Day 22 · Motor driver: control motion safely

01 First, know the pieces

What you need

Six pictured parts plus one you supply yourself — a 9V battery. Freenove leaves the battery out of the box, so have a fresh one ready along with the kit's battery line (the clip-on lead that reaches the extension board). 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.

Official manual photo of the ESP32-S3 development board. — Manual photo

ESP32-S3 board

The brain that runs your uploaded sketch.

GPIO extension board

Spreads the pins into rows — and carries the battery's power today.

DC motor

The part that moves — current through its two terminals spins the shaft.

Official manual photo of the L293D motor driver chip, a sixteen-pin integrated circuit. — Manual photo

L293D driver chip

Takes the board's small signals and switches the battery's current.

Rotary potentiometer

The knob — one sweep sets both speed and direction.

Official manual image of a jumper wire. — Manual photo

Jumper wires (M/M)

Temporary, solder-free connections.

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. More wires than usual today, so take the connections one row at a time.

Official Freenove circuit for driving a DC motor with an L293D: the chip's In1, In2, and Enable1 pins wired to GPIO 13, 14, and 12, a rotary potentiometer feeding GPIO 1, the motor on the chip's Out1 and Out2, and a 9V battery powering the extension board, shown as both a schematic and a breadboard photo. — Official Freenove circuit — C Tutorial, Chapter 16 (Relay & Motor), page 147. The crop keeps Freenove's note about powering the motor from a 9V battery — that note is the heart of today's safety rule.

L293D In1 →GPIO 13 First direction signal — HIGH here drives the motor one way.

L293D In2 →GPIO 14 Second direction signal — always set opposite to In1.

L293D Enable1 →GPIO 12 The speed signal — PWM here sets how hard the motor drives.

Pot outer pins →3.3V and GND Feed the knob's track so the wiper can sweep between them.

Pot middle pin →GPIO 1 The knob's voltage lands here — the pin the code reads as A0.

Motor terminals →L293D Out1 and Out2 Where the chip feeds the battery's current to the motor.

9V battery line →Extension board power terminal Supplies the motor's current so the USB port never carries it.

Power the motor from the battery only. Freenove's warning is direct — powering the motor from the ESP32-S3 directly "may cause permanent damage to your ESP32-S3". Even spinning free, this motor draws about 0.2–0.3 A, far past what the board can supply. Connect the 9V battery to the extension board's power terminal and let it carry the motor.

Share one ground. An external supply must share a common ground with the board — the extension board's power terminal does this for you when it's wired as charted. 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 / 10 done

Keep USB unplugged, seat the ESP32-S3 on the GPIO extension board, and set the 9V battery aside until the wiring is checked.
Press the L293D into the breadboard so its notch faces the same way as the chart — the chip only works one way round.
Wire the direction pins — In1 → GPIO 13 and In2 → GPIO 14.
Wire the speed pin — Enable1 → GPIO 12.
Connect the motor's two terminals to the chip's Out1 and Out2.
Wire the potentiometer — outer pins to 3.3V and GND, middle pin to GPIO 1.
Clip the battery line onto the 9V battery and connect it to the extension board's power terminal, minding + and −.
Compare every wire to the chart — this is the day to be fussy about it — then plug in USB.
Open Sketch_16.1_Control_Motor_by_L293D.ino in Arduino IDE and upload it.
Switch on the extension board's power and sweep the knob slowly from end to end.

04 Read just enough code

Read the code

One sketch, three jobs — read the knob, work out speed and direction from the centre point, and hand both to the driver chip. Switch to MicroPython if you'd rather see the same idea in Python — the wiring never changes.

Sketch_16.1_Control_Motor_by_L293D.ino

int in1Pin = 13;      // Define L293D channel 1 pin
int in2Pin = 14;      // Define L293D channel 2 pin
int enable1Pin = 12;  // Define L293D enable 1 pin
int channel = 0;

boolean rotationDir;  // Define a variable to save the motor's rotation direction
int rotationSpeed;    // Define a variable to save the motor rotation speed

void setup() {
  Serial.begin(115200);
  pinMode(in1Pin, OUTPUT);
  pinMode(in2Pin, OUTPUT);
  pinMode(enable1Pin, OUTPUT);

  ledcAttachChannel(enable1Pin, 1000, 11, channel);//Set PWM to 11 bits, range is 0-2047
}

void loop() {
  int potenVal = analogRead(A0);      // Convert the voltage of rotary potentiometer into digital
  if (potenVal > 2048)
    rotationDir = true;
  else
    rotationDir = false;
  // Calculate the motor speed
  rotationSpeed = abs(potenVal - 2048);
  Serial.println(rotationSpeed);
  delay(100);
  driveMotor(rotationDir, constrain(rotationSpeed,0,2048));
}

void driveMotor(boolean dir, int spd) {
  // Control motor rotation direction
  if (dir) {
    digitalWrite(in1Pin, HIGH);
    digitalWrite(in2Pin, LOW);
  }
  else {
    digitalWrite(in1Pin, LOW);
    digitalWrite(in2Pin, HIGH);
  }
  // Control motor rotation speed
  ledcWrite(enable1Pin, spd);
}

analogRead(A0)Reads the knob. A0 is this board's alias for GPIO 1 — the same pin your wire lands on.

ledcAttachChannel(enable1Pin, 1000, 11, channel)Sets up PWM on the enable pin at 11 bits, so speed runs from 0 to 2047.

rotationSpeed = abs(potenVal - 2048)Speed is the knob's distance from centre; which side of 2048 it sits on picks the direction.

ledcWrite(enable1Pin, spd)Hands the speed to the chip — more on-time on Enable1 means more push through the motor.

Optional side path · same circuit

15.1_Motor_And_Driver/Motor_And_Driver.py

in1Pin=Pin(13, Pin.OUT)
in2Pin=Pin(14, Pin.OUT)

enablePin=Pin(12, Pin.OUT)
pwm=PWM(enablePin,10000)

adc=ADC(Pin(1))

try:
    while True:
        potenVal = adc.read()
        if (potenVal > 2048):
            rotationDir = 1;
        else:
            rotationDir = 0;
        rotationSpeed=int(math.fabs((potenVal-2047)//2)-1)
        driveMotor(rotationDir,rotationSpeed)
        time.sleep_ms(10)

pwm=PWM(enablePin,10000)PWM on GPIO 12 at 10 kHz with a 10-bit duty (0–1023) — the same idea as Arduino's 0–2047 on a smaller scale.

adc=ADC(Pin(1))Reads the knob straight from GPIO 1 — the pin the Arduino sketch calls A0.

Same wiring, same centre-zero knob. MicroPython's duty is 10-bit, so its speed formula halves the distance from centre to fit the 0–1023 range — different numbers, identical behaviour. 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

Small signals, borrowed muscle

A GPIO pin is a messenger. It can say a lot, and it can carry almost nothing. Today's chip is the porter that carries the load the message describes — and it is the first day the board commands real power instead of a single LED.

1

A pin's true size

A GPIO pin carries meaning on a trickle of current, a few milliamps at a delicate 3.3 volts. This motor wants 0.2 to 0.3 amps just to spin free — hundreds of times more than the pin can give.

2

A motor fights back

A spinning motor is also a small generator, and switching its current makes it kick back a voltage spike. That current draw and that kickback, fed straight into a GPIO pin, would damage the chip.

3

The porter with its own supply

The L293D runs from the motor's own 9V battery. It takes the pin's small signal and uses it to switch that heavy current, so the delicate logic and the motor's power stay on separate wires.

4

An H-bridge runs current either way

Inside sit four switches that route the battery through the motor one way or the reverse. In1 and In2 pick which pair closes, so the same motor spins forward or back with no rewiring.

5

PWM sets the throttle

Enable1 gates the bridge. A PWM signal there switches it on and off thousands of times a second, and the share of on-time is how hard the motor drives.

The model small signal + the chip's own battery = real motion · direction from which way current runs · speed from PWM duty

Two power worlds, one ground

The 9V battery moves the motor; USB feeds the board. The two supplies only agree on what HIGH and LOW mean because they share a ground on the extension board — that shared wire is what lets the chip read the board's signals.

Why reversing costs nothing

A DC motor spins the other way the moment its current reverses. The H-bridge does exactly that on command, so direction is a matter of which two switches close — never a second motor or a gearbox.

06 Know it worked

Test & debug

The proof today is the spinning shaft in front of you — Serial Monitor backs it up with a live speed number.

What you should see

Motor

Knob at centre — the motor sits still.
Turn one way — the shaft spins up, faster the further you go.
Sweep back through centre — it slows, stops, then spins the other way.
Serial Monitor at 115200 baud prints the speed number — 0 at centre, up to 2047 at the ends.

Expect a small still zone either side of centre — a motor needs a push of current before it beats its own friction, so the first sliver of knob travel does nothing. Today's challenge puts a number on exactly that.

If it doesn't

Motor never spins? Check the 9V battery on the extension board — its switch and its wiring — then the L293D's orientation by the notch.
Spins one direction only? A direction wire is loose or swapped — recheck In1 on GPIO 13 and In2 on GPIO 14.
Board resets or USB drops out? You're powering the motor from USB — stop and connect the 9V battery so the extension board carries the load.
Speed number stuck in Serial Monitor? Check the pot's middle wire on GPIO 1 — the pin the code reads as A0.

07 Make the idea yours

Try this: read the three signals in the motion

Same working circuit, two experiments that tie what you see the shaft do back to the three signals driving it. Both fit inside today's 30 minutes.

Map the signals to the motion

Add a Serial print of rotationDir next to the speed number, upload, and open Serial Monitor. Sweep the knob slowly from one end to the other. At centre both numbers fall to zero and the shaft stops. Cross centre and the direction flag flips — that is In1 and In2 swapping — and the shaft reverses. The further you turn, the higher the speed number Enable1's PWM carries, and the faster it spins. Every one of the three control pins is now visible in what the motor does.

Find the breakaway number

Creep the knob out from centre while watching Serial Monitor, in both directions. Note the number on screen the moment the shaft first turns — that is the push this motor needs to beat its own friction, the current floor below which the signal is real but the shaft stays still.

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-DAY22-MOTOR

Context packet

Open the JSON packet →

How the agent should behave: guide one physical connection at a time, wait for you to confirm, keep the 9V-battery rule front and centre, and explain the driver as the porter that carries current a GPIO pin never could — direction from the H-bridge, speed from PWM. Always check wiring, power, board, and port before changing code.

Make a motor
answer the knob

What you need

ESP32-S3 board

GPIO extension board

DC motor

L293D driver chip

Rotary potentiometer

Jumper wires (M/M)

Chart the circuit

Build it

Read the code

Small signals, borrowed muscle

A pin's true size

A motor fights back

The porter with its own supply

An H-bridge runs current either way

PWM sets the throttle

Two power worlds, one ground

Why reversing costs nothing

Test & debug

Try this: read the three signals in the motion

Map the signals to the motion

Find the breakaway number

Coach me through it

Lesson code

Context packet

Finished Day 22?

What you need

ESP32-S3 board Define

GPIO extension board Define

DC motor Define

L293D driver chip Define

Rotary potentiometer Define

Jumper wires (M/M) Define

Chart the circuit

Build it

Read the code

Small signals, borrowed muscle

A pin's true size

A motor fights back

The porter with its own supply

An H-bridge runs current either way

PWM sets the throttle

Two power worlds, one ground Define

Why reversing costs nothing Define

Test & debug

Try this: read the three signals in the motion

Map the signals to the motion Define

Find the breakaway number Define

Coach me through it

Lesson code

Context packet

Finished Day 22?

ESP32-S3 board

GPIO extension board

DC motor

L293D driver chip

Rotary potentiometer

Jumper wires (M/M)

Two power worlds, one ground

Why reversing costs nothing

Map the signals to the motion

Find the breakaway number