/TeensyLCR

Primary LanguageC++MIT LicenseMIT

TeensyLCR

  • A Teensy 4.1 based LCR meter
  • measure capacitance, inductance, resistance and other complex parameters
  • 4 wire measurement
  • using an audio codec to measure voltage and current
  • ILI9341 320x240 Touchscreen with user interface

Features

LCR Meter

  • Basic accuracy of at least 1%
  • There are four ranges: 100R, 1k, 10k, 100k. The range will be selected automatically according to the impedance of the DUT.
  • Selectable test frequencies: 100 Hz to 90 kHz in 100 Hz steps.
  • Selectable test levels: 300 mV, 600 mV, 1 V

The following complex parameter of the DUT can be measured (fixed combinations of them):

  • Rs // equivalent series resistance (ESR)
  • Rp // parallel resistance
  • Cs // series capacitance
  • Cp // parallel capacitance
  • Ls // series inductance
  • Lp // parallel inductance
  • Phi // phase angle of impedance
  • Xs // series reactance
  • Z // impedance
  • Q // quality factor
  • D // dissipation factor
  • G // conductance
  • B // susceptance

Moving average of the readings can be set from 1 to 256.

Save screenshots to USB thump drive:

screenshot

Frequency Generator

  • A simple frequency generator for debug purpose
  • Signal output at HCUR connector
  • Waveforms: sinus only
  • Frequency: 1Hz - 90kHz
  • Amplitude: 1mVp - 2.4Vp
  • Offset: 0 - 1V
  • about 100R output impedance

Volt Meter

  • A simple voltmeter for debug purpose
  • use HPOT and LPOT inputs

Hardware

Board

  • Schematic
  • analog frontend using an auto balancing impedance bridge
  • 4 impedance ranges
  • PGA for voltage and current signals
  • Touchscreen, keypad and rotary encoder
  • temperature sensor near codec to measure board temperature
  • I2C eeprom to store calibration data and other settings

Software implementation details

  • Teensy Audio design:

Teensy Audio design

  • Phase calculation works exactly as described in TIDA-060029 LCR meter analog front end reference design.