Robit – DIY Mini Smart Cars Robot Development Platform Elecfreaks

Robit is a motherboard for a micro:bit based smart car.

It is compatible with MBOT. With most of the features of MBOT,  with the addition of 4 DC motor connectors, 2 stepper motor connectors and 8 PWM signal output. You can use it to drive PWM signal devices like servos. It has 8x G-5V-S digital signal connectors. Robit can gives you all the basic functions of MBOT. Additionally, you can extend its features with more sensors, motors, servos, stepping motors, etc.

Features

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• Compatible with MBOT chassis and sensors.
• Support 4 channels of DC motor and 2 channels of stepping motors.
• 8 PWM signal output connectors.
• 8 G-5V-S digital signal connectors.
• 4 G-5V-S analog signal connectors.
• Integrate frequently used modules like buzzer, rainbow LED, light sensor, infrared send and receive.

Pins & Connectors

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Introduction of Major Components

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RJ25 Connector

Robit has 4 RJ25 connectors. Each RJ25 connector has 6 touch points. These points respond to power, 2 IO ports and I2C ports separately. It is compatible with some sensors on mBOT.

 

RJ25 Connector	Pin mapping to micro:bit
J1	SCL(P19)/SDA(P20)/GND/5V/P13/P14
J2	SCL(P19)/SDA(P20)/GND/5V/P15/P16
J3	SCL(P19)/SDA(P20)/GND/5V/P1/P2 (support 5V analog input sensor)
J4	SCL(P19)/SDA(P20)/GND/5V/P3/P4 (support 5V analog input sensor)

 

GVS Standard Electric Brick Connector

In addition to the RJ25 connector, the I/O port on the micro:bit also interfaces with 5V components. P1/P2/P3/P4 supports 5V analog input sensors.

GVS Standard Servo Connector: S0~S7

You can connect 8 servos in total. This connector leads out from the chip PCA9685 and extends from the I2C connector on micro:bit instead of normal I/O ports.

DC Motor Connector: M1~M4

It allows you to connect 4 DC motors (max) at the same time. This connector leads out from the chip PCA9685 and extends from the I2C connector on micro:bit instead of normal I/O ports.

 

Stepping Motor Connector: STEP1 & STEP2

It enables you to connect (max) 2 stepping motors (28BYJ-48-5V).

 

Buzzer

The buzzer is connected to the P0 port on micro:bit.

 

Light Sensor

The light sensor onboard is connected to the P10 port on micro:bit.

 

Infrared Emitting Diode

This infrared emitting diode is connected to the P6 port on micro:bit.

 

Infrared Receiving Diode

This infrared receiving diode is connected to the P8 port on micro:bit.

 

Rainbow LED

Two rainbow LED beads are connected to the P12 port on micro:bit.

 

DC Power Connector

DC power connector supports 3.7V~4.2V DC power. It is usually connected to a battery holder with 4 AAA batteries.

 

Li-battery Connector

Li-battery connector supports 3.7V~4.2V li-battery.

 

Li-battery Indicator

This indicator tells you battery power information with status blinks. Blink once means 1 grid of power. And the full power has 4 grids. That means it will blink 4 times when the battery power is full.

 

USB Connector

This connector is only used to charge li-battery. It doesn’t support data transmit and its charging current is 500mA.

 

Quick Start

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Hardware Connection

Fix robit onto mbot car.
Connect left motor to M1 port, and right motor to M2 port.
Once completed, it looks like the following picture showed.

Programming

Click to open makecode, search the key word “robit” and add robit package.

 

Write your code to make the car in the forever block

to move forth and back for 3 seconds. Here’s the code:

 

 

You can see the whole program from the link here:https://makecode.microbit.org/_aXVAyx3dm585

Also, you can download the code directly from the page below:

Results

We can see our robit car moves forward for 3 seconds, and then backward 3 seconds. This round trip movement is repeated forever.

 

Parameter

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Project	Parameter
DC Power Input Voltage	DC 3.7-6V
Li-battery Input Voltage	DC 3.7-4.2V
USB Recharging Current	500mA
Extendable Analog IO Ports	4
Extendable Digital IO Ports	10
Max Stepping Motor Driven Quantity	8
DC Motor	4 Channels
Stepping Motor	2 Channels
Programmable LED Beads	2
Passive Buzzer	Support
Photocell Sensor	Support
Infrared Receive	Support
Infrared Send	Support
Dimension	90mm X 74mm
Net Weight	46g

 

Dimensions

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Packing List

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1 x Robit

Documents

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Robit User Guide

Measure Distance

Avoid Obstacle

Line Tracking

Run Around

Reversing Alarm

Colorful Light

Smart Car Light