Introduction: WiFi RC Rat

Picture of WiFi RC Rat

That plush rat is so nice! What if we could control it from the phone? :D

Step 1: Choosing the Electronic Parts

Picture of Choosing the Electronic Parts

To control it from the phone, we need:

- Bluetooth or WiFi module,

- microcontroller,

- 2 H bridges

- 2 motors

- battery

- Android phone or tablet

- RoboRemoFree app

Step 2: Choosing the WiFi Module

Picture of Choosing the WiFi Module

I chose the HUZZAH ESP8266 because:

- it has NodeMCU firmware and can run lua scripts, so we don't need an additional microcontroller

- it has at least 4 free GPIOs

- it can be powered from 3.5 to 16V

Step 3: Uploading Init.lua to ESP8266

The "init.lua" file contains the script that receives commands from WiFi and controls 4 GPIO pins that will be connected to H bridges. This file must be written to the ESP with filename "init.lua" so it will run at power on.

There are several ways to upload a file to ESP.

Here is how I do it (on Ubuntu Linux)

- Connect ESP to USB using an USB to Serial adapter (like FTDI)

- open CuteCom

- select device /dev/ttyUSB0 and baudrate 9600

- select LF line end and char delay 100ms

- click open device

- send some enters to make sure it is connected ok (it should answer with ">")

- open "luapaste.lua" with gedit and select all and copy

- paste in CuteCom and press enter and wait..............

- send the text "luapaste.lua"

- paste again the luapaste code

- now the ESP has "luapaste.lua" file, so next time you don't have to repeat these steps.

- close CuteCom

- open moserial Terminal

- select LF end

- click port setup and select select device /dev/ttyUSB0 and baudrate 9600 and uncheck handshakes

- click connect

- send some enters to make sure it is connected ok (it should answer with ">")

- send dofile("luapaste.lua")

- send the text init.lua

- paste the code from "init.lua" file

- send node.restart()

- it should answer something with "ESP8266 RC rat 1.0 powered by RoboRemo"

- close moserial Terminal

- disconnect the ESP

Step 4: Installing the RoboRemo Interface

Picture of Installing the RoboRemo Interface

Here is how to install the interface:

- install RoboRemoFree from Google Play

- copy the "rc rat.interface" file to the "roboremo" folder on the SD card

- open RoboRemoFree and choose menu -> interface -> import, and select the interface file

Step 5: Choosing the H Bridges, Motors and Wheels

Picture of Choosing the H Bridges, Motors and Wheels

The H bridges, motors and wheels should be small, so they can fit under the rat. Of course you can buy a dual H bridge, but it is much more fun to build it with SOT23 transistors (enjoy the videos). Building motors is not so easy, so I bought 2 Micro Metal Gearmotors (with gear ratio 30:1). I used 2 rubber stoppers as wheels.

Step 6: Connecting the Motors and Testing the H Bridges

Dual H bridge is alive and kicking :D

Step 7: Fixing All Together With Hotglue, Tape and Plastic Fasteners

Picture of Fixing All Together With Hotglue, Tape and Plastic Fasteners

Fixing all the electronics under the rat, and making some tests. The image shows how to connect the HUZZAH ESP to H Bridge. It is all powered by a LiPo cell. The foolproof diode is not the best solution, because it lowers the voltage to the ESP too (which already has one diode)

Step 8: The Rat in Action

Enjoy :)


chrisjlionel (author)2016-07-25

my mom would smash that. LOL. Nice work.

Slider2732 (author)2016-02-04

Haha neat project..the tank type controls work well and he's a speedy critter.

It's on the build list !

Slk_Stephane (author)2016-01-22

This could be a prank !!

DIY Hacks and How Tos (author)2016-01-22

HA! This could make for some many hilarious pranks.

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