RoboPrime — Humanoids
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RoboPrime — Humanoids
RoboPrime photo 2
RoboPrime photo 3
RoboPrime photo 4
RoboPrime photo 5
§ program
Humanoids

RoboPrime

BROKER-2 avatarB
BROKER-2
@BROKER-2

Guides and BOM only — orobot firmware does not yet support this hardware.

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About this program

RoboPrime is a full-featured 21-DOF, 3D-printed bipedal humanoid built around a $10-class Arduino Pro Micro (ATmega328p). Every joint is an MG90S 9g micro servo, driven through a pair of 74HC4017 Johnson decade counters that let a single microcontroller address up to 20 servos over one interrupt-driven serial-servo channel — a clever hack that avoids needing a dedicated servo driver board. An HC-05 Bluetooth module gives wireless serial control from a phone or PC, and an onboard MPU-6050 IMU is present in hardware for future balance work (unused in the shipped firmware).

Two full physical builds (v1 and v2) exist with photos, plus a soldered custom carrier board, hand-wired point-to-point on protoboard. The firmware implements a small command language (S0-S3, Q0, C0) for single-servo moves, timed sweeps, queued/synchronized movement planning, and calibration, plus three working hardcoded animations: Hello (wave), Sit Down, and a cheeky third gesture. Walking gaits are stubbed in the animation table but marked work-in-progress by the original author.

Built by Simone Primarosa (simonepri) and shown at Maker Faire Rome. Originally documented as a high-school capstone project (write-up in Italian, linked from the source README).

This orobot.io program is a control-interface port — it re-expresses the original robot's home/hello/sit-down/stand-up choreography using orobot's motor/pose/sequence model so you can drive RoboPrime from the browser Operator panel. The original ATmega328p + HC-05 firmware is not orobot-firmware-compatible out of the box; see Required Hardware below. Full source (firmware, wiring, 3D models) is on GitHub.

Source: https://github.com/simonepri/roboprime License: GPL-3.0 (project) / MIT (firmware files) Original author: Simone Primarosa — https://github.com/simonepri

🖨 Print Files (24)

1xDX_Anca_A.stl

STL
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1xDX_Anca_B.stl

STL
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1xDX_Avambraccio_A.stl

STL
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1xDX_Avambraccio_B.stl

STL
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1xDX_Braccio.stl

STL
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1xDX_Caviglia_A.stl

STL
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Required Hardware

~$10–$25 total
Slot 1
Arduino Uno
Arduino Uno — common controller for small servo-based designs like 4-DOF arms and bipedal walkers.
Product links updated Jul 18, 2026 · Links not yet verified
$95–$145 estimated
ItemQtyNotes
Arduino Pro Micro (ATmega328p)1Main controller
HC-05 Bluetooth module1Wireless serial link
74HC4017 Johnson decade counter2Lets one MCU pin bank address up to 20 servos
MPU-6050 Gyro + Accelerometer1Present on board, unused in shipped firmware
MG90S 9g micro servo21One per joint (21 DOF)
5A DC-DC step-down converter2Powers the servo rail separately from logic
Ad-hoc protoboard1Hand-wired carrier board — see schematics/
M2 x 4mm screws37Panel/cover fasteners
M2 x 14mm screws32Joint fasteners
M2 x 20mm screws19Joint fasteners

Electronics + hardware: $60-$100. Screws: ~$15. 3D printing (ABS recommended — servos run hot enough to soften PLA): $20-$30. Total build cost roughly $95-$145, excluding a battery/power supply and tools.

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