2012-09-04 07:38 PM
Hi All,
I had the DAC working using DMA to out put a sinewave continuously and it seems to have stopped working when I tried to change which timer I triggered off. After changing the timer configuration back it still doesn't work. I believe I configure everything I need to and I have code that read DAC->DOR1 out via the USART and it shows this data updating as I expect but I don't see any voltage on the DAC pin. Any ideas? Regards, Daniel #dac2013-01-29 11:45 AM
I remember a similiar thread, who got probably lost in this forum ...
I'm pretty sure you enabled the output buffer for the DAC. Take a closer look at the datasheet. With this output buffer enabled, you have an offset voltage of up to 200mV at zero output. Not exactly rail-to-rail, but not so bad compared to other opamps.2013-01-30 10:49 AM
output buffer is desabled (:
if enable then voltage is 200 mVit's bad.2013-01-31 01:27 AM
How do you load the DAC ?
To cite from the datasheet (5.3.18, tbl 46):When the buffer is OFF, the Minimum resistive load between DAC_OUT and VSS to have a 1% accuracy is 1.5 MOhm.
I guess you need a buffer stage, or need to increase the input impedance of the existing one.