I made a PCB on which I connected the AD9959 DDS (not evaluation board) with a µController. In order to program the DDS via SDIO in SPI mode I perform the follwing steps:
-Select all Channels with: 0x00, 0xF2
-Write FTW to all Channels: 0x04, 0x02, 0x8F, 0x5C, 0x29
And here is my problem:
It works great with Channel 2 and 3, but I can't get any signals from the CH0 and CH1. CH0 and CH1 show always a DC current. They are connected in the exactly same way with AVDD as CH2 and CH3 are.
I also tried to programm the channels individually. For CH2 and CH3 it works perfectly. For CH1 and CH0, I don't get any signals.
Do CH0 and CH1 additional ciruitry or are the the same as CH2 and CH3? What could be wrong?