Flight Controller Design 2.1 - ESCs

Dual ESC Hardware Overview

This is a compact, dual-channel Electronic Speed Controller (ESC) designed to drive two independent 3-phase brushless motors using a single STM32G431CBT6 microcontroller. Each ESC channel includes its own power stage, current and voltage sensing, and input PWM/DShot control. The design supports both sensorless and sensored BLDC or FOC (Field-Oriented Control) operation.

The ESC is intended to be used in modular, stackable multirotor systems. Two ESC boards can be physically stacked to form a complete quadcopter ESC solution supporting four motors. A shared 12.6 V input power rail is distributed across the modules via 1.27mm header interconnects.

One ESC board provides a regulated 3.3 V output (via onboard LDO or switching regulator), supplying power to an externally mounted flight controller (FC). This eliminates the need for a separate power module. The FC connects directly to the top of the ESC stack and interfaces via standard signal headers for motor control and telemetry communication.

Key features include:

• Dual BLDC motor drive per module, compatible with DShot and PWM protocols
• Stackable design for 4-motor configurations (e.g., quadcopters)
• Shared 12.6 V power distribution between modules via backplane or board-to-board connectors
• Integrated 3.3 V buck converter on one module to power the FC
• Flight controller 1.27mm header interface

Microcontroller Unit (MCU)

• Model: STM32G431CBT6 (STMicroelectronics)
• Core: ARM Cortex-M4 @ 170 MHz with FPU
• System Clock: 16 MHz external crystal oscillator
• Purpose: Central controller for both ESCs; generates PWM, reads sensors, runs FOC or trapezoidal control.

Power Supply (Buck Converter)

• IC: TPS5430DDAR (Texas Instruments)
• Input Voltage (VIN): 12.6 V (designed for 3S)
• Output Voltage (VOUT): 3.3 V
• Purpose: Powers the MCU and logic circuits

MOSFET Power Stage

• FET Model: BSC0924NDI (Infineon)
• Quantity: 6 x 2 N-channel MOSFETs (3 per ESC)
• Configuration: Three half-bridges per motor
• Key Specs:

• • R_DS(on) ≈ 3.7 mΩ
  • V_DS max = 30 V
  • Current - Continuous Drain(Id) = 40A

Gate Drivers

• Model: IR2103STRPBF (Infineon)
• Quantity: 6 drivers (3 per motor, each driving one half-bridge)
• Features:

• • High-side and low-side drive
  • Bootstrap operation

Voltage Sensing

• Method: Voltage divider
• Ratio: 10kΩ / (10kΩ + 47kΩ) = ~0.175
• Equation:

• • V_MCU = V_PHASE × 0.175
• Purpose: Phase voltage monitoring for sensorless control, protection

Current Sensing

• Shunt Resistor: 1 mΩ
• Amplifier: INA180A3IDBVR (Texas Instruments)

• • Gain: 100 V/V
• Output to MCU:

• • V_MCU = I_PHASE × 0.1 V/A
• Power Limit: ~1 W → Max current ≈ 30 A

ESC 1 Pin Assignments

ESC 2 Pin Assignments

Programming / Debugging Interface

• Connector: Tag-Connect TC2030
• Interface: SWD (Serial Wire Debug)