ADS8344 and AVR mega16

Hi,

I am about to create connection between an ADS8344 and a ATmega16, using
the SPI interface. Is there someone that can give me any tip?? Should I
have separate ground planes?? And if so, which of the pins on the
A/D-converter should be connected to the analog GND (AGND) and which
should be connected to just GND?? And the GND-pins on the mega16, they are
all digital, arn't they?? For the AVR mega16 I'll use a chrystal on about
6MHz. The A/D-converter have 8 analog signals of about 1V on the input and
the maintask for the AVR is just to convert the SPI-signal to UART-signal,
whick will be send further. Will the mega16 need any decoupling
capacitors?? In the datasheet of the ADC, there are some pictures of the
basic operation, including the decpupling capacitances and so on, but I
can't find anything about the mega16.

As you can see, I am new in the area and I am geatful for any information
I can get!

Ragrds
Frida

"Frida" <friost@foi.se> banged on the keyboard until producing
news:146564165266dc8718e5f55b61722c80@localhost.talkaboutelectronicequipm
ent.com: 

> Hi,
> 
> I am about to create connection between an ADS8344 and a ATmega16,
> using the SPI interface. Is there someone that can give me any tip??
> Should I have separate ground planes?? And if so, which of the pins on
> the A/D-converter should be connected to the analog GND (AGND) and

AGND should be its own plane, and should surround all the AGND pins and 
analog signals. There should be a SINGLE tie point between AGND and GND - 
single as if there were only a jumper connecting them. In fact, doing it 
that way and using a ferrite choke is not a bad way to go.

> which should be connected to just GND?? And the GND-pins on the
> mega16, they are all digital, arn't they?? For the AVR mega16 I'll use

Otherwise, GND is GND; it will be the digital ground used by all the 
other chips.

> a chrystal on about 6MHz. The A/D-converter have 8 analog signals of
> about 1V on the input and the maintask for the AVR is just to convert
> the SPI-signal to UART-signal, whick will be send further. Will the
> mega16 need any decoupling capacitors?? In the datasheet of the ADC,
> there are some pictures of the basic operation, including the
> decpupling capacitances and so on, but I can't find anything about the
> mega16. 

Decoupling caps are never a bad thing in ANY digital design :-)

> 
> As you can see, I am new in the area and I am geatful for any
> information I can get!

Decoupling caps should be _physically_ connected between your power 
supply and Vcc on the chips; branching the trace out to the cap is 
electrically "equivalent" but not functionally *identical*.

Google around to find tutorials on PWB/PCB layout & design; you'll find 
plenty of help.

HTH

-- 
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Dorsai - Author of Erotic Fiction
http://www.asstr.org/~Dorsai
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"Some mornings it just doesn't seem worth it to gnaw through the leather 
straps." -- Emo Philips