I'm currently evaluating the AD9834 with the respective CN0304 EVAL Board. If I interface the DDS via SPI with my microcontroller, it does not generate output on IOUTB (the filtered output), only on IOUT. If I connect it to my SDP-CB1Z DSP Board with the respective GUI, it works on both pins.
That was the issue. Soldered a wire to L4 and applied 5V to it, now it works like a charm.
The current output of the IC are complementary outputs so if you probe at the pin outputs (since the eval board has load resistors) you should see an output on both. The only thing that I could imagine is that with your microcontroller you are programming a higher frequency than using the DSP board and that is being fitltered out on the filtered output. Again if ,as you say Iout has a waveform then the same should be visible is you probe on the IoutB pin itself.
languer said:the same should be visible is you probe on the IoutB pin itself
that's what I thought and it does work for the DSP board with the EVAL software, but not for my microcontroller. It puts out the correct waveforms in various frequencies but only on IOUT, not on IOUTB..
So same CN0304 EVAL, with your micro produces Iout at pin 19 of U1, but nothing on IoutB at pin 20 of U1. And same board produces both Iout and IoutB (same pins) using SDP-CB1Z DSP.
Never seen this, and it doesn't really make much sense. The only thing that I could see happening is the OPAMP (U4) is not getting voltage, but if you are supplying the +5V input with enough capacity that should not be an issue.
Ah, thats the issue I think. I attached 3v3 to both AVDD and DVDD and set the Jumpers as follows: LK1->A, LK2->A, LK3-> OUT, LK4->A.
But I don't see where I can attach 5V to it so that U5 generates 4.5V for U4. Do I really need to solder a wire to use the EVAL board completely without the SDP?