Prof Bogatin''s Software Defined Instrument Research Program

Research program on Software-Defined Instruments (SDI)

An SDI is a hardware platform capable of data acquisition that is turned into a specialized instrument for a custom application using software. This includes the software running on the hardware and the external control software.

In our program, we have two different types of hardware platforms:

  • Microcontroller based
  • Commercial off-the-shelf (COTS) general-purpose instruments

The focus of our initiative is developing low-cost and high-performance SDIs for specific killer apps, encouraging undergraduate and graduate students to participate. We have five specific programs we are pursuing:

  1. Using the Arduino Atmega 328 uC with direct data streaming into Excel, leveraging its sweet spots:
  • Timing resolution of 62 nsec (1 clock cycle)Ìý for time interval or frequency measurements
  • ADC vertical resolution of less than 100 uV using averaging over 20 msec intervals and acquisition rates of 45 kSps.
  • Analog voltages with 20 mV resolution and a transient response time of no shorter than 100 msec, which can be buffered to higher voltage and current

Even so, this hardware platform enables the following very low-cost and high-performance SDIs

  • High precision frequency meter with sub 1 ppm precision in a 20 msec averaging interval
  • A capacitance meter sensitive to 1 ppm precision in a 20 msec averaging interval
  • A multi-channel strip chart recorder
  • A multi-channel current load analyzer for battery discharge or component accelerated aging evaluation
  • Static electric field detector
  • Simple heartbeat sensor
  • Smart sensor interface

When an application requires higher performance, it's time to advance to another uC with a Python interface.Ìý

  1. Using a SAMD21 uC in a QT-PY form factor to create a smart solderless breadboard with the following specs:
  • ADC with 12-bit vertical resolution and 170 kSamples/secÌý
  • A True DAC, 10-bit vertical resolution and 100 kSamples/sec, with buffered output for higher voltage and current

There are fundamental limits to the noise in an ADC and DAC integrated into the chip since they live in the very noisy digital environment of the chip. For lower noise, external ADCs and DACs are used such as the

  • MCP3202 12-bit, 100 kSps ADC
  • ADS1115 16-bit, 400 Sps ADC
  • MCP4725 4 channel 12-bit DAC with buffer
  • DDS function generator

This platform is capable of creating a wide variety of low-cost, high-performance instruments. The current ongoing projects with this platform include some of those above and;

  • A uVmeter to measure reference voltage source drift and temperature sensitivity
  • A uohmmeter to measure solder joints and vias
  • A high current, high voltage buffered function generator
  • A STEM_Lab complete set of desktop instruments for use in hands-on electronics labsÌý to mimic the Diligent AD3 for $8
  • A step response analyzer
  • A VRM Thevenin resistance analyzer
  • A square wave-based Bode and impedance analyzer
  • A sine wave-based Bode and impedance analyzer
  • A high-performance, high-current, high-voltage isothermal curve tracer to study non-linear component behavior
  • An electrical impedance tomography imaging systemÌý
  • A noise spectrometer to measure excess 1/f noise in resistors and opAmps
3. The ESP32 C6 with wireless communication for smart sensor IoT nodes. The current projects involve sensor nodes for
  • Earth sensing, including ionizing radiation, rf background, magnetosphere, and Earth tides
  • Environment sensing
  • Weather sensing including lightning, electric fields and ions in the air
  • Air quality/gas sensors
  • Water quality sensors
  • Biometric sensors such as EEG, EKG, EMG, surface resistance, O2 and NFIR metabolic rates
  1. A customized instrument shield for use with any R3 uno form factor uC platform which includes
  • ADC 16-bit 400 SpsÌý
  • DAC with 12 bit, 100 kSps an buffered output
  • Eload
  • Connections for plug and play I2C smart sensor modules
  • Capacitance meter with a 555 timer interface
  • DDS function generator
  1. Using commercial off-the-shelf (COTS) instruments to create custom instruments.Ìý

This is made possible using general instrument hardware platforms, which are designed to interface to a computer using either the USB, Ethernet, or IEEE488 bus for remote instrument automation. Usually, the interface protocol is either SCPI-based or there is an SDK for the instrument. This initiative focuses on developing labs for a new course for release in Spring 2027, ECEN 4000/5016: Instrument Automation and Measurement Analysis.

These SDIs span two classes of instruments: high-end benchtop instruments such asÌý

  • scopes
  • function generatorsÌý
  • smart power supplies
  • dedicated VNA
  • frequency counter
  • impedance analyzers

and very low cost, multifunction COTS instruments such as

  • the Digilent AD3 ($379)
  • the PicoTech P2204 scope ($185)
  • Hantek scope H6022BE ($65)
  • ADALM1k ($95)
  • ADALM2k ($190)
  • LabJack U3 ($160)
  • Red Pitya -125 ($500)
  • PC sound card adaptor and PCB interface ($50)

Research projects for students in this initiative involved developing and characterizing the SDI and then applying the instrument to a specific killer app. These projects will be published in journals such as

  • IEEE Trans. on Instrumentation and Measurements
  • Nuts and Volts
  • Physic Teacher
  • All about circuits

If you are interested in working on these projects, contact Prof Eric BogatinÌý