2-CH Precision Resistance Measurement System


This board can measure the absolute and relative resistance of most anything your can get your hands on over the order of nano to giga ohms be it the opposite ends of a bologna sandwich 500 feet away or a single resistor nested within a spiderweb of components.  The firmware is the heart of this unit and was developed with a host of provisions aimed at making measurements independent of environmental factors.  Of great consideration is that the device and its user interface were set up so that anybody can use the device with ease and confidence.  The device is designed to work at the industrial/extended industrial temp range and performs virtually independent of line length/temperature/peripheral circuitry.  This board would make an excellent pairing with the 4 Channel driver board for process control applications such as turning on a motor or sounding an alarm relative to a measured condition or defined set point.  The MCU used on this design is PIC18F46J50 or PIC24F32KA304.


  • Data-logging
  • Measurements are automatically formatted to show the most relevant data possible based off a formatting and centering algorithm.  This design currently displays what it measures using an 8-digit decimal value such as x.xxxxxxx or xxxxx.xxx
  • Direct interface with current loop, 802.11, 802.15 and daughter boards shown on this site
  • Measurements for each channel are time and date stamped using a menu configurable Real Time Clock
  • Each measurement channel can be independently turned off or on and each channel can be post processed to determine some desired value that is application specific.
  • Targeted Auto Ranging (Quantatinization of measurements, though inherently constant [i.e. 2^n], are dynamically ranged and centered in accordance with source resistance so measuring over a wide range of resistive values is of a much higher precision than using  a constant #Bit ADC over a fixed span of nano-giga ohms). In simple terms,  a 1 Ohm resistor is quantified roughly around a center point of 1 Ohm and likewise this center point is manipulated in accordance to other unknown resistances.  Though this approach is far more difficult to implement both in hardware and firmware, implementation of these features makes this system significantly more capable.
  • Firmware encryption
  • Ambient temperature of the board is constantly monitored (always available on the LCD glass)
  • User Help and How-To Menus
  • Company contact menus
  • Low power consumption = ideal for battery applications
  • Self Calibration
  • Over-voltage and isolation of various elements

Potential Applications

  • Resistance Measurement (captain obvious strikes again)
  • Temperature Measurement
  • Load Cell Measurement
  • Strain Gauge Measurement
  • PH/Corrosion Measurement
  • Pressure Measurement
  • Position/Angle Measurement
  • Humidity Measurement
  • Airflow Measurement
  • Galvanic Potential Measurement
  • Float/Level Sensor Measurement
  • Instrumentation Calibration
  • Process Control
  • All sorts of applications needing a precision reading derived from Ohms Law

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