From alsa-devel-owner@alsa.jcu.cz  Fri Sep 18 16:34:30 1998
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Date: Fri, 18 Sep 1998 16:33:42 +0200 (CETDST)
From: Ulf Axelsson <ulf@ore.ims.se>
To: alsa-devel@jcu.cz
Subject: Re: ESS1878 driver
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On Fri, 18 Sep 1998, Jaroslav Kysela wrote:

> On Fri, 18 Sep 1998, Ulf Axelsson wrote:
> 
> > Hi!
> > 
> > Some questions:
> > 
> > Perhaps there should be a common driver for ESS1868/69/78/79 that
> > handles the probably (looks like that in the docs) minor differences
> > between the cards?
> 
> Yes, that right.. Unfortunately I don't have free time to code driver for
> these chips now.. Do you write one?
>

Well, there is that thing about free time .... but i'm going to
try at least.

Although I was trying to avoid having several people all doing similar
drivers in a wasted effort. Anyone else working on drivers for one of
these cards/chips?
 
> > The card obviously can record and play 16bit 44Khz stereo sound. I
> > tested under WinNT and it appeared to work. CD^3 uses ESS1868 and they
> > claim they can do 16bit 44Khz stereo sound. Why does the docs say
> > that 16bit 22Khz stereo is the maximum programmable output rate?
> > (Or am I misreading the docs?)
> 
> Which docs? I have datasheet for ES1868 and here is rate range from 4kHz
> to 48kHz... The limitation is for full duplex - it can be only mono
> (not very good, but useable for network phone applications)..
> 

Yes, I did notice that full duplex can only be mono but I was referring
to other places in ds1878a.pdf.

Page 41: maximum 16 bit stereo transfer rate in compatibility mode is
11Khz.

(Hm: How things change when you read them a second time :-)

I obviously missed the more detailed specs on register A1h on page 56,
writing 11101110 to this register should give 44.19 kHz sample rate.
(bit 7 high!)
(16 bit stereo being setup separately in register B7h)

Quick calculation 44.19kHz * 2 channels * 2 bytes per channel is
172.8 kHz and thats far below ISA-bus speed. Right?

Next to figure out is how to use that extra 8bit DMA-channel.
I suppose their decision not to use any 16bit channels where intended
to minimize the amount of pins needed for the chip ?

But I'm getting ahead of myself, first I need to get PNP and detection
working (and PNP into the kernel at all).

(And I was supposed to work this weekend :-)

Mvh Ulf


