Thomas Fleckenstein wrote:
> PIC16C6x with 2MB serial flash memory as a data memory and a AD7714 ADC to
[snip]
> Now my problem is how to get the best out of the AD7714. It has a lot of
> features and I am really not sure how to set it up for optimum results.
> My questions:
> 1. I want to use 16bits for now ( later I will use 20bits ). How do I set
> the device for 16 bit operation ?
> 2. What is the SPI clockspeed i have to use ? The adc device uses a
> 2.4576MHz external crystal.
>    ( The PIC runs on 1Mhz )
> 3. I need some explanation on how to use the onchip calibration features as
> well as recommendations for the filter settings.
[snip]
> Thomas

As I already said here in the list, take to book and read one hour
before sleep everyday, after a couple of weeks you will understand
something about it.

1) Resolution you don't set, it gives you.  According with the filtering
settings, it will takes more or less time to do the ADC conversion.
Longer conversion, more accuracy, more bits.  There is a table at its
documentation about it.  To get around 16 bits, do conversions at max
speed of 60Hz. Take a look at table 1a and 1b at page 11.

2) SPI Clock as fast as you can, observe the max allowed at the manual.

3) Calibration can be done in several ways, internal and external, zero
and full scale, take a look at the calibration commands, some offset the
internal errors, others do the externals too. Pressure transducers
normally offer a small voltage without pressure, (the electronic bridge
is not perfect), the 7714 can offset it with the System Offset
Calibration.

--------------------------------------------------------
Wagner Lipnharski - UST Research Inc. - Orlando, Florida
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