Substrate Calculator & Sensor Calibration
MT22 placement, water-content calibration and ESPHome configuration.
Configure substrate
INFWIN MT22 · SDI-12Measure the hydrated, settled medium. Dimensions also position the probe in the diagram.
Use actual dimensions from the product label. A nominal six-inch block is not necessarily a perfect cube.
Shot volume & runtime
Arithmetic from your chosen shot size and measured emitter flow.
Confirm delivery with a catch test. This is delivered water, not the resulting VWC increase.
Controller & YAML parameters
For a new configuration or an upgrade to the v3 calibration controls.
Use the pin actually wired to the data line. Generated YAML uses references to your local secrets file.
Position the sensor
SlabSchematic. Rod spacing is illustrative; use your real probe to transfer pin positions.
Midpoint is an initial comparison position. Check its readings against independent measurements before standardising it.
Print an actual-size placement template
Print at Actual size / 100%. Measure both check bars before using it.
Calibrate this setup
Manual readingsRecord the settled wet reference
Wet uniformly through the normal delivery path, then let free drainage settle. On a planted substrate, use a normal wet irrigation plateau.
A wet reference sets an index of 100. It does not establish 100% VWC or a calibrated dryback percentage.
Define the sample on the scale
Use a spare, unplanted sample of the same medium, packing and geometry. Keep its sensor position fixed between measurements.
Include the same container, sleeve, support and probe in every weighing. Air-dry medium can still contain water; use a defensible dry mass.
First moisture level
Not recordedSecond moisture level
Not recordedIndependent check
Not recordedWhy three points?
A and B establish an offset and gain around the probe's generic soilless response. They must differ by at least 100 RAW counts and 10 VWC percentage points. C must lie strictly inside the middle 80% of their RAW interval. Use the same physical sample; don't calculate C from the fitted curve.
The sensor receives VWC rounded to its 0.1% input step. The check below uses that same rounding.
Capture & check limits
Keep the defaults unless you have a documented reason. Increasing tolerance to make a failed check pass does not improve the calibration.
Your sensor setup
Setup only| Parameter | Set / verify |
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Apply on the sensor
- Fill in your own
secrets.yamllocally. Generate a new API encryption key in ESPHome. - Validate and build with ESPHome 2026.8.2, then install the generated device YAML.
- Open the device's web page. Press Apply wizard setup. This selects the medium and starts a fresh capture window.
- Complete calibration on the device using the calibration guide.
- Check saved values, turn Calibration mode off and wait at least ten seconds before disconnecting power.
This website creates files and instructions. It does not connect to your sensor or flash firmware.