Analyzing Circuits Using the Espotek Labrador: Software Bug

2 minute read

How to resolve a possible software bug on the Labrador.

Update August 1, 2021

I’ve noticed that the “Paused” check box appears to “delete the buffer and force a reload”. For example, I might see some clipping on a sine wave and if I check/uncheck Paused, the wave will appear accurately. This would help explain why “checking and unchecking Paused” can fix a multitude of sins. Therefore my new advice is, if your results aren’t what you expect, do the following:

  1. Ensure your power supply setting is high enough (+1.6V above expected signal) to cover the expected results. This is very important when measuring an AC signal such as a sine wave.
  2. Make sure you are able to see the signal:
    • If you don’t see a signal at all, press M or Oscilloscope -> Show Range Dialog on Main Page and adjust Vmax such that you can see a signal.
    • Ensure your screen is showing a good signal and the signal is not a flat signal with no noise.
    • Checking (Clicking) and unchecking Paused on Oscilloscope CH1 can frequently change a flat signal to a good signal.
      Flat Signal vs. Good Signal

      Flat Signal vs. Good Signal

  3. Make sure Trigger is unchecked if you are measuring a AC signal such as a sine wave.

If you continue to have problems with the Multimeter, remember:

  1. Oscilloscope CH1 and CH2 are the probes for the DMM.
  2. Voltage measurements are a differential measurement, which means you are measuring the difference between CH1 and CH2.
  3. Ensure both CH1 and CH2 signals show on the screen then use the vertical cursors to measure the difference between the two signals.

I have found that this method can be extremely accurate.

Detailed Description

There appears to be a bug in the software for the Multimeter function. When attempting to measure voltage using the Labrador Multimeter, you might see this issue:

  • Multimeter will show approximately 3V for any voltage above 3V
  • Or if measuring a voltage that goes negative, the range will be limited to +3V and -3V

If You Prefer the Solution in Video Form

Illustration and Solution to Bug in Long Form

Confirm Bug Exists: Hardware

Setup

  1. Plug Oscilloscope CH1 (Orange wire) into measure the positive socket on the Labrador
  2. Use Oscilloscope CH2 (Blue wire) into the ground socket on the Labrador
  3. Plugin Labrador to USB on computer and start the Labrador application
    Labrador performing a closed loop test

    Labrador performing a closed loop test

    Pinout of Labrador

    Espotek Labrador Pinout

Confirm Bug Exists: Application

In the Labrador Application

  1. Start the Labrador application
  2. Immediately Uncheck Oscilloscope CH1 box
  3. Check Multimeter box

If the bug exists, the Multimeter will show approximately 3.01V and it needs to show approximately 4.5V (Note all 4 values Max/Min/Mean/RMS are exactly the same)

Labrador showing MM bug

Labrador showing MM bug

Three Step Fix In the Labrador Application

  1. Uncheck Multimeter and check both Oscilloscope channels then press M to bring up Range Dialog and enter 5V for Vmax (remaining values don’t matter)
    Increase Vmax to 5V

    Increase Vmax to 5V

  2. Check and Uncheck Paused under Oscilloscope CH1
    Check and uncheck Oscilloscope CH1 Pause

    Check and uncheck Oscilloscope CH1 Pause

  3. Uncheck Oscilloscope CH1 and CH2 and check Multimeter and the values will be accurate
    Correct values shown

    Correct values shown

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