CABLEBOTTT

A hands-on STEAM workshop by FLU @ Fab Lab Barcelona.

Design, fabricate and program a cable-driven robot (cablebot). Participants build a small robot that travels along a cable using a rotating motor, and bring it to life by wiring up inputs (light, distance) and outputs (motor, LED, buzzer, servo). The activity combines mechanics + digital fabrication + computational thinking in an accessible, creative format.

Based on a yellow gearmotor driven from a Seeed Studio XIAO ESP32-C3, on a custom PCB.

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What you'll build

The cablebot comes in two behaviors, using the same hardware:

	Sketch A — autonomous	Sketch B — teleoperated
Idea	The robot decides for itself	You drive it from your phone
How	Follows light using 2 LDR sensors	Serves a webapp over its own WiFi
Inputs	2 light sensors (LDR)	Distance sensor (optional)
Outputs	Motor	Motor, color LED, buzzer, servo
Libraries	None	Adafruit NeoPixel + VL53L1X
Best for	Seeing a closed feedback loop	Programming your own behaviors

Both are fully documented — see Programming below.

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Folder structure

cablebottt/
├── README.md                        ← you are here (project index)
│
├── fabrication/                     ← everything you cut / print / mill
│   ├── ⟨laser_pieces.svg⟩           ← laser-cut structure (the 3 assembly pieces)
│   ├── ⟨mount_3d.stl⟩               ← 3D-printed parts (if any)
│   ├── pcb/                         ← custom PCB (KiCad project + Gerbers)
│   │   ├── fab26_cablebot.kicad_pro
│   │   ├── fab26_cablebot.kicad_sch
│   │   ├── fab26_cablebot.kicad_pcb
│   │   ├── gerber/                  ← ready-to-mill / ready-to-order
│   │   └── svg/fab26_cablebot-preview.svg
│   └── silkscreen/back_silkscreen.svg
│
├── code/
│   ├── cablebottt_laser/cablebottt.ino        ← Sketch A (autonomous)
│   └── cablebottt_web/cablebottt_web.ino      ← Sketch B (teleoperated)
│
├── docs/
│   ├── cablebottt_sketch_A_tutorial.md        ← how to program Sketch A
│   └── cablebottt_sketch_B_tutorial.md        ← how to program Sketch B
│
└── images/                          ← photos & reference
    ├── ⟨assembled_bot.jpg⟩
    ├── ⟨soldering_xiao.jpg⟩
    └── ⟨pcb_render.png⟩

⟨…⟩ = placeholder. Replace with your real filenames. If the layout above doesn't match how you organized the folder, adjust the paths — the section links below still work as long as the two docs/… tutorials keep their names.

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How to use this project

Do it in three stages. Each stage has its own detailed doc; this index just tells you the order.

1. Fabricate

Part	File	Process
Structure	fabrication/⟨laser_pieces.svg⟩	Laser-cut, then assemble the 3 pieces
Custom PCB	fabrication/pcb/gerber/	Mill or order from the Gerbers
Board	Seeed Studio XIAO ESP32-C3	Solder the header pins onto the PCB

Populate the PCB, solder the XIAO, attach the motor and the laser pointer, and assemble the laser-cut structure. Photos in images/.

2. Wire it up

The XIAO pinout, shared across both sketches:

Function	Pin	Used by
Motor driver 1 / 2	D9 / D10	both
LDR left / right	A1 / A0	Sketch A
NeoPixel (LED)	D7	Sketch B
Buzzer	D6	Sketch B
Servo	D8	Sketch B
Distance sensor SDA / SCL	D4 / D5	Sketch B

3. Programming

Pick the behavior and follow its step-by-step tutorial:

• Autonomous (follows light) → docs/cablebottt_sketch_A_tutorial.md No libraries needed. Upload and go.
• Teleoperated (phone webapp) → docs/cablebottt_sketch_B_tutorial.md Install 2 libraries, then connect your phone to the CABLEBOTTT WiFi network.

Both tutorials cover the one-time Arduino IDE + ESP32-C3 setup, so you only need to read it once.

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Quick start (already fabricated & flashed?)

1. Power the board over USB-C or the 9V battery.
2. Sketch A: shine a light near an LDR — the robot follows it.
3. Sketch B: on your phone, join WiFi CABLEBOTTT (password cablebottt), open http://192.168.4.1, and drive it.

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Originally created for a FAB26 Boston workshop. Repo: github.com/fablabbcn/cablebottt.