How to Make a STM32 CNC 4 Axis?

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Creating a 4-axis CNC controller using an STM32 microcontroller involves several steps, including hardware selection, firmware development, motor control, and interfacing with G-code. Below is a structured guide to help you build your STM32-based 4-axis CNC machine.

How to Make a STM32 CNC 4 Axis? - Blog - Ampheo

1. Hardware Components Required

Component	Description
STM32 Board	STM32F4/F7/H7 (e.g., STM32F407, STM32F446) for high-speed PWM & timers
Stepper Motor Drivers	TMC2209, DRV8825, or A4988 (for NEMA 17/23 motors)
Stepper Motors	4x NEMA 17 or NEMA 23 (depends on load)
Power Supply	12V-36V (based on motor requirements)
CNC Shield	Optional (e.g., RAMPS 1.4, but STM32 needs custom wiring)
Limit Switches	Mechanical/optical for homing & safety
USB/Serial Interface	For G-code communication (UART/USB CDC)
Cooling System	Heat sinks/fans for drivers & motors

2. Firmware Development (STM32)

A. Development Environment Setup

Install STM32CubeIDE (or Keil/IAR with STM32 support).
Use STM32 HAL or LL libraries for peripheral control.
Enable TIM (Timer) for PWM (stepper control) and UART/USB for G-code.

B. Stepper Motor Control (Using STM32 Timers)

Configure 4x PWM channels (TIM1/TIM8 for advanced control).
Use Step/Direction control (TMC2209/DRV8825).

Example code for stepper control:

// Example: STM32 HAL for Step/Direction
void STEP_Pulse(uint8_t axis) {
    HAL_GPIO_WritePin(STEP_PORT, STEP_PIN, GPIO_PIN_SET);
    delay_us(10); // Short pulse
    HAL_GPIO_WritePin(STEP_PORT, STEP_PIN, GPIO_PIN_RESET);
}

C. G-code Parsing

Implement a G-code interpreter (Marlin/GRBL-like).
Parse commands like G0 X10 Y20 Z5 A90 (A = 4th axis).

Example simple G-code parser:

void parseGcode(char *gcode) {
    if (strstr(gcode, "G0")) {
        float x, y, z, a;
        sscanf(gcode, "G0 X%f Y%f Z%f A%f", &x, &y, &z, &a);
        moveTo(x, y, z, a); // Move steppers
    }
}

D. Motion Control (Bresenham Algorithm)

Use Bresenham’s line algorithm for smooth multi-axis movement.
Implement acceleration/deceleration (trapezoidal or S-curve).

3. Wiring Connections

STM32 Pin	Driver Pin	Function
`PA0-PA3`	`STEP`	Step pulses
`PA4-PA7`	`DIR`	Direction control
`PB0-PB3`	`EN`	Enable/disable motors
`UART1`	TMC2209 UART	For TMC2209 configuration
`PA8-PA11`	Limit Switches	X/Y/Z/A min/max

4. Software & Communication

Send G-code via:
- USB CDC (Virtual COM port)
- UART (from PC/Arduino)
- SD card (for standalone operation)
GUI Options:
- Universal G-code Sender (UGS)
- CNCjs (Node.js-based)
- Custom Python/C# app

5. Testing & Calibration

Test each motor individually (jog movement).
Calibrate steps/mm for each axis (e.g., $100=80.0 for X-axis).
Check limit switches for homing.
Verify G-code moves (e.g., G0 X10 Y10 Z5 A45).

6. Advanced Features (Optional)

Closed-loop control (with encoders).
TMC2209 UART control (for stealthChop/spreadCycle).
WiFi/Ethernet control (ESP32 as co-processor).
Touch probe for Z-axis calibration.

7. Example STM32 Projects & Libraries

GRBL-STM32 (Port of GRBL to STM32)
GitHub: grblHAL/STM32
Marlin 2.0 (Supports STM32F4)
GitHub: Marlin Firmware
Custom STM32 CNC Firmware
(Check OpenSTM32 forums)

Conclusion

By following this guide, you can build a 4-axis CNC controller using STM32 with smooth motion control and G-code compatibility. Start with basic stepper movements, then integrate G-code parsing and multi-axis coordination.