Re: [LAU] open hw soundcard

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To: <linux-audio-user@...>
Date: Sunday, November 15, 2009 - 9:54 pm

Folderol:

...

The chip select comes with the spi bus interface, which(s) chip shall
respond to the clock.

> and also a count overrun, both of which

That is normal for chips with spi bus.

> It also has an interesting feature of having it's own high

Some has an internal clock and some need an external. At most this will
affect component count.

> so presumably, once a conversion has been

It doesn't seem to be an easy way to sync TLC4545ID's. The sampling
start after 5 clcks after chip_select, it need another 20 clcks for the
sampling. Then you release the chip and it will convert the analog value
to digital and it takes < 2.94us. During the sampling time the previous
is clocked out.

That is why I'm looking for a "start" pin on the chip, to be able to
say to all ADCs to start simultaneously.

> > If we are going to have multiple analog inputs at higt sample rate,

Do we understand each other correctly?

With a parallell bus I mean a bus with multiple data lines and multiple
address lines. Examples of parallell buses are ISA and PCI.

For the above chip you connect 16data lines cpu<->chip, the address
lines from the cpu must be connected to some decoding logic defining
the chips address.

To use this chip you activates sync, wait till all chip signalled drdy
and for each chip do two read cycles. The ad7762 has a 16bit wide data
bus, and one could potentially put one chip on the top half and another
on the lower half of the processors 32wide data bus. I don't know the
memory interface speed of the sam9260, but if it is 10MHz and you spend
two read cycles to get the data for two chips, the raw data rate would
be 10Mwords / s. If you divide that with 96kHz, you see that the bus
limit is 100channels (with a few ifs). Where the bus limit on spi
would be more along the lines of 8-16 channels.

> Also don't know how fast the

According to [4] you can run it up to 50MHz, but it depends on the
cpu and the chip you are communicating to, so 5-10MHz is more of what you
can expect.

...

Regards,
/Karl

[4] http://en.wikipedia.org/wiki/Serial_Peripheral_Interface_Bus

-----------------------------------------------------------------------
Karl Hammar Asp

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Messages in current thread:
Re: [LAU] open hw soundcard, Karl Hammar, (Sat Nov 14, 1:04 pm)
Re: [LAU] open hw soundcard, Joshua Boyd, (Wed Nov 25, 4:42 am)
Re: [LAU] open hw soundcard, Karl Hammar, (Wed Nov 25, 2:58 pm)
Re: [LAU] open hw soundcard, Paul Davis, (Sat Nov 14, 2:34 pm)
Re: [LAU] open hw soundcard, Folderol, (Sat Nov 14, 4:36 pm)
Re: [LAU] open hw soundcard, Karl Hammar, (Sat Nov 14, 10:42 pm)
Re: [LAU] open hw soundcard with ext. codec, Martin Homuth-Rosemann, (Tue Nov 17, 10:04 pm)
Re: [LAU] open hw soundcard with ext. codec, Karl Hammar, (Wed Nov 18, 5:37 pm)
Re: [LAU] open hw soundcard with ext. codec, Martin Homuth-Rosemann, (Thu Nov 19, 10:06 pm)
Re: [LAU] open hw soundcard with ext. codec, Karl Hammar, (Fri Nov 20, 12:56 am)
Re: [LAU] open hw soundcard with ext. codec, Folderol, (Thu Nov 19, 10:30 pm)
Re: [LAU] open hw soundcard with ext. codec, Karl Hammar, (Fri Nov 20, 1:01 am)
Re: [LAU] open hw soundcard with ext. codec, Folderol, (Fri Nov 20, 8:36 pm)
Re: [LAU] open hw soundcard with ext. codec, Karl Hammar, (Sat Nov 21, 11:26 am)
Re: [LAU] open hw soundcard with ext. codec, Folderol, (Sun Nov 22, 6:47 pm)
Re: [LAU] open hw soundcard with ext. codec, Karl Hammar, (Mon Nov 23, 1:40 pm)
Re: [LAU] open hw soundcard with ext. codec, Patrick Shirkey, (Sat Nov 21, 3:06 pm)
Re: [LAU] open hw soundcard with ext. codec, Karl Hammar, (Mon Nov 23, 1:45 pm)
Re: [LAU] open hw soundcard with ext. codec, Folderol, (Sun Nov 22, 6:52 pm)
Re: [LAU] open hw soundcard with ext. codec, Patrick Shirkey, (Sun Nov 22, 10:13 pm)
Re: [LAU] open hw soundcard with ext. codec, Karl Hammar, (Mon Nov 23, 3:08 pm)
Re: [LAU] open hw soundcard with ext. codec, Folderol, (Tue Nov 17, 10:20 pm)
Re: [LAU] open hw soundcard, Folderol, (Sun Nov 15, 5:50 pm)
Re: [LAU] open hw soundcard, Karl Hammar, (Sun Nov 15, 9:54 pm)
Re: [LAU] open hw soundcard, Folderol, (Sun Nov 15, 11:22 pm)
Re: [LAU] open hw soundcard, Karl Hammar, (Mon Nov 16, 12:32 pm)
Re: [LAU] open hw soundcard, Martin Peach, (Sun Nov 15, 10:52 pm)
Re: [LAU] open hw soundcard, Karl Hammar, (Mon Nov 16, 9:56 am)
Re: [LAU] open hw soundcard, Folderol, (Mon Nov 16, 9:14 pm)
Re: [LAU] open hw soundcard, Folderol, (Mon Nov 16, 10:26 pm)
Re: [LAU] open hw soundcard, , (Sat Nov 14, 10:20 pm)
Re: [LAU] open hw soundcard, Folderol, (Sat Nov 14, 10:31 pm)
Re: [LAU] open hw soundcard, , (Sat Nov 14, 10:54 pm)
Re: [LAU] open hw soundcard, Karl Hammar, (Sun Nov 15, 9:04 am)
Re: [LAU] open hw soundcard, , (Sun Nov 15, 11:17 am)
Re: [LAU] open hw soundcard, Karl Hammar, (Sun Nov 15, 11:38 am)
Re: [LAU] open hw soundcard, Paul Davis, (Sun Nov 15, 5:57 pm)
Re: [LAU] open hw soundcard, Karl Hammar, (Sun Nov 15, 7:06 pm)
Re: [LAU] open hw soundcard, Folderol, (Sun Nov 15, 6:54 pm)
Re: [LAU] open hw soundcard, Hans Wilmers, (Mon Nov 16, 1:25 pm)
Re: [LAU] open hw soundcard, Karl Hammar, (Sat Nov 14, 10:51 pm)