STM/NRF24 RC Car - WIP

The why

Wanted to build a small, custom RC car using modern microcontrollers and reliable 2.4 GHz communication. The goal is low-latency control, decent range, and the ability to add features later (telemetry, better battery management, etc.).

Motors & Drivetrain

Geared motor, 6V, 1000RPM: Aliexpress
Reasons for selecting:

Small size (HWL: 14mm × 12mm × 25mm)
Geared ratio for appropriate max speed (1,000 RPM with 1" diameter wheels gives a speed of approx. 4.7 km/h — reasonable for indoor use)
Decent torque for small chassis
Low current draw when free-running

Radio

nRF24L01+ modules are used for communication between transmitter and receiver. Chosen because:

Very low cost
Good range indoors (~50–100 m line-of-sight)
Low latency (~few ms round-trip possible with optimized code)
STM32 has plenty of SPI bandwidth to handle it

Microcontroller

STM32F103 (Blue Pill) on the car side for now — plenty of GPIO, timers for PWM motor control, SPI for nRF24, and ADC if telemetry (battery voltage, current sense) is added later.

Transmitter side likely using another STM32 or possibly ESP32 for joystick + screen in future revisions.

Current status (WIP)

Basic motor control and nRF24 packet receive working on breadboard. Still need to:

Design proper PCB for car chassis
Add H-bridge driver (DRV8833 or similar)
Implement failsafe (stop motors on lost connection)
Build transmitter with joysticks / hall-effect sticks
Test range and latency in real environment

More updates and schematics / photos coming as the project progresses.

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