How to calibrate the ESC Current ADC?

New ESC firmware D460344 and above can calibrate the ESCs current sensing circuit. All ADC’s (Analogue-to-Digital Converters) introduce static errors to measurements. To calibrate the Current ADC on the ESC, find the ideal transfer function by following the steps below.

1) Begin by setting the Gain to 1 and the Offset to 0. Press the Send Settings button in the KDE Device Manager PC software. The current values in the ESC data log will now report the 12-bit ADC_value.

2) Run the ESC and motor from 1 to 10 amps by adjusting the throttle in 1 amp increments holding the throttle for a few seconds at each interval. The amperage can be measured using a DC power supply, Fluke DC current clamp, 200A RC Watt Meter, or multimeter.

3) After running the motor, disconnect the ESC and plug it into the KDE Device PC software and read the data log. This is done by clicking File -> UVC Series Data Log then clicking the "Read ESC Log" button.

e.g. Testing at 1-10 Amps, the ESC Drive Current (ADC_value) reported the following values:

4) Using the information from the data log, chart the data in excel. Open Excel then click Insert chart -> Scatter with Straight Lines and Markers. Then click on the chart -> Add Chart Elements -> Trendline -> More Options -> Trendline Options. Then click “Display Equation on chart” to see the equation.

5) Round the equation on the chart to the nearest tenth. The example shown would be: y = 19.5x + 18.1

6) Offset represents the y-intercept & Gain represents the slope. Go back to the Device Manager PC software and enter the values under Current ADC. Press the Send Settings button. The ESC current is now calibrated.