(d) I am using 3.3 VDC and my output excitation range is 1 which means output excitation voltage is 1.98 Vp-p with DC offset 1.48 V. (c) Schematic picture of my circuit is below. The 2nd bit of the status register does not go high, which means the AD5933 is not getting valid real and imaginary values. In the code, you can see the while loop, which is waiting for valid real and imaginary value by reading the flag set (2nd bit) in the status register of the AD5933. (b) I used a function generator to apply an external clock frequency shown in the attached picture, but the AD5933 is not responding. Now, I decided to measure impedance below the 5 kHz frequency range and according to the UG-364 application note, we have to use an external oscillator to apply a clock frequency of 250 kHz to use the frequency range below 5 kHz. I have measured different resistor and capacitor combinations using the internal oscillator. (a) I have used the internal oscillator and I can measure impedance from 5 kHz to 100 kHz frequency range. The communication (I2C) between controller and AD5933 is good. I am using a function generator to give 250 kHz, 2-volts peak square wave signal to MCLK pin, but it's not working. There is an option to connect an external clock. I am using AD5933 impedance measurement chip.
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