Stackr Robot Technical Specifications

Reference dimensions, connector pinouts, and wiring diagrams for the Stackr robot kit. Use this page when planning add-ons, writing custom sketches, or checking which Arduino pins are already used by the onboard components (motors, button).

Physical Dimensions

The Stackr chassis is a compact square platform designed for desktop robotics projects. The drawings below list overall length, width, and height, including the motor housings and top cover.

Stackr robot mechanical dimensions top side and front views — **Stackr-Size** — Mechanical outline with key dimensions. Footprint is **96 mm × 96 mm** (99 mm length including rear protrusion). Overall height is about **32 mm**. Use these values when designing mounts, enclosures, or custom brackets.

Pinout Summary

Stackr tutorials use the Arduino pin names (D3, A0, and so on) shown in the Arduino IDE for the Nano ESP32. The table below lists the main signals used on a stock Stackr build.

Function	Arduino pin	GPIO	Notes
Motor driver (TB6612)
Motor A PWM	D3	GPIO6	Right motor speed
Motor A IN2	D4	GPIO7	Right motor direction
Motor A IN1	D5	GPIO8	Right motor direction
Motor B IN1	D6	GPIO9	Left motor direction
Motor B IN2	D7	GPIO10	Left motor direction
Motor B PWM	D8	GPIO17	Left motor speed
Driver STBY	VIN	VIN	Standby = high (driver enabled)
Servo port (rear)
Servo 1 signal	D10	GPIO21	Primary servo (eg. Arm control)
Servo 2 signal	D9	GPIO18	Secondary servo (eg. Scoop/Claww control)
Servo port power	VIN	VIN	Battery voltage in
I2C port (rear)
SDA	D21 / A4	GPIO11	I2C data (e.g. Lidar)
SCL	D22 / A5	GPIO12	I2C clock
Port 3V3	3V3	3V3	3.3 V out for sensors
Input
Onboard button	D2	GPIO5	User definedb button
RC receiver (optional with adapter)
Channel 1	A0 / D17	GPIO1	Left–right joystick (steering)
Channel 2	A1 / D18	GPIO2	Forward–back joystick (throttle)
Channel 3	A2 / D19	GPIO3	Up button
Channel 4	A3 / D20	GPIO4	Down button
Channel 5	A6 / D23	GPI013	Left button
Channel 6	A7 / D24	GPIO14	Right button

Pins not listed are generally available for your own circuits. They can be accessed using the yellow connectors on the top of the chassis. Avoid reusing motor pins when stacking multiple add-ons. The servo pins and I2C pins can be used as general purpose pins assuming they are not used for their primary purpose.

Diagrams & Pinouts

Arduino Nano ESP32 installed on Stackr expansion headers — **Stackr-Arduino Nano** — Shows how the Arduino Nano ESP32 plugs into the blue expansion headers on the top of the chassis. The USB port faces left for programming; the power slide switch and blue user button are on the bottom corners of the base plate.

Arduino Nano ESP32 full pinout diagram — **Arduino Nano ESP32 - Pinout** — Official-style pinout for every pad on the Nano ESP32: power (`3V3`, `VIN`, `GND`), digital pins `D0`–`D24`, analog `A0`–`A7`, and special functions (I2C, SPI, UART). Cross-reference this chart when a tutorial refers to a pin that is not drawn on the Stackr-specific diagrams.

TB6612 motor driver wiring to Stackr motors — **Stackr-Motor Controller** — Wiring between the onboard TB6612FNG breakout and the two blue motors. Motor A (right) uses `A01`/`A02`; motor B (left) uses `B01`/`B02`. Control lines map to `D3`–`D8` and `D9` for standby, matching the motor tutorial sketches.

Stackr top view with user button pinout — **Stackr-Button-Pinout** — Top view of the expansion headers plus the user interface area. The blue button connects `D2` (GPIO5) to `GND` when pressed. The small slide switch on the lower left is the main power switch for the robot.

Stackr rear servo and I2C connector pinouts — **Stackr-Connectors-Pinout** — Rear edge connectors for add-ons. **Servo interface** (left): signal on `D10` and `D9`, plus `VIN` and `GND` for servo power. **I2C interface** (right): `SDA` on `D21`, `SCL` on `D22`, with `GND` and regulated `3V3` out for sensors such as the Lidar module.

RC transmitter channel to Arduino pin mapping — **Stackr-RC Controller.jpg** — Maps channels on the optional HotRC-style transmitter to Nano ESP32 analog inputs. Check the mapping of channels to Arduino Nano ESP32 pins in the table above.