Note this is an example "reference" to setup the ADuCM350 for 4-Wire Skin impedance measurements.
4-Wire measurements are for Absolute Accuracy and the ADuCM350 requires an external In-Amp.
For Relative measurements, the ADuCM350 can operate as a single chip solution.
Review AN-1302 for the differences between 2-Wire Skin Impedance and 4-Wire Skin Impedance. AN-1271 is useful to optimize the ADuCM350 Impedance engine for optimal performance.
- Documentation: AN-1302
- Eval-ADuCM350EBZ (LK1 is in place)
- ADuCM350 4Wire Bio Config 2 (Eval-ADuCM350BIOZ) board. (LK7, LK8, LK9, LK10, LK16, LK17, LK21 in place)
- ImpedanceMeasurement_4WireBioIsolated example in IAR Embedded Workbench
- View data in Comms port / Terminal IO (Check SDK Userguide in document folder for details).
SDK Download /Debug and Collect Data
- Download and Debug Code
- As Per SDK Quickstart UG-677
- In default mode 20KOhm+ 220pF || 100KOhm is selected.
- See 4-Wire Bio Config 2 schematic and layout.
- Theory / System connections documented in detail on AN-1302 apps note
- Once Code is Download -> Run Code and view data in Terminal I/O or UART.
- Should get results below out of box for default settings.
- Hardware Change: Remove LK17 and LK21. Insert LK19.
- Sensor now only the 20KOhm load.
- Repeat Measurement.
- Hit Reset and then Run buttons
- You should see 20KOhm in results display.
The raw DFT complex results (real and imaginary parts) and the final calibrated unknown impedances (represented in polar coordinates; magnitude and phase) are reported through the UART/STDIO. The USE_UART_FOR_DATA macro determines whether the results are returned to the UART or STDIO.
To return data using the UART, set the macro USE_UART_FOR_DATA = 1 (this is the default option).
To return data using STDIO, set the macro USE_UART_FOR_DATA = 0.