ESP32-S3 board
The brain that runs your uploaded sketch.
01 First, know the pieces
What you need
Seven things, and every one of them has been aboard before. 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.
3 × rotary potentiometers
Three knobs — one for each colour channel.
RGB LED
Three lights — red, green, blue — in one dome with a shared pin.
3 × 220 Ω resistors
One in series with each colour leg to keep the current gentle.
Jumper wires
Temporary, solder-free connections — thirteen of them today.
Arduino IDE
Uploads the sketch to the board.
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. The pairing to keep in your head: the knob on GPIO 12 drives the red leg on GPIO 38, 13 drives green on 39, and 14 drives blue on 40.
Red knob middle pin
→GPIO 12
The board reads this knob to set how much red shows.
Green knob middle pin
→GPIO 13
The board reads this knob to set how much green shows.
Blue knob middle pin
→GPIO 14
The board reads this knob to set how much blue shows.
Each knob's outer legs
→3.3V and GND
The two ends give the middle pin a full sweep from zero to full voltage.
Red leg (via 220 Ω)
→GPIO 38
PWM on this pin sets the red brightness.
Green leg (via 220 Ω)
→GPIO 39
PWM on this pin sets the green brightness.
Blue leg (via 220 Ω)
→GPIO 40
PWM on this pin sets the blue brightness.
Common (long) pin
→3.3V
All three colours share this positive pin so a colour lights when its pin goes LOW.
The common pin goes to 3.3V. This is the same common-anode LED as Day 9 — the long common pin goes to 3.3V, the opposite of a single LED's ground leg. Each colour leg reaches its own GPIO through a 220 Ω resistor. 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 / 9 done
Seat the ESP32-S3 on the GPIO extension board and keep USB unplugged while you wire.
Place the three potentiometers on the breadboard with room to turn each knob.
Wire each knob's outer legs to 3.3V and GND so its middle pin can sweep the full range.
Run the middle pins to GPIO 12, 13, and 14 — red, green, and blue in that order.
Wire the RGB LED's red leg through a 220 Ω resistor to GPIO 38, green to GPIO 39, blue to GPIO 40.
Run the LED's long common pin to 3.3V.
Compare every wire to the chart before you plug in USB.
Open
Sketch_10.2_SoftColorfulLight.inoin Arduino IDE and upload it.Turn each knob in turn and watch its colour rise and fall in the dome.
04 Read just enough code
Read the code
Day 15 built one chain — read a knob, rescale it, write a brightness. Today the sketch runs that chain three times per pass using three small arrays and one loop. Switch to MicroPython if you'd rather see the same idea in Python — the wiring never changes.
const byte adcChns[] = {12, 13, 14}; // define the adc channels
const byte ledPins[] = {38, 39, 40}; // define led pins
const byte pwmChns[] = { 0, 1, 2}; // define the pwm channels
int colors[] = {0, 0, 0}; // red, green ,blue values of color.
void setup() {
for (int i = 0; i < 3; i++) { //setup the pwm channels
ledcAttachChannel(ledPins[i], 1000, 8, pwmChns[i]);//1KHz, 8bit(0-255).
}
}
void loop() {
for (int i = 0; i < 3; i++) {
colors[i] = map(analogRead(adcChns[i]), 0, 4096, 0, 255); //calculate color value.
ledcWrite(ledPins[i], 256 - colors[i]); //set color
}
delay(10);
}const byte adcChns[] = {12, 13, 14}Three matched arrays pair each knob with a colour leg — position 0 links the knob on 12 to the red leg on 38 and so on down the line. colors[i] = map(analogRead(adcChns[i]), 0, 4096, 0, 255)Reads one knob (0–4095) and rescales it onto the 0–255 brightness range in a single line. ledcWrite(ledPins[i], 256 - colors[i])Day 9's common-anode inversion — this dome lights when its pin goes LOW so the sketch subtracts the value before writing it. ledcAttachChannel(ledPins[i], 1000, 8, pwmChns[i])Gives each colour leg its own hardware PWM channel at 1 kHz with 8-bit brightness. Optional side path · same circuit
pwm0=PWM(Pin(40,Pin.OUT),10000)
pwm1=PWM(Pin(39,Pin.OUT),10000)
pwm2=PWM(Pin(38,Pin.OUT),10000)
adc0=ADC(Pin(12))
adc1=ADC(Pin(13))
adc2=ADC(Pin(14))
pwm0.duty(1023-remap(adc0.read(),0,4095,0,1023))
pwm1.duty(1023-remap(adc1.read(),0,4095,0,1023))
pwm2.duty(1023-remap(adc2.read(),0,4095,0,1023))pwm0.duty(1023-remap(adc0.read(),0,4095,0,1023))The whole chain in one line — read the knob, rescale to the 10-bit duty range, and subtract for the common-anode dome.Same wiring, one difference to expect: Freenove's Python version pairs the knobs to the colours in the reverse order — the knob on GPIO 12 drives the leg on GPIO 40 — and both pairings work fine. 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
Three chains, one loop
Day 15's single control chain — read the knob, rescale the number, write the brightness — appears here three times over, copied by a loop over three arrays.
Knobs in
analogRead measures each knob on GPIO 12 13 14 every pass.
map()
Each reading up to 4095 becomes a colour value from 0 to 255.
256 minus
The common-anode dome lights when its pin goes LOW so the sketch flips the scale before writing.
Every 10 ms
The loop refreshes all three channels fast enough that the colour rides your hands.
The model
colour = three knob readings → three mapped brightnesses
Why arrays and a loop
Writing the pins as three matched arrays lets one loop serve every channel. Adding a fourth channel would mean one more entry in each array and nothing else.
The same inversion as Day 9
The common pin sits at 3.3V, so a colour is brightest when its own pin is pulled LOW. Subtracting the value from 256 flips the scale so a bigger knob reading still means a brighter colour.
06 Know it worked
Test & debug
Nothing prints to the screen today — the proof is the colour under your fingers.
What you should see
- Turn one knob and one colour sweeps smoothly from dark to full while the other two hold steady.
- Set the knobs in combinations and the dome mixes the shades — red and green up makes yellow.
- All three knobs up glows white; all three down leaves the dome dark.
Every knob turned down means darkness by design — white takes all three channels at full.
If it doesn't
- One colour never changes? Check that knob's middle wire on GPIO 12, 13, or 14 — the board is reading air.
- Turning the red knob changes the wrong colour? The RGB legs are in the wrong order — red goes to GPIO 38, green to 39, blue to 40.
- The dome stays dark with knobs up? Check the common pin — it goes to 3.3V.
- Upload fails? Swap in a data-capable USB cable.
07 Make the idea yours
Try this: dial a sunset
Same working circuit, two experiments — one with your hands, one with a single line of code. It fits inside today's 25 minutes.
Dial a sunset
Turn the knobs until the dome glows sunset orange — red high, green partway, blue low. Write down roughly where each knob sits, as three numbers from 0 to 255.
Two-knob mixer
In the loop, make the blue channel reuse the green knob's value — set colors[2] = colors[1] after the map line — and the mix now lives on two knobs.
Logbook
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-DAY16-SOFTCOLOUR
Context packet
How the agent should behave: guide one physical connection at a time, wait for you to confirm, explain the knob-to-colour pairing on request, and always check wiring, board, port, and USB before changing code.