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Problem for CNA/CAN conversion

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

Reply to
A. Abellard
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Hi

A. Abellard a écrit:

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)

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

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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Reply to
Nicolas Matringe

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