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Problem in impedance measurement from AD5933

Question asked by hitendra.sahu@iitb.ac.in on Mar 17, 2013
Latest reply on Mar 20, 2013 by musach

I am using AD5933 for resistance measurement at a single frequency. I have programmed the control registers and other frequency registers via I2C communication as follows, but i am not getting any output waveform at pin number 6 (Vout) of AD5933, and i am not able to observe any waveform on the Oscilloscope. Followings are the  hardware and software settings.

 

Hardware settings

5 V supply at pin no. 9.

3.3 V supply at pin number 10 and 11.

Measuring the output at pin no 6 (Vout) with respect to the ground (0V).

 

 

Software:

1. configured the Initialize freq resisters (0x82,83,84H) as 0x0F5C28 (30KHz).No of increment (0x00), Inc. Frequency (0x00).

all the values written successfully.

2. kept AD5933 in standby mode by writing to the control register (written successfully)

3. Issue reset command (D4=0) and set the internal clock (16.776 MHz) by writing 0x00 to the Lower control bits of the control register.(written successfully)

4 Issue Initialize with Start Frequency command by writing 0x10 to the higher bits of the control register.(written successfully)

  According to the datasheet it should set DDS output to the 2Vp-p(as D10=0 and D9=0) output at pin number 6, but when i am connecting oscilloscope then i am not getting anything.

Please let me know if i am doing anything wrong and if not then how can i observe DDS output on the oscilloscope.


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