Um, I know this is a DSP forum but I can't find any similar discussion
groups for analog devices, and there seems to be a wide range of useful
subjects discussed on these boards so I am hoping someone can give me some
I am having a problem with an ADC evaluation board I purchased recently
(AD7266). The board comes with an optional Eval-Board-Controller, which
can be used (via a 96-way connector) to provide the necessary SCLK, Chip
Select, power etc. signals and to read the ADC digital data. The same
signals can be provided externally, and the appropriate links on the board
must be set to the correct position to indicate what the source of these
signals is (Eval-Board-Controller or externally supplied by the user).
Now, I couldn't afford to purchase the controller, but I was hoping that I
could still configure the board to use the 96-way connector to read the
SCLK and CS signals from FPGA header pins, and likewise write the ADC data
to the FPGA using the pins that on the 96-way connector pin-out are
designated as the Serial-Data-In pins for the Eval-Board-Controller. I
need to do this since the header on the FPGA board I am using is the only
I/O on the board.
My problem is as follows:
The technical note implies that the Eval-Board-Controller supplies four
clock sources labelled SCLK0 (on two pins) and SCLK1 (on two pins). In the
schematic diagram these pins are all tied together at a common junction
before being fed to the SCLK pin of the ADC. I don't know if the '1' and
'0' refers to the polarity of the clock signal. I wondered if I would need
to have four similarly configured sources, but I decided to just use one
clock source to drive the SCLK pin.
When I do this, I see the clock signal (centred about ground) on what
should be the data output pins, and on the analog input pins.
I am hoping this doesn't mean I have damaged the board, but does anyone
have any suggestions about how I can safely use the 96-way connector as an
interface with the FPGA, and avoid the problems described above?
Reply by Jerry Avins●July 27, 20062006-07-27
> I am hoping this doesn't mean I have damaged the board, but does anyone
> have any suggestions about how I can safely use the 96-way connector as an
> interface with the FPGA, and avoid the problems described above?
Have you tried talking to AD technical people on the phone? I've found
them very helpful in the past.
Engineering is the art of making what you want from things you can get.