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ST3215 Serial Bus Servo (19.5kg, 7.4V, 360°)

$17.90
SKU: SER0069
The ST3215 is a high-performance serial bus servo operating at 7.4V, delivering up to 19.5kg·cm of stall torque. It features a high-precision 12-bit magnetic encoder for 360° absolute positioning with a resolution of 0.088°.
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Introduction

The ST3215 is an intelligent, high-performance serial bus servo designed for advanced robotics and automation. It operates on a TTL serial bus interface, enabling control of up to 253 servos from a single port, which drastically simplifies wiring in complex multi-axis systems. The core of the ST3215 is a 12-bit high-precision magnetic encoder, offering 360° absolute positioning with exceptional accuracy (0.088°) that far exceeds traditional potentiometers. Key features include a powerful 19.5kg·cm stall torque, four distinct operating modes, and real-time feedback of critical parameters such as position, load, and temperature. This combination of strength, precision, and intelligence makes it an ideal actuator for demanding applications like robotic arms, quadruped robots, and humanoid robots.


High Torque & Durable Metal Gear Train

Engineered for strength and longevity, the ST3215 serial bus servo delivers a substantial stall torque of 19.5kg·cm at 7.4V. Its dual-axis, low-profile internal structure houses a robust 1:345 gear train made from a combination of copper and aluminum, ensuring efficient power transmission and high load capacity while maintaining low operational noise. The entire assembly is protected by a high-strength PA+GF housing, making it resilient enough for continuous use in dynamic robotic applications.


High-Precision 360° Magnetic Encoder

At the heart of its positioning system is a 12-bit magnetic encoder. Unlike conventional potentiometers, it can provide true 360° absolute position sensing without wear, achieving a high resolution of 4096 steps (0.088° per step). This allows for exceptionally smooth and precise motion control. The serial bus servo also supports multi-turn absolute positioning (±7 turns), enabling complex movements beyond a single rotation.


Intelligent Serial Bus Control

The ST3215 serial bus servo utilizes a half-duplex UART communication protocol, allowing up to 253 servos to be daisy-chained together and controlled via a single host I/O port. Each servo is assigned a unique ID (0-253), enabling individual command execution and data polling. This bus architecture significantly reduces cable clutter and simplifies the electronic design of sophisticated multi-degree-of-freedom (DOF) systems.


Four Versatile Operating Modes

To accommodate a wide range of applications, the serial bus servo features four programmable modes. The default Angle Servo Mode provides standard 0-360° absolute positioning with acceleration control for smooth motion. For continuous rotation, Speed Closed-loop Mode maintains a constant speed under varying loads, while Speed Open-loop Mode behaves like a standard DC motor. Finally, Stepping Mode allows for precise, incremental movements relative to the current position.

High-Precision Magnetic Encoder and Four Operating Modes


Real-Time Feedback & Comprehensive Protection

This smart servo offers closed-loop control by providing real-time feedback on position, speed, load, input voltage, current, and internal temperature. This data is critical for monitoring system health and creating adaptive behaviors. Furthermore, built-in protection mechanisms guard against over-stall, over-current, over-voltage, and over-heating, automatically disabling torque output to prevent damage and ensuring system reliability.

New Step Mode, Multi-Turn Large-Angle Precise Control and One-Key Center Calibration

Dual-Axis, Low-Profile Housing with Metal Gear Structure and Metal Servo Horn

Applications

  • Robotic arms
  • Educational robots
  • Quadruped robots
  • Humanoid robots
  • Small-scale sorting systems
  • Specification

    Electrical Characteristics

  • Operating voltage: 4-7.4V
  • No-load speed: 0.238s/60° (42RPM)@6V;0.192s/60° (52RPM)@7.4V
  • No-load current: 130mA@6V;[email protected]
  • Stall torque: 16.5kg.cm@6V;[email protected]
  • Stall current: 2A@6V;[email protected]
  • Standby current: 6mA
  • Rated load: 4kg.cm@6V;[email protected]
  • Rated current: 500mA@6V;[email protected]
  • Motor resistance: 2.5Ω
  • Torque constant (Kt): 8kg.cm/A
  • Mechanical Specifications

  • Dimensions: 45.2×24.7×35mm
  • Housing: PA+GF
  • Gear material: Copper
  • Bearing: Ball bearing
  • Sensor: 12-bit magnetic encoder
  • Rotation: 360°
  • Connector: 3-pin (Black-GND, Red-VCC, Blue-Signal/TTL)
  • Cable length: 15cm
  • Weight: 55±1g
  • Output shaft: 25T/OD5.9mm
  • Gear ratio: 1:345
  • Gear backlash: ≤0.5°
  • Output shaft screw: M3×6
  • Motor type: Coreless
  • Control Characteristics

  • Signal: Digital
  • Protocol: Half-duplex UART (8-bit, 1 stop bit, no parity)
  • ID range: 0-253
  • Baud rate: 38.4kbps-1Mbps (default: 1Mbps)
  • Control algorithm: PID
  • Midpoint: 180° (2048 steps)
  • Resolution: 0.088°
  • Rotation direction: Clockwise (0→4096)
  • Feedback: Load, position, operating speed, input voltage, operating current, operating temperature
  • Electronic Protection:
            Overload: Triggers when stalled torque exceeds 80% of stall value for 2s; cleared by sending new position command. Customizable torque threshold/duration.
            Overcurrent: Disables output when current >2A for 2s; cleared by sending new position command. Customizable current threshold/duration.
            Overvoltage: Activates when voltage >7.4V or <4V; auto-recovery within normal range. Customizable voltage range.
            Overheat: Disables torque output when temperature >70°C.
  • Operating Modes:
            Mode 0: Angle Servo (default; 0-360° absolute positioning)
            Mode 1: Speed Closed-loop Motor (maintains speed under load)
            Mode 2: Speed Open-loop Motor (speed drops under load)
            Mode 3: Stepping Mode (incremental motion from current position)
  • Multi-Turn Mode: ±7-turn absolute positioning at maximum precision (turn count not saved after power loss).
  • Center Calibration: One-click midpoint setting at any 360° position.
  • Reliability Testing

  • Load lifespan: >100,000 cycles
  • Motor noise: 45±5dB
  • Servo noise: 60±5dB
  • Storage temp: -30°C to +80°C
  • Operating temp: -20°C to +60°C
  • Signal Parameters

  • Max update rate: 1ms
  • High-level voltage: 2-5V
  • Low-level voltage: 0-0.45V
  • Documents

    Shipping List

  • ST3215 Serial Bus Servo -7.4V 19.5kg 360° ×1
  • Servo horn screw accessory kit ×1
  • 3-pin servo cable ×1
  • ST3215 Serial Bus Servo (19.5kg, 7.4V, 360°)
    $0.00