I have the AD9850 and AD9851 version of this board.
I have written the necessary code to interface these with my microcontroller.
However, when I sample the sine output signal from the DDS it gets cut off like this:
I have connected the wires like this:
GND <-> uC GND
D7 <-> uC GPIO
WCLK <-> uC GPIO
FQUP <-> uC GPIO
REST <-> uC GPIO
Vcc <-> 3.3V (Tried 5V as well)
V-ADJ <-> uC GND, Not Connected and different values between 0V and 3.3V has been tried.
I have been trying with and without jumper J3 and J2. Trying to change the potmeter etc. But there is no change except for when I use a DAC and send a few hundred millivolts signal in on V-ADJ, then the signal gets attenuated and eventually zero. I have not been able to increase the signal amplitude or change its offset so the signal don't get chopped.
The sine signal is directly connected to the microcontroller ADC pin.
I am running out of ideas and are therefore asking for help/tips/experiences.
I should have had an oscilloscope for debugging this signal, but none available at the moment.
The schematic is:
Best Answer
Several things:
Could you test with a DIY oscilloscope? (such as the one that uses your audio card of the PC. (if the frequency range falls in the audio range)