Convert an NTC ADC reading to temperature

Steps

Screens captured against Wokwi ESP32 Compiled with arduino-cli 1.5.2-rc.1 for esp32 core 3.3.11; booted headlessly with wokwi-cli 0.26.1 on 2026-09-07; serial line 'ADC=2048, R=10005 ohm, T=24.99 C' seen at 3.187 s (wall time from CLI start; scenario timeout 20 s simulated time); captured in the Wokwi web editor on 2026-09-09 on 2026-09-06; the tool may have moved on — the text steps are the contract.

1. 1 Step 1

   Do

   In the Simulation panel, inspect the NTC sensor wiring after pasting both supplied files.

   You will see

   The NTC sensor has power and ground connections, with OUT connected to ESP32 pin 32.

   Why it matters

   A calibration equation needs a named input before its result can be checked. Following OUT identifies the raw channel used by this setup.

2. 2 Step 2

   Do

   In the sketch.ino editor tab, find analogRead(32) and the raw-value range check.

   You will see

   The sketch reads 12-bit counts and rejects values at 0 or 4095 before calculating resistance.

   Why it matters

   The chapter distinguishes calculating a value from validating it. Range guards keep an invalid input from becoming a plausible corrected result.

3. 3 Step 3

   Do

   In the Simulation toolbar, click the play button and wait for compilation.

   You will see

   The timer starts and the Serial Monitor opens with ADC, resistance, and temperature results.

   Why it matters

   Fresh readings test the equation’s claim. Keeping raw and corrected values together makes the conversion open to review.

4. 4 Step 4

   Do

   In the Serial Monitor panel, read ADC, resistance, and temperature at the initial 25 °C setting.

   You will see

   The 25 °C setting produces 2048 counts, 10005 Ω, and 24.99 °C in the recorded run.

   Why it matters

   Residual error compares a corrected result with its reference. Here the model setting provides that comparison, rather than an independent temperature standard.

5. 5 Step 5

   Do

   In the sketch.ino editor tab, find the resistance calculation 10000.0*raw/(4095.0-raw).

   You will see

   The line uses a 10000 Ω reference value and the raw ADC count to reconstruct resistance.

   Why it matters

   The chapter keeps conversion coefficients with their input and output units. Here the intermediate resistance makes the path from counts to temperature visible.

6. 6 Step 6

   Do

   In the Simulation panel, select the NTC sensor and set its temperature control to 35 °C.

   You will see

   The 35 °C setting produces 1614 counts, 6505 Ω, and 35.00 °C in the recorded run.

   Why it matters

   A second input tests the conversion away from its starting point. The chapter warns that a straight calibration line can leave errors in a curved response.

7. 7 Step 7

   Do

   In the NTC control panel, restore temperature to 25 °C.

   You will see

   The Serial Monitor returns to 2048 counts, 10005 Ω, and 24.99 °C in the recorded run.

   Why it matters

   Repeating a known value checks whether the result returns. The chapter still calls for reference standards across the range and recorded recalibration conditions.