Pepsi Bottle RC Boat


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.


Continue reading






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


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


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
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 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.


Continue reading

Chatting with a BC04 Bluetooth module using Android


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 and purchased it for experimenting.


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.



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

Continue reading

Simple Line Following robot using an Arduino


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

Continue reading