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AD9958: No output

Question asked by stgtroman on Aug 30, 2012
Latest reply on Jan 31, 2013 by Matthias_H

Hello

 

I have developed a board using the AD9958 and it's not working properly. The DDS is controlled by a ATmega on a Arduino board.

I have attached the schematics.

The communication via SPI works, but there is no output on both channels. First I want to run the DDS in single tone mode.

 

For initialising I send over SPI following.

CSR set to 0xC2

FR1 set to 0xD050A0 (>255MHz, PLLx20, CP 75µA, Single Tone Mode.)

CFTW0 set to 0x0083126E (1 MHz)

IO_Update

 

After that I read all registers. CSR and FR1 are correct but CFTW0 is 0x00000000. If I select only one channel CFTW0 is read correctly. But there is no frequency on the outputs on both constellations.

 

I tested Sync_CLK (FR1 0xd05080) and there is an output with 125MHz.

 

I'll appreciate any hint for the troubleshooting of the problem.

 

Thanks,

Roman Ritter

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