No ac output on AD5934

Sometimes, when the AD5933 code is reused, the internal oscillator gets selected as the source of MCLK. The AD5934 does not have the internal oscillator, and that causes the described symptom.

What is the DC voltage level at the VOUT pin while there is no AC? If it is zero, the chip might be stuck in Standby mode. Is the Enter Standby Mode command followed by Initialize with Start Frequency command (bit D12 is set to 1 in the control register 0x80)? After that the chip should be outputting AC voltage at the start frequency.

I'm not re-using any code - I'm using a Pi Pico and there doesn't seem to be a lot of Micropython code around for this - maybe because the standard i2c library in register access mode doesn't play nicely with the AD5934, so I've implemented the register access functions myself. I'll share it once I'm happy it's actually working!

On the real issues: - the hint to check the clock source is useful - the AD5934 data sheets says set to 0x81 D3 to 1 but doesn't say what it's for (thought I've now found it in the AD5933 datasheet), and I suspect that register is powering up in the wrong state - I have a vague memory of seeing it as 0x00 despite the data sheet saying it should be 0x08.

I have set the unit into "Initialize with start frequency" state after "Standby" ie. (load 0x10 into 0x80) and it hasn't made any difference. I think Vout stays at 0v.

I'll confirm both of those bits of info when I'm back in the lab on Monday.

Thanks for your help.

I should have said ''...especially when the AD5933 code is reused." 

Not really much of a help: with this remote guessing there is always a possibility of embarking on a wild-goose chase. Best of luck with your project!

I should have said ''...especially when the AD5933 code is reused." 

Not really much of a help: with this remote guessing there is always a possibility of embarking on a wild-goose chase. Best of luck with your project!