ESP32-S3 board
The brain that runs your uploaded sketch.
01 First, know the pieces
What you need
Six things, most of them small. 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.
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.
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. Each connection tells you where the wire goes and why.
Red leg (via 220 Ω)
→GPIO 38
One PWM channel sets how much red shows.
Green leg (via 220 Ω)
→GPIO 39
One PWM channel sets how much green shows.
Blue leg (via 220 Ω)
→GPIO 40
One PWM channel sets how much blue shows.
Common (long) pin
→3.3V
All three share this positive pin so a colour lights when its pin goes LOW.
The common pin goes to 3.3V. This is a common-anode LED, so the long common pin goes to 3.3V and not to ground — the opposite of a single LED. 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.
Find the RGB LED's long pin — that's the common one shared by all three colours.
Wire the red leg through a 220 Ω resistor to GPIO 38.
Wire the green leg through a 220 Ω resistor to GPIO 39.
Wire the blue leg through a 220 Ω resistor to GPIO 40.
Run the long common pin to 3.3V, not to ground.
Compare every wire to the chart before you plug in USB.
Open
Sketch_05.1_RandomColorLight.inoin Arduino IDE and upload it.Watch the dome change colour again and again.
04 Read just enough code
Read the code
The sketch sets up three PWM channels, then paints a colour by giving each one a brightness. Switch to MicroPython if you'd rather see the same idea in Python — the wiring never changes.
const byte ledPins[] = {38, 39, 40}; // R, G, B
const byte chns[] = {0, 1, 2};
void setup() {
for (int i = 0; i < 3; i++) {
ledcAttachChannel(ledPins[i], 1000, 8, chns[i]);
}
}
void loop() {
int red = random(0, 256);
int green = random(0, 256);
int blue = random(0, 256);
ledcWrite(ledPins[0], 255 - red); // common anode: LOW = brighter
ledcWrite(ledPins[1], 255 - green);
ledcWrite(ledPins[2], 255 - blue);
delay(200);
}const byte ledPins[] = {38, 39, 40}The three pins are the red, green, and blue legs in that order. ledcWrite(ledPins[0], 255 - red)Writes 255 minus the value because this common-anode LED lights when its pin goes LOW. red = random(0, 256)Each colour gets a fresh brightness from 0 to 255, and setting all three at once mixes the shade. Optional side path · same circuit
pins = [38, 39, 40] # R, G, B
pwm0 = PWM(Pin(pins[0]), freq=1000)
r = random.randint(0, 1023)
pwm0.duty(1023 - r) # common anode: invert with 1023 - valuepwm0.duty(1023 - r)MicroPython's duty here is 10-bit, so it inverts with 1023 minus the value instead of 255.Same pins, same wiring. 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
One colour from three primaries
There's no trick here — three small lights sit close together and PWM sets how bright each one glows.
One dome
Red green and blue sit side by side under one lens.
PWM each
A PWM channel dials each colour from off to full.
Your eye
The three glows overlap and read as one colour.
White
Red green and blue at full together look white.
The model
colour = red + green + blue at chosen brightnesses
Why the code inverts each value
The common pin sits at 3.3V, so a colour is brightest when its own pin is pulled LOW. Writing 255 minus the brightness flips the scale so bigger still means brighter.
Three lights in one part
An RGB LED is three coloured LEDs packaged together, each with its own leg and a shared common pin.
06 Know it worked
Test & debug
Nothing prints to the screen today — the proof is the colour in the dome.
What you should see
- The RGB LED glows a colour.
- Every fraction of a second it jumps to a new random colour.
- It keeps changing for as long as the board has power.
The colours look random on purpose — each one is a fresh mix of red, green, and blue.
If it doesn't
- Only one colour ever appears? Check that colour's 220 Ω resistor and its GPIO wire — the other two legs may not be reaching their pins.
- Nothing lights at all? Check the common pin — it goes to 3.3V, not to ground.
- A colour is stuck full-on? Suspect the common-anode wiring or the wrong leg on that pin.
- Upload fails? Swap in a data-capable USB cable.
07 Make the idea yours
Try this: choose a status colour
Same working circuit, one design choice: picking a colour that carries meaning. It fits inside today's 25 minutes.
Name a colour
Decide on a colour that would read as ready or as a warning, then write down the red, green, and blue numbers from 0 to 255 that would make it.
Let it drift
Upload the gradient variant Sketch_05.2_GradientColorLight.ino and watch the colour slide smoothly instead of jumping.
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-DAY09-RGB
Context packet
How the agent should behave: guide one physical connection at a time, wait for you to confirm, explain the common-anode inversion on request, and always check the common pin, wiring, board, and USB before changing code.