ESP32-S3 board
The brain that runs your uploaded sketch.
01 First, know the pieces
What you need
Five things, one of them new. Tap Define on any part you haven't met — the answer opens as a field note you can read and dismiss without losing your place.
GPIO extension board
Spreads the pins into rows you can reach and label.
Rotary potentiometer
The knob — a resistor track with a sliding tap.
3 jumper wires (M/M)
Temporary, solder-free connections.
Arduino IDE
Uploads the sketch and opens Serial Monitor.
02 Make the physical circuit
Chart the circuit
The official Freenove diagram is your chart — schematic on top, the same circuit built on a breadboard below. Click it to enlarge. Three wires today, and each row below tells you where one goes and why.
Pot outer pin 1
→3.3V
Feeds one end of the knob's track with full voltage.
Pot outer pin 2
→GND
Holds the other end of the track at zero volts.
Pot middle pin 3
→GPIO 1
The wiper delivers the in-between voltage for the ADC to read.
Keep the pot on 3.3V. GPIO 1 is built to read voltages up to 3.3V, so power the potentiometer from the 3.3V pin — the 5V pin would push the wiper past that limit. Unplug USB before you move any wire.
03 One action at a time
Build it
This is the main path — you can finish the day without opening a single field note. Tap each step as you go to keep your place.
0 / 8 done
Seat the ESP32-S3 on the GPIO extension board and keep USB unplugged while you wire.
Push the potentiometer into the breadboard so each of its three pins has its own row.
Run a jumper from one outer pin to 3.3V and a second jumper from the other outer pin to GND.
Run the third jumper from the middle pin (pin 3) to GPIO 1.
Compare every wire to the chart before you plug in USB.
Open
Sketch_08.1_ADC.inoin Arduino IDE and upload it.Open Serial Monitor and set the baud rate to
115200.Turn the knob slowly from one end to the other and watch the numbers sweep.
04 Read just enough code
Read the code
The working part of the sketch is four lines, five times a second — read the pin, do one line of arithmetic, print, wait. Switch to MicroPython if you'd rather see the same idea in Python — the wiring never changes.
#define PIN_ANALOG_IN 1
void setup() {
Serial.begin(115200);
}
void loop() {
int adcVal = analogRead(PIN_ANALOG_IN);
double voltage = adcVal / 4095.0 * 3.3;
Serial.printf("ADC Val: %d, \t Voltage: %.2fV\r\n", adcVal, voltage);
delay(200);
}analogRead(PIN_ANALOG_IN)Measures the voltage on GPIO 1 and returns which of the 4096 steps it lands on, as a number from 0 to 4095. adcVal / 4095.0 * 3.3Converts the reading back into volts — 4095.0 is the top reading, so a full turn lands exactly on 3.30V.Serial.printf("ADC Val: %d, \t Voltage: %.2fV\r\n", adcVal, voltage)Prints the raw reading and the voltage on one line, five times a second. Optional side path · same circuit
adc=ADC(Pin(1))
adc.atten(ADC.ATTN_11DB)
adc.width(ADC.WIDTH_12BIT)
adcVal=adc.read()
voltage = adcVal / 4095.0 * 3.3
print("ADC Val:",adcVal,"\tVoltage:",voltage,"V")adc.atten(ADC.ATTN_11DB)Opens the input range so the pin can read the full 0 to 3.3V sweep.adc.width(ADC.WIDTH_12BIT)Sets 12-bit readings — 0 to 4095 — the same scale the Arduino core uses by default.Same pins, same wiring. MicroPython asks you to set the range and the resolution yourself — the two adc. lines above — where the Arduino core picks those defaults for you. Run it in Thonny if MicroPython is set up; otherwise skip it — it should never block the Arduino-first path.
05 Understand, don't memorise
Voltage in, number out
Every day until now, a pin gave your code one bit — high or low, on or off. A knob doesn't work in bits; it sits anywhere across a range. Today's chip has a piece of hardware, the ADC, built to measure that range and translate it into a number. Understanding how it slices the range is the whole lesson.
Pins spoke in two states
Every pin you've used reports one of two things — near 3.3V for HIGH or near 0V for LOW, a single bit. A turning knob rests anywhere across that span, so reading it needs a pin that can measure the whole voltage, not just pick a side.
Position becomes voltage
The potentiometer wires across 3.3V and ground as a voltage divider you turn by hand. Its middle pin — the wiper — taps off a voltage that slides smoothly from 0 up to 3.3V as you rotate the shaft.
Voltage becomes a number
The ADC — analogue-to-digital converter — divides the 0 to 3.3V range into 4096 evenly spaced steps and reports which step the wiper's voltage lands on. That step count is the ADC's resolution — twelve bits, and 2 to the 12th is 4096 levels.
analogRead hands it over
analogRead returns that step as a whole number from 0 to 4095, five times a second. One line of arithmetic scales it back into volts, so you see both the raw step and the voltage it stands for.
The conversion
voltage = reading ÷ 4095 × 3.3
Why the top step is 4095
Twelve bits number the steps 0 through 4095, so the count stops one short of 4096 — 4095 is the top step and stands for the full 3.3V, which is why the code divides by 4095.0. Each single step covers about 0.8 mV, since 3.3V is spread across 4096 levels.
The knob is a divider you turn
The resistive track splits 3.3V along its length, and the wiper taps off the share at its position. Turning the shaft moves that tap, so the middle-pin voltage — and the number the ADC reports — follows your hand.
Why the last digit wobbles
The finest steps are tiny — under a millivolt each — and any real circuit carries a little electrical noise, so a held reading drifts by a count or two. Judge a knob position by the whole sweep rather than the last digit.
06 Know it worked
Test & debug
Success and recovery sit side by side, so you never have to go hunting when something looks off.
What you should see
ADC Val: 0, Voltage: 0.00VADC Val: 2048, Voltage: 1.65VADC Val: 4095, Voltage: 3.30V
The values track the knob — one end reads near 0, the other near 4095, and every position between prints its own pair.
If it doesn't
- Stuck at 0 or 4095? Check the middle-pin wire on GPIO 1, then the two outer pins on 3.3V and GND.
- Garbled or random characters? Set Serial Monitor to 115200 baud to match the sketch.
- Blank monitor? Confirm the right board and port, then swap in a data-capable USB cable.
- Reading jitters by a few counts? That's normal for a real ADC — judge by the whole sweep.
07 Make the idea yours
Try this: chart your knob
Same working circuit, one new habit: reading the world through numbers. It fits inside today's 20 minutes.
Find the midpoint
Turn the knob until the reading sits near 2048 — half of 4095. Now look at the shaft. Is it pointing roughly halfway round its travel? You just found a physical position using nothing but a number.
Map the sweep
Pick three spots — a quarter turn, halfway, three-quarters — and write down both the reading and the printed voltage at each. Then check the pattern. Does halfway on the dial land near halfway up the scale, close to 2048 and 1.65V? Hold one spot still and watch how few counts the number drifts.
08 Learn it with a hand on the tiller
Coach me through it
Every lesson ships with a code and a machine-readable packet, so an agent can guide you with full context.
Lesson code
TSK-DAY13-ADC
Context packet
How the agent should behave: guide one wire at a time, wait for you to confirm, and explain the analogue idea on request — that this pin measures a whole voltage range and reports it as a number from 0 to 4095. Always check wiring, board, port, and baud rate before changing code.
Keep your place
Finished Day 13?
Mark it complete — it shows on your course map, and your place is saved on this device.