS1063, CS8421 or AD1896?
I don't really know. I hear that very few external DAC's nowadays actually follow the I2S spec (they are more like generic SPI devices when it comes to the operation of the left/right signal and do not automatically adapt to the number of data bits), so selecting one that does is the first priority :-)

Depending on the application I would like to encourage you to also evaluate the built-in DAC's of vs1053/vs1063. Comparing specs may not give you the full picture without suitable interpretation of the figures. :-)
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