ST3215 Servo Python Library

This project provides a simple Python interface for controlling the ST3215 bus servo using the Waveshare Bus Servo Adapter.

It builds upon the original Waveshare examples and restructures them into a cleaner, easier-to-use format—similar to how standard hobby servos are used.

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Features

• Easy-to-use Python API for ST3215 servos
• Based on Waveshare communication protocol
• Simplified commands for position, speed, and control
• Designed for quick integration into robotics projects

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Background

The original Waveshare resources for ST3215 servos were difficult to locate and not well structured. This repository consolidates the required code and improves usability for developers.

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Requirements

• Python 3.x
• Waveshare Bus Servo Adapter
• ST3215 Servo
• pyserial==3.5

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Installation

git clone https://github.com/Saksham-Agarwal/ST3215-Servo-Python.git
cd ST3215-Servo-Python

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Setup (Virtual Environment) [for windows]

python -m venv .venv
.venv\Scripts\activate

# Install dependencies
pip install -r requirements.txt

# Deactivate environment
deactivate

Setup (Virtual Environment) [for ubuntu]

python3 -m venv .venv
source .venv/bin/activate
# Install dependencies
pip install -r requirements.txt

# Deactivate environment
deactivate

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Example

from servo_control.ST3215 import ST3215

bus = ST3215("COM5")

ids = bus.scan()
print(ids)

bus.write_angle(ids[0], 2048)

bus.close()

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API Reference

ST3215(device_name, baudrate=1000000, speed=2400, acceleration=50)

Initializes the servo bus connection.

• device_name: Serial port (e.g., COM5, /dev/ttyUSB0)
• baudrate: Communication speed (default: 1 Mbps)
• speed: Default movement speed
• acceleration: Default acceleration

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check_servo(servo_id)

Checks if a servo is connected and responding.

• servo_id: ID of the servo
• Returns: True if detected, else False

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scan(start=0, end=20)

Scans a range of IDs and finds connected servos.

• start: Starting ID
• end: Ending ID
• Returns: List of detected servo IDs

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change_id(current_id, new_id)

Changes the ID of a servo.

• current_id: Existing ID
• new_id: New ID (0–253)

⚠️ Important: Only one servo should be connected while performing this operation.

• Returns: True if successful

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write_angle(servo_id, angle)

Moves the servo to a specific position.

• servo_id: Servo ID
• angle: Target position (raw value, typically 0–4095)

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read_angle_speed(servo_id)

Reads current position and speed of a servo.

• servo_id: Servo ID
• Prints position and speed

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wheel(servo_id, rot_speed)

Sets the servo to continuous rotation mode.

• servo_id: Servo ID
• rot_speed: Rotation speed (sign = direction, magnitude = speed)

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ReadTemp(servo_id)

Returns Temperature value in celsius.

• servo_id: Servo ID

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ReadCurrent(servo_id, rot_speed)

Returns current draw of the servo motor in mA.

• servo_id: Servo ID

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close()

Closes the serial port connection.