ADS8344 and AVR mega16

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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!


Re: ADS8344 and AVR mega16

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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.

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

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

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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.


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