Re: digital to analog conversion conventions

On Tue, Apr 01, 2003 at 08:00:15PM +0200, Alberto LUSIANI wrote:
> For the boards I am using (and in general, for what I can see) Comedi
> seems to assume that the largest DAC input (4095 or 65535 typically)
> does match exactly the upper range (10V typically).

Comedi just follows the definition stated in the user manual
for the board.  Almost every manufacturer makes the maximum
point correspond a voltage that is a round number.  Most boards
can be calibrated to some other definition, but that seems
unwise unless specifically necessary.

An important point to keep in mind is that because of the
nature of DAC technology, there is _often_ some point in the
DAC transfer function that is up to 1 LSB different from the
linear fit to the transfer function.

dave...