Raspberry Pi Pico VFD Motor Control with Quadrature Encoder

This repository provides a robust and modular solution to control a Variable Frequency Drive (VFD) using Modbus RTU communication and read encoder positions with a quadrature encoder. The project is designed with best practices and features asynchronous operations for seamless performance.

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Features

• Motor Control via VFD (CFW500):

  • Start, stop, and reverse the motor with precise RPM control.
  • Read motor speed (RPM) and status.
  • Reset VFD faults.

• Quadrature Encoder Integration:

  • Read encoder positions in steps or degrees.
  • Support for zero-calibration to set custom reference positions.
  • Handle "zero position" using the encoder’s Z signal.

• Configurable Verbose Levels:

  • Control console output:
    • 0: No output.
    • 1: Encoder position only.
    • 2: Motor actions and VFD status.
    • 3: Full details (encoder and motor/VFD statuses).

• Async Event Handling:

  • Non-blocking encoder reading and motor control using uasyncio.

• Modular Structure:

  • cfw500_modbus.py: VFD-related functions.
  • encoder.py: Encoder handling.
  • main.py: Main application logic.

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Requirements

Hardware

• Raspberry Pi Pico
• Omron E6B2-CWZ6C Quadrature Encoder (2000 PPR)
• WEG CFW500 VFD with Modbus RTU
• RS485 to UART converter
• Motor compatible with VFD

Connections

Encoder Pin	Pico Pin
A (Black)	GPIO16
B (White)	GPIO17
Z (Orange)	GPIO18
+5V (Brown)	VBUS (5V)
GND (Blue)	GND

Software

• Thonny IDE
• MicroPython firmware on Pico
• uasyncio library for async operations

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Getting Started

Installation

1. Clone the Repository:

   git clone https://github.com/<your-username>/<your-repo-name>.git
   cd <your-repo-name>

2. Prepare the Raspberry Pi Pico:

   • Flash the MicroPython firmware onto the Pico.
   • Ensure uasyncio is included (standard in MicroPython).

3. Upload Files:

   • Use Thonny IDE to upload main.py, cfw500_modbus.py, and encoder.py to the Pico.

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Usage

Commands

Motor Control

• start [rpm]: Start motor at the specified RPM (default: 1000 RPM).
• stop: Stop the motor.
• reverse [rpm]: Reverse motor at the specified RPM.
• set_speed [rpm]: Update motor speed reference.
• reset_fault: Reset VFD faults.

Encoder

• set_encoder_output [step|deg]: Set encoder output to steps or degrees.
• calibrate: Set current encoder position as zero.

Verbose Control

• set_verbose [0-3]: Adjust verbosity level.

Miscellaneous

• help: Show command list.
• exit: Exit the program.
• test: Run a test sequence.

Examples

1. Start motor at 1200 RPM:

   start 1200

2. Set encoder output to degrees:

   set_encoder_output deg

3. Calibrate the encoder:

   calibrate

4. Stop the motor:

   stop

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Code Overview

• main.py:

  • Main logic with asynchronous loops for encoder and motor control.
  • Command processing and zero-endstop integration.

• cfw500_modbus.py:

  • Modbus communication for VFD operations.
  • Functions for reading/writing parameters and fault handling.

• encoder.py:

  • Encoder handling with real-time position updates.
  • A/B/Z signal processing and calibration support.

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Troubleshooting

1. Motor does not start:

   • Check VFD connections.
   • Ensure Modbus parameters match cfw500_modbus.py.
   • Verify VFD power and fault status.

2. Encoder position not updating:

   • Verify wiring for A, B, Z signals (GPIO16, GPIO17, GPIO18).
   • Ensure encoder is powered and functional.

3. Verbose output issues:

   • Adjust verbosity using set_verbose [0-3].

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Contributing

1. Fork this repository.
2. Create a new branch for your changes.
3. Submit a pull request with a description of your updates.

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License

This project is licensed under the MIT License.

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Acknowledgments

• MicroPython development team
• Peter Hinch for encoder library contributions
• WEG for CFW500 documentation
• Omron for encoder specifications
• All contributors and testers