Still a prototype.
No RC control, altitude sensor, battery monitor, or independent motor kill input. A timed PWM ramp cannot guarantee a controlled landing.
ARMAN ISLAM / SUMMER 2025
A lot to understand
A drone built from scratch, right down to the code that talks to the hardware.
A CONCEPT IN MOTION · ILLUSTRATION
How does code make it move? ↓CONTROLLERSTM32F103RB
CORE CLOCK72 MHz
MOTOR PWM20 kHz
APPROACHZero HAL
01 / THE IDEA
How much of a flying
machine can you build yourself?
That question became a summer project.
Over summer break in 2025, I set out to build a drone and understand the system beneath it. The firmware is written from scratch, including the peripheral drivers. Only the startup and linker files are reused.
This is the record of that process: a bare-metal quadcopter, from the first register writes to the motor-control loop.
ARMAN ISLAM / BUILDER & DEVELOPER02 / THE HARDWARE
Built on the bench.
A compact frame. Four brushed motors. A controller with nothing hidden behind a library.
- Microcontroller
- STM32F103RB
- Motion sensor
- MPU6050 · I²C
- Motor drivers
- LP9110s
- Propellers
- DJI Tello
- Motor type
- Brushed DC
- Frame dimensions
- 12 × 12 × 3 in
03 / TALKING TO THE HARDWARE
Code goes in.
Something real happens.
A driver is the translator between software and electronics. In this project, I wrote that translator myself: C code writes directly to the STM32’s hardware registers, which configure the peripherals connected to the drone.
01 / YOUR C CODE
motor_set(0, 500);
Ask motor 0 for 50% PWM duty.
02 / STM32 REGISTERTIM2 → CCR1
Write 1800 into the timer’s compare register.
03 / THE REAL WORLDMotor driver → motor
The timer produces a 20 kHz waveform. The motor driver switches power to the motor.
This is what “bare metal” means: the driver touches the hardware registers directly. There’s no HAL doing the register configuration for you.
REAL SOURCE, SIMPLIFIED EXAMPLE
This diagram explains the signal path; it does not control a drone. Actual motors stay off in the default firmware build.
See this driver on GitHub ↗04 / WORK IN PROGRESS
Engineering is iteration.
The current firmware supports an opt-in timed attitude-control run. Sensor errors, excessive tilt or rotation, and late loop iterations stop the motors. Controller gains still need bench tuning.
More control. More checks.
RC control and additional assertions and safety cases are planned. Validation starts with propellers removed, followed by a restrained rig and external power cutoff.
FOLLOW THE BUILD
The details are
in the source.
Explore the repository ↗Firmware, wiring, frame files, and project notes.