Problem for CNA/CAN conversion

[A. Abellard]

Hello,
I would like to request some help for some students that work on an
Altera Stratix EP1S25 developpement board.
They try to deal with the Conversion Numeric/Analog , so they wrote
programs on VHDL where they declare a bit vector with a certain value,
and send it to the CNA to see the values on the output. But... no
matter the value they use, they always have zero volt on the outputs
However, I think they were very careful with the pins numbers
assignements of the components on the board.

And it seems they have the same kind of problem with the CAN
(receiving a simple voltage, and transfer it directly to the outputs
via the Stratix).

Can someone please help them (and me, by the way ?). I'm just
searching for some VHDL code to test the CNA and CAN conversions.

Many thanks,
Regards,
A. Abellard

 

[Nicolas Matringe]

Hi

A. Abellard a écrit:

Hello,
I would like to request some help for some students that work on an
Altera Stratix EP1S25 developpement board.
They try to deal with the Conversion Numeric/Analog , so they wrote
programs on VHDL where they declare a bit vector with a certain value,
and send it to the CNA to see the values on the output. But... no
matter the value they use, they always have zero volt on the outputs
However, I think they were very careful with the pins numbers
assignements of the components on the board.

They should make sure that the control signals are correctly generated.
It is sometimes not enought to juste put some digital values onto the
data bus of the DAC. This is where a logic analyzer comes in handy but
an oscilloscope can be enough.
Some DAC have a current output, not a voltage output. Make sure that the
output is loaded (1kohm should be ok)

And it seems they have the same kind of problem with the CAN
(receiving a simple voltage, and transfer it directly to the outputs
via the Stratix).

Are they sure they don't receive any digital value?

Can someone please help them (and me, by the way ?). I'm just
searching for some VHDL code to test the CNA and CAN conversions.

A simple counter generates nice sawtooth waveforms.

I once did a simple AM modulator to test such a design, I still might
have the VHDL somewhere. It was basically a sine look-up table, a
counter and a multiplier.
(and if you need further information, you can email me and even write in
french ;o)

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