Community project
Phone-Controlled Mini Drone
Generated with AIThis phone-controlled mini drone uses an ESP32 microcontroller to manage four brushless motors, an MPU-6050 IMU for orientation sensing, and a lightweight lithium polymer battery. The drone receives commands over WiFi from a web interface, allowing pilots to control throttle, pitch, and roll in real time.
This guide provides a complete wiring diagram, parts list, and step-by-step assembly instructions for building the four-arm frame, motor driver circuits, and power distribution system. Included firmware handles motor PWM control, IMU data fusion, and web-based command reception, with a safe startup procedure to verify all systems before flight.
Wiring diagram
Interactive · read-only
Pan and zoom to explore the wiring. Remix the project to edit it in your own workspace.
Parts list
Bill of materials| Component | Qty | Notes |
|---|---|---|
| DFRobot SEN0142 Fermion MPU-6050 6 DOF Sensor BreakoutMPU-6050 | 1 | DFRobot SEN0142 MPU-6050 breakout with 3-5 V board input, I2C interface, onboard I2C pull-ups, and i2cdevlib Arduino example coverage. |
| 8520 3.7 V Brushed Coreless Motor8520, CW/CCW to match propeller | 1 | A tiny brushed motor that spins the front-left propeller. |
| 8520 3.7 V Brushed Coreless Motor8520, CW/CCW to match propeller | 1 | A tiny brushed motor that spins the front-right propeller. |
| 8520 3.7 V Brushed Coreless Motor8520, CW/CCW to match propeller | 1 | A tiny brushed motor that spins the back-left propeller. |
| 8520 3.7 V Brushed Coreless Motor8520, CW/CCW to match propeller | 1 | A tiny brushed motor that spins the back-right propeller. |
| AO3400AAO3400A | 1 | 30V 5.7A N-channel enhancement-mode logic-level MOSFET in SOT-23-3L. Vgs(th) typically ~0.7V (max 1.45V at Id=250 uA), fully enhanced at Vgs=2.5V-4.5V. RDS(on) ~26 mOhm at Vgs=4.5V, ~38 mOhm at Vgs=2.5V. Driven directly by 3.3V or 5V microcontroller GPIO/PWM as a low-side switch for loads up to its Id and VDS limits. No firmware library required. |
| AO3400AAO3400A | 1 | 30V 5.7A N-channel enhancement-mode logic-level MOSFET in SOT-23-3L. Vgs(th) typically ~0.7V (max 1.45V at Id=250 uA), fully enhanced at Vgs=2.5V-4.5V. RDS(on) ~26 mOhm at Vgs=4.5V, ~38 mOhm at Vgs=2.5V. Driven directly by 3.3V or 5V microcontroller GPIO/PWM as a low-side switch for loads up to its Id and VDS limits. No firmware library required. |
| AO3400AAO3400A | 1 | 30V 5.7A N-channel enhancement-mode logic-level MOSFET in SOT-23-3L. Vgs(th) typically ~0.7V (max 1.45V at Id=250 uA), fully enhanced at Vgs=2.5V-4.5V. RDS(on) ~26 mOhm at Vgs=4.5V, ~38 mOhm at Vgs=2.5V. Driven directly by 3.3V or 5V microcontroller GPIO/PWM as a low-side switch for loads up to its Id and VDS limits. No firmware library required. |
| AO3400AAO3400A | 1 | 30V 5.7A N-channel enhancement-mode logic-level MOSFET in SOT-23-3L. Vgs(th) typically ~0.7V (max 1.45V at Id=250 uA), fully enhanced at Vgs=2.5V-4.5V. RDS(on) ~26 mOhm at Vgs=4.5V, ~38 mOhm at Vgs=2.5V. Driven directly by 3.3V or 5V microcontroller GPIO/PWM as a low-side switch for loads up to its Id and VDS limits. No firmware library required. |
| Lithium Ion Polymer Battery - 3.7V 400mAh3.7 V, 400 mAh, 25C or higher | 1 | Lithium-ion polymer (also known as 'lipo' or 'lipoly') batteries are thin, light, and powerful. The output ranges from 4.2V when completely charged to 3.7V. This battery has a capacity of 400mAh for a total of about 1.9 Wh. If you need a larger (or smaller!) battery, we have a full range of LiPoly batteries.The batteries come pre-attached with a genuine 2-pin 25mm long JST-PH connector as shown and include the necessary protection circuitry. Because they have a genuine JST connector, not a knock-off, the cable won't snag or get stuck in a matching JST jack, they click in and out smoothly. |
| 3.3v Buck Boost3.3 V output | 1 | TI TPS63030/TPS63031 high-efficiency single-inductor buck-boost converter family with 1A switches. Used to hold a regulated rail when battery voltage crosses above and below the target output. |
| Adafruit Micro-Lipo Charger (MicroUSB)single-cell LiPo USB charger | 1 | A USB charger board that safely charges one small lithium-polymer battery. |
| 100 Ohm Resistor100 Ω | 1 | A small resistor that protects one ESP32 motor-control output from switching spikes. |
| 100 Ohm Resistor100 Ω | 1 | A small resistor that protects one ESP32 motor-control output from switching spikes. |
| 100 Ohm Resistor100 Ω | 1 | A small resistor that protects one ESP32 motor-control output from switching spikes. |
| 100 Ohm Resistor100 Ω | 1 | A small resistor that protects one ESP32 motor-control output from switching spikes. |
| SS14 Schottky DiodeSS14 | 1 | A protective diode that absorbs the voltage kick from the front-left motor when it switches off. |
| SS14 Schottky DiodeSS14 | 1 | A protective diode that absorbs the voltage kick from the front-right motor when it switches off. |
| SS14 Schottky DiodeSS14 | 1 | A protective diode that absorbs the voltage kick from the back-left motor when it switches off. |
| SS14 Schottky DiodeSS14 | 1 | A protective diode that absorbs the voltage kick from the back-right motor when it switches off. |
| 100 kOhm Resistor100 kΩ | 1 | A resistor that holds the front-left motor switch safely off while the ESP32 is starting. |
| 100 kOhm Resistor100 kΩ | 1 | A resistor that holds the front-right motor switch safely off while the ESP32 is starting. |
| 100 kOhm Resistor100 kΩ | 1 | A resistor that holds the back-left motor switch safely off while the ESP32 is starting. |
| 100 kOhm Resistor100 kΩ | 1 | A resistor that holds the back-right motor switch safely off while the ESP32 is starting. |
Assembly
6 stepsMake the light four-arm frame
Fit motor_fl, motor_fr, motor_bl, and motor_br into a very light 85–100 mm plastic micro-quad frame. Treat the end with motor_fl and motor_fr as the front. Fit matching clockwise and counter-clockwise propellers only after all powered tests are finished; a propeller that faces the wrong way will lift poorly.
- Tip: Keep all four motors at the same height and keep the battery near the frame centre.
- ⚠ Do not fit the propellers while checking wiring or first using the phone controls — a motor can start unexpectedly and a propeller can cut skin or damage the board.
Build the four motor switches
For each motor, connect its positive wire to battery_1s BAT+. Connect its negative wire to that motor’s matching AO3400A Drain (D): motor_fl to mosfet_fl, motor_fr to mosfet_fr, motor_bl to mosfet_bl, and motor_br to mosfet_br. Connect every AO3400A Source (S) to battery_1s BAT- / GND. Solder one SS14 diode across each motor: its striped end (cathode) goes to the motor positive wire and its unstriped end (anode) goes to the motor negative/MOSFET-drain wire. This diode catches the electrical kick made when a motor stops.
- Tip: AO3400A parts are tiny: with the flat face and text facing you, check the seller’s pin marking before soldering. Use short, thick motor and battery wires.
- ⚠ A reversed SS14 diode becomes a direct short when the battery is connected and can overheat the battery or wires.
Wire the ESP32 motor controls
Connect GPIO25 through gate_r_fl (100 Ω) to mosfet_fl Gate (G), GPIO26 through gate_r_fr to mosfet_fr Gate (G), GPIO27 through gate_r_bl to mosfet_bl Gate (G), and GPIO32 through gate_r_br to mosfet_br Gate (G). For each MOSFET gate, connect its matching 100 kΩ resistor to GND: pulldown_fl, pulldown_fr, pulldown_bl, and pulldown_br. These resistors make sure every motor stays off while the ESP32 is starting.
- Tip: GPIO25 → 100 Ω → front-left gate (signal); GPIO26 → 100 Ω → front-right gate (signal); GPIO27 → 100 Ω → back-left gate (signal); GPIO32 → 100 Ω → back-right gate (signal).
- ⚠ Do not connect any motor directly to an ESP32 pin — the motor current will damage the board.
Add the level sensor
Mount imu_1 flat at the exact centre of the frame, with its printed axis arrows pointing toward the front motors. Connect VIN → 3V3 (power), GND → GND (ground), SDA → GPIO21 (data), and SCL → GPIO22 (clock).
- Tip: Use soft foam tape to reduce vibration, but do not let the sensor move relative to the frame.
- ⚠ Make sure VIN and GND are not swapped — swapped power can damage the sensor.
Connect the battery, charger, and 3.3 V supply
Connect battery_1s BAT+ to regulator_3v3 VIN and battery_1s BAT- to regulator_3v3 GND. Connect regulator_3v3 VOUT → ESP32 3V3 (power) and keep its GND connected to the shared GND (ground). Plug the battery into charger_1s BAT, and use only the charger’s USB socket for charging. The battery positive also feeds all four motor positive wires.
- Tip: Set the regulator output to exactly 3.3 V with a multimeter before connecting it to the ESP32. Keep the charger and regulator close to the battery connection.
- ⚠ Never connect the full 1-cell battery directly to the ESP32 3V3 pin — a fully charged battery can be 4.2 V and can damage it. Never charge a swollen, punctured, or hot LiPo battery.
Do the safe first power test
Leave all propellers off. Plug the ESP32 into USB, press Deploy in Schematik, then power the quad from its battery. On the phone, join Wi-Fi network MicroQuad using password flysafe1, then open 192.168.4.1 in the phone browser. Press ARM and use very small throttle steps to confirm each motor is in the expected corner; press STOP after each test.
- Tip: If a motor spins in the wrong direction for its propeller, reverse that motor’s two wires at the motor. Keep the model secured on the bench for this test.
- ⚠ The phone page stops the motors if commands stop arriving for one second, but it is not a substitute for removing propellers during setup. Test outdoors in an open area only after the propellers are fitted.
Pin assignments
Board wiring reference| Pin | Connection | Type |
|---|---|---|
| 3V3 | imu_1 VIN | power |
| GND | imu_1 GND | ground |
| GPIO 21 | imu_1 SDA | i2c |
| GPIO 22 | imu_1 SCL | i2c |
| EXT | battery_1s BAT+ → 8520 3.7 V Brushed Coreless Motor + | power |
| GND | battery_1s BAT- | ground |
| EXT | motor_fl - → AO3400A Drain (D) | power |
| EXT | motor_fr + → Lithium Ion Polymer Battery - 3.7V 400mAh BAT+ | power |
| EXT | motor_fr - → AO3400A Drain (D) | power |
| EXT | motor_bl + → Lithium Ion Polymer Battery - 3.7V 400mAh BAT+ | power |
| EXT | motor_bl - → AO3400A Drain (D) | power |
| EXT | motor_br + → Lithium Ion Polymer Battery - 3.7V 400mAh BAT+ | power |
| EXT | motor_br - → AO3400A Drain (D) | power |
| GND | mosfet_fl Source (S) | ground |
| GND | mosfet_fr Source (S) | ground |
| GND | mosfet_bl Source (S) | ground |
| GND | mosfet_br Source (S) | ground |
| GPIO 25 | gate_r_fl A | digital |
| EXT | gate_r_fl B → AO3400A Gate (G) | digital |
| GPIO 26 | gate_r_fr A | digital |
| EXT | gate_r_fr B → AO3400A Gate (G) | digital |
| GPIO 27 | gate_r_bl A | digital |
| EXT | gate_r_bl B → AO3400A Gate (G) | digital |
| GPIO 32 | gate_r_br A | digital |
| EXT | gate_r_br B → AO3400A Gate (G) | digital |
| EXT | pulldown_fl A → AO3400A Gate (G) | digital |
| GND | pulldown_fl B | ground |
| EXT | pulldown_fr A → AO3400A Gate (G) | digital |
| GND | pulldown_fr B | ground |
| EXT | pulldown_bl A → AO3400A Gate (G) | digital |
| GND | pulldown_bl B | ground |
| EXT | pulldown_br A → AO3400A Gate (G) | digital |
| GND | pulldown_br B | ground |
| EXT | diode_fl Cathode → Lithium Ion Polymer Battery - 3.7V 400mAh BAT+ | power |
| EXT | diode_fl Anode → AO3400A Drain (D) | ground |
| EXT | diode_fr Cathode → Lithium Ion Polymer Battery - 3.7V 400mAh BAT+ | power |
| EXT | diode_fr Anode → AO3400A Drain (D) | ground |
| EXT | diode_bl Cathode → Lithium Ion Polymer Battery - 3.7V 400mAh BAT+ | power |
| EXT | diode_bl Anode → AO3400A Drain (D) | ground |
| EXT | diode_br Cathode → Lithium Ion Polymer Battery - 3.7V 400mAh BAT+ | power |
| EXT | diode_br Anode → AO3400A Drain (D) | ground |
| EXT | regulator_3v3 VIN → Lithium Ion Polymer Battery - 3.7V 400mAh BAT+ | power |
| GND | regulator_3v3 GND | ground |
| 3V3 | regulator_3v3 VOUT | power |
| EXT | charger_1s VCC → USB charging cable 5 V | power |
| GND | charger_1s GND | ground |
| EXT | charger_1s BAT → Lithium Ion Polymer Battery - 3.7V 400mAh BAT+ | power |
Firmware
ESP32main.cppDeploy to device
#include <Arduino.h>
#include <Wire.h>
#include <WiFi.h>
#include <WebServer.h>
#include <MPU6050.h>
// Forward declarations
int clampPwm(int value);
void motorWrite(int fl, int fr, int bl, int br);
void stopMotors();
void updateImu();
void updateMotors();
void handleCommand();
constexpr int MOTOR_FL_PIN = 25;
constexpr int MOTOR_FR_PIN = 26;
constexpr int MOTOR_BL_PIN = 27;
constexpr int MOTOR_BR_PIN = 32;
constexpr int I2C_SDA_PIN = 21;
constexpr int I2C_SCL_PIN = 22;
constexpr int PWM_FREQ = 20000;
constexpr int PWM_RESOLUTION = 8;
constexpr int PWM_MAX = 255;
constexpr int MOTOR_FL_CHANNEL = 0;
constexpr int MOTOR_FR_CHANNEL = 1;
constexpr int MOTOR_BL_CHANNEL = 2;
constexpr int MOTOR_BR_CHANNEL = 3;
constexpr uint32_t COMMAND_TIMEOUT_MS = 1000;
WebServer server(80);
MPU6050 imu;
bool armed = false;
int throttleCommand = 0;
int pitchCommand = 0;
int rollCommand = 0;
uint32_t lastCommandMs = 0;
uint32_t lastImuMs = 0;
float pitchDeg = 0.0f;
float rollDeg = 0.0f;
const char PAGE[] PROGMEM = R"rawliteral(
<!doctype html><html><head><meta name="viewport" content="width=device-width,initial-scale=1"><style>
body{font-family:Arial;text-align:center;background:#18202a;color:#fff;margin:0;padding:18px}button{font-size:20px;margin:7px;padding:16px 20px;border-radius:10px;border:0}#arm{background:#28a745;color:white}#stop{background:#d33;color:white}.row{display:flex;justify-content:center;gap:8px;flex-wrap:wrap}.hint{color:#cbd5e1}
</style></head><body><h2>Micro Quad Control</h2><p class="hint">Remove propellers for the first test.</p>
<div class="row"><button id="arm" onclick="send('arm')">ARM</button><button id="stop" onclick="send('stop')">STOP</button></div>
<h3>Throttle</h3><div class="row"><button onclick="send('t+20')">+20</button><button onclick="send('t-20')">-20</button></div>
<h3>Lean direction</h3><div class="row"><button onclick="send('r-15')">LEFT</button><button onclick="send('p+15')">FORWARD</button><button onclick="send('r+15')">RIGHT</button></div><div class="row"><button onclick="send('p-15')">BACK</button><button onclick="send('center')">LEVEL</button></div>
<p id="s">Connecting...</p><script>function send(c){fetch('/cmd?c='+encodeURIComponent(c)).then(r=>r.text()).then(t=>document.getElementById('s').textContent=t).catch(()=>document.getElementById('s').textContent='Connection lost - motors will stop');}setInterval(()=>send('keep'),400);</script></body></html>
)rawliteral";
int clampPwm(int value) { return constrain(value, 0, PWM_MAX); }
void motorWrite(int fl, int fr, int bl, int br) {
ledcWrite(MOTOR_FL_CHANNEL, clampPwm(fl)); ledcWrite(MOTOR_FR_CHANNEL, clampPwm(fr));
ledcWrite(MOTOR_BL_CHANNEL, clampPwm(bl)); ledcWrite(MOTOR_BR_CHANNEL, clampPwm(br));
}
void stopMotors() { motorWrite(0, 0, 0, 0); }
void updateImu() {
uint32_t now = millis();
float dt = (lastImuMs == 0) ? 0.01f : (now - lastImuMs) / 1000.0f;
lastImuMs = now;
int16_t ax, ay, az, gx, gy, gz;
imu.getMotion6(&ax, &ay, &az, &gx, &gy, &gz);
float accelRoll = atan2f((float)ay, (float)az) * 57.2958f;
float accelPitch = atan2f(-(float)ax, sqrtf((float)ay * ay + (float)az * az)) * 57.2958f;
rollDeg = 0.98f * (rollDeg + ((float)gx / 131.0f) * dt) + 0.02f * accelRoll;
pitchDeg = 0.98f * (pitchDeg + ((float)gy / 131.0f) * dt) + 0.02f * accelPitch;
}
void updateMotors() {
if (!armed || millis() - lastCommandMs > COMMAND_TIMEOUT_MS) { armed = false; stopMotors(); return; }
float pitchError = (float)pitchCommand / 10.0f - pitchDeg;
float rollError = (float)rollCommand / 10.0f - rollDeg;
int pitchCorrection = constrain((int)(pitchError * 3.0f), -35, 35);
int rollCorrection = constrain((int)(rollError * 3.0f), -35, 35);
motorWrite(throttleCommand - pitchCorrection - rollCorrection,
throttleCommand - pitchCorrection + rollCorrection,
throttleCommand + pitchCorrection - rollCorrection,
throttleCommand + pitchCorrection + rollCorrection);
}
void handleCommand() {
String c = server.arg("c");
lastCommandMs = millis();
if (c == "arm") { armed = true; throttleCommand = 0; pitchCommand = 0; rollCommand = 0; }
else if (c == "stop") { armed = false; throttleCommand = 0; }
else if (c == "center") { pitchCommand = 0; rollCommand = 0; }
else if (c.startsWith("t")) throttleCommand = constrain(throttleCommand + c.substring(1).toInt(), 0, 210);
else if (c.startsWith("p")) pitchCommand = constrain(pitchCommand + c.substring(1).toInt(), -80, 80);
else if (c.startsWith("r")) rollCommand = constrain(rollCommand + c.substring(1).toInt(), -80, 80);
String reply = armed ? "ARMED | throttle " + String(throttleCommand) + " | pitch " + String(pitchDeg,1) + " | roll " + String(rollDeg,1) : "STOPPED";
server.send(200, "text/plain", reply);
}
void setup() {
Serial.begin(115200);
Wire.begin(I2C_SDA_PIN, I2C_SCL_PIN);
imu.initialize();
ledcSetup(MOTOR_FL_CHANNEL, PWM_FREQ, PWM_RESOLUTION);
ledcSetup(MOTOR_FR_CHANNEL, PWM_FREQ, PWM_RESOLUTION);
ledcSetup(MOTOR_BL_CHANNEL, PWM_FREQ, PWM_RESOLUTION);
ledcSetup(MOTOR_BR_CHANNEL, PWM_FREQ, PWM_RESOLUTION);
ledcAttachPin(MOTOR_FL_PIN, MOTOR_FL_CHANNEL); ledcAttachPin(MOTOR_FR_PIN, MOTOR_FR_CHANNEL);
ledcAttachPin(MOTOR_BL_PIN, MOTOR_BL_CHANNEL); ledcAttachPin(MOTOR_BR_PIN, MOTOR_BR_CHANNEL);
stopMotors();
WiFi.mode(WIFI_AP);
WiFi.softAP("MicroQuad", "flysafe1");
server.on("/", [](){ server.send_P(200, "text/html", PAGE); });
server.on("/cmd", handleCommand);
server.begin();
}
void loop() {
server.handleClient();
updateImu();
updateMotors();
delay(5);
}“Deploy to device” opens this project in Schematik, where you can flash it to your board over USB.
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