Nianyu Jiang

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  1. https://www.researchgate.net/publication/236037769_A_four-electrode_low_frequency_impedance_spectroscopy_measurement_system_using_the_AD5933_measurement_chipt this is the paper I am talking about. Thanks for the further explaination, I start understanding the working principle and trying to combine everything. Will go back to you once I have more question. Nianyu Jiang
  2. Hello Colvin, Thanks for the answer. I understand your answer for 1 & 2. For the 3 & 4, since we need the ADC input signal stay in the range of 0 - Vdd, we need to use the mux (part 3) to select the resistor to choose the gain (5 or 1), is that right? I will read more on datasheet and the post you forward to me to understand the equation. Thanks a lot! Nianyu Jiang
  3. Hello guys, I am trying to extend PmodIA from 2 electrodes to 4 electrodes (for better accuracy). I got some paper talking about how to do that directly from AD5933 chip, but I see there is already some electrical components integrated on the PmodIA board, so I am trying to figure out the circuit. The attachment is PmodIA scheme and I highlight the part which I am trying to understand. 1. I believe this is high pass filter to move the offset. 2. I believe this is Op-Amp, but why do we need this? 3. I think this is a switch or multiplexer, but why do we need this here? 4. Same as part 2. I would be really appreciate if someone can give me a brief answer or forward me some related material. Thanks a lot! Nianyu Jiang
  4. Hi guys, Just fixed the problem. In the library (.cpp), the register address of calling external clock is wrong (0x08). By changing it to 0x80, the code works good right now. I tested 500 and 100Hz, which works perfectly fine. Thanks again to Colvin and Jon for your time and help. Nianyu Jiang
  5. Hello Jon, The system cannot work by simply changing "false" to "true", I think it might be the problem of the library. I will try to contact with the author of library and ask his opinion. Thanks. Nianyu Jiang
  6. Hi Colvin, Thanks for the response. Yes, the datasheet doesn't say anything about the limitation of the oscillator frequency, but I was reading a lot of paper works which connected lower frequency clock to the chip. I will try the method suggested by Peyron and posted here.
  7. Hello! I am trying to add external clock (32KHz) to the PmodIA for low frequency generation, however, I have no idea how to change the Arduino code, could anyone tell me how to modify my arduino code or even library to make things work? The code works good calling internal clock, the information is attached below. Thanks for the help! External Clock information: https://www.digikey.com/product-detail/en/abracon-llc/ASFLK-32.768KHZ-LJ-T/535-9546-6-ND/1882844