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AD9850 Frequency Generator


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I need to have a variable frequency generator in order to measure the inductance of a coil.

There are these very cheap AD9850 boards that can output sine waves of any frequency up to even 40Mhz.

Just what I need, so I took one of my old MSP430 battery charger boards and wired up the interface to the AD9850 board.

But it is not working, I get no output.  I've seen lots of Arduino's interfaced to them, but not any msp430.

 

I thought I figured out my problem when I discovered that at 5v power, a HIGH signal must be 4.9v,

and as I run my 430 at 3v, not going to work.  But the 9850 also runs at 3.3v, and then just 2.4v was high,

so I changed its power to 3.3v,  but no joy.

 

Was hoping someone else might have interfaced a 430 to one of these boards with success.

 

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Well, I finally got this working..sort of.  It looks to me the 9850 board has an issue with bad solder joints or something,

as it will output the signal but then stop and start again if I physically mess with it.  Thought it might be the 125mhz clock chip as pushing down it

got it outputing again, but that is not consistent, sometimes it doesn't work I need to twist the board and it works again,

and sometimes that doesn't work either, but eventually if I mess with it it outputs again until it stops again.

 

What may be of interest here is the code to compute the 32bit tuning word.  In general it is a floating point multiply, no good on a 430..

I broke it down into integer 16bit multiples.  If the code is of interest, I can post it,  it is on my other computer in the 'lab'. ;)

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