robotindex Waveshare RoArm-M2-S
A 4-DOF, ESP32-native desktop arm from Waveshare using ST3215 serial bus servos with metal internal gearing. "S" marks the standard-servo tier of the RoArm-M2 family, below the all-metal-case RoArm-M2-Pro. The Raspberry Pi visible in this unit's base is not a stock inclusion — Waveshare sells the arm and ESP32 driver board only, with the 40-pin header designed for a buyer-supplied Pi or Jetson.
waveshare.com/roarm-m2-s →
Image: user-submitted
Specs
Weight
~826 gexcluding table clamp; RoArm-M2-Pro is ~873g
Degrees of Freedom
4-DOF, 5 servosbase 360°, shoulder 180° (dual-servo drive), elbow 180°, hand 135°/270°
Payload
0.5 kg @ 0.5 mmanufacturer's own effective-payload figure
Controller
ESP32-WROOM-32runs web UI, ESP-NOW, JSON serial control standalone — no host computer required for basic use
Servos
ST3215nylon/fiberglass case, metal internal gearing, 12-bit magnetic encoder
Repeatability
≈ ±4 mmload-tested figure; a separate "0.088°" spec is the servo encoder's resolution, not arm accuracy
Workspace
Ø1090mm × 798mmhorizontal diameter × vertical reach
Compute Add-On
BYO Pi / Jetsonnot bundled; 40-pin header + camera mount bracket are provided for one
Reference Price
Waveshare's own listing prices the RoArm-M2-S/M2-Pro pair at $179.99–$299.99; the base M2-S specifically runs roughly $206–$260 across retailers (Amazon, AliExpress, RobotShop, RobotPiShop), with the all-metal-servo RoArm-M2-Pro upgrade running closer to $330. These figures cover the arm and ESP32 driver board only — no camera, no battery, and no Raspberry Pi or Jetson, all of which are separate purchases if you want the vision/ROS2 capabilities those add.
Insights
Waveshare's often-repeated "0.088°" precision figure is actually the servo encoder's angular resolution, not measured arm repeatability — the real, load-tested spec Waveshare's current product page lists is ±4mm. The core ESP32 firmware and Python SDK do carry genuine OSI-approved AGPL-3.0 licenses, but the separate ROS2/MoveIt2 workspace repo ships with no license file at all.
Firmware & Community
waveshareteam/roarm_m2
Open hardware and firmware repo for the RoArm-M2 desktop arm kit.
Specs compiled from Waveshare's official product page and wiki, its GitHub organization (roarm_m2, waveshare_roarm_sdk, roarm_ws_em0 — including direct inspection of each repo's LICENSE file), and retailer listings (RobotShop, RobotPiShop, ThinkRobotics, CNX Software's coverage) as of this build. Independent long-form reviews are sparse for this specific model; the Raspberry Pi shown in the submitted photo is inferred to be a buyer-added component, not a stock inclusion — no official Waveshare bundle with a Pi included was found.