Pepsi Bottle RC Boat

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My initial attempts at building an RC boat were a disaster. The first one I built used 433MHz RF¬†modules that somehow worked properly only on land. The moment I placed the boat in the water, the electronics would go crazy (probably due to EM noise) and I had to dive in to save the boat. So I decided my next one would use 2.4GHz RF modules, and this post here is about my successful attempt ūüėÄ

I used a 2 liter Pepsi bottle as the boat hull. For the RF link, I used nRF24L01+ RF modules , and the friendly Arduino as the boats brains.

boat_rx_electronics

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Messy-UNO

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messy_uno

 

This time I went about building my own low cost Arduino clone. To make sure that my design was consistent with arduino boards, I used Sparkfuns RedBoard design as a reference.

At first I wanted to attempt¬†a single layer layout. As you can see, I ended up using lots of jumpers ūüė¶ Also,¬† I customized the board to use SOT223 packages for the¬†voltage regulators (bottom layer). I had to use male header pins for the IO’s as my component stash was void of female headers.

Downloads: Eagle Schematic and Layout

Details:

The board¬†makes use of an atmega328 with an UNO bootloader. You can either purchase a bootloaded chip or¬†load the bootloader using a programmer. Here’s a list of sites that sell a pre-bootloaded Atmega328: Continue reading

4 wire resistive touch screens … how to break them

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After months of keeping my 4 wire resistive touch screen stored safely at the bottom of a small box, I felt a sudden urge to bring it out for experimentation. I was hoping to make a simple touch interface to control some stuff using my Arduino.

Excitedly I spent about half a day researching the touch screen. After reading a bunch of app notes and sample codes I felt confident enough to start.

Here are some helpful links:
Adafruit touch screen library
touch control panel by Practicalarduino.com
Touch screen example by Lars Schumann
Arduino and a Nintendo DS touch screen
Application note by Atmel
Application note by Texas Instruments
USB touchscreen mouse, example by Sparkfun
Get touchy, example on bildr

I had bought the touch screen (from digibay.in) without a separate connector. All it had was some delicate plastic film with the copper tracks. I would probably require connectors such as this or this to interface it to the Arduino.

I searched through some old motherboards, CD player PCB’s and Hard disk drives for a suitable connector, but couldn’t find any. Now, desperate to proceed, I began to carefully solder some wires directly to the tracks on the thin connecting film. I somehow regulated my tremors and managed to solder the wires. Then I applied a layer of hot glue just to strengthen the joint.

soldered_joint

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Chatting with a BC04 Bluetooth module using Android

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I wanted to control an Arduino UNO board using my android phones Bluetooth. The UNO board doesn’t have Bluetooth and so requires an external Bluetooth module. I found a small Bluetooth module (BOLUTEK BLK-MD-BC04-B) at digibay.in and purchased it for experimenting.

bc04_module

The BC04 module can be interfaced to your designs using UART. Before pairing with a device, the module enters into a command mode and can be configured using AT commands. Upon pairing with a device the module enters into a communication mode.

Documentation of the module:
BLK-MD-BC04-B Bluetooth Module Specification
BOLUTEK BLK-MD-BC04-B Bluetooth Module AT Commands

Testing the BC04 Bluetooth module:

Since I bought only one module I wanted to be extra careful, and so built a PCB for the module. The design is just an extension of the Application Circuit Diagram from the module specification file.

My_Board

Schematic

Eagle Schematic and Layout
BC04 Eagle Library
Schematic and Layouts as PDF

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Simple Line Following robot using an Arduino

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A long time back, during my college days, I had built a line following robot¬†using an 8051 microcontroller. After college that robot aged and died in my backyard shed. Ever since I’ve been planning on resurrecting her,¬†and finally did, using an Arduino Uno.


To make the robot platform I used two geared motors from an old toy crane, and a cheese tub.

Newborn Robot

Line follower robot platform

Here’s a view after attaching a front wheel and IR sensors.

Bottom view

Bottom view

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