Wednesday, 20 July 2011

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it is a simple AVR lcd display project


  • Decently-sized Breadboard (I used an 840-hole)
  • Breadboard hookup wires (I prefer stiff hookups for on-board work and longer flexible ones for ISP hookup and long runs)
  • Multimeter with conductivity testing mode (beep!) and DC voltage mode
  • Soldering iron - I have a 50-watt that I love.
  • An etching vessel - see PCB etching instructables.
  • A drill and PCB drill bits (I used sizes 65 and 75).  A mini drill press helps too.
  • A hot glue gun (optional, but barely - the wire broke twice on me with very little force applied)
  • An AVR ISP programmer (I built a USBTinyISP)
  • Helping hands (optional)


  • An ATtiny2313 (or 2313A, which is what I used - functionally equivalent)
  • An HD44780 LCD with a single row of pins
  • A 20-pin DIP socket
  • 7805 Voltage Regulator (you can definitely get away with a low-amperage one too, I just had these laying around)
  • A 100uF capacitor
  • A 10uF capacitor
  • A 330-ohm resistor
  • A 10K-ohm resistor
  • A 1N4004 diode (other diodes will probably work fine too - make sure to read the datasheet though)
  • A 5K linear potentiometer (or between a 1.5K and 2.5K resistor if you don't care about contrast adjustment - YMMV)
  • A 9V wired connector - preferably one that doesn't suck (I have suck ones.)
  • Breakable male header strip - you'll need 16 pins, but these usually come as 40-pin strips.


  • Etchant - again, see etching instructables
  • Solder, preferably very thin stuff.  I'm using .015 diameter.
  • PCB, single sided, whatever color you see fit.
  • Hot glue sticks - awwww yeah

Step 2The schematic

The schematic

Step 3Breadboard It

Breadboard It

Step 4Programming

Once you have it all hooked up, use git to grab the source code.  Here's the LCD library I wrote that you'll need to compile against:
git clone git://
You can view the source code for this project here:

Step 5Etch a board

Etch a board

Step 6Drill eet

Drill eet

Make sure to insert the IC socket the right direction.  Mine is currently backwards, which would be an issue if I didn't know the circuit like the back of my hand.

Step 7Solder it

Solder it
Now that it's all drilled, place your components.  Make sure to orient the capacitors correctly if necessary (I used electrolytics, which are polarized).  Remember - stripes look like minus characters - stripe to ground.  Make sure your diode is the right way - stripe away from positive voltage input.  Think of that stripe as a little wall for electricity - you don't want it coming in from the side the stripe is on.  The 7805 is oriented with the heatsink plate against the board, and if you look at it with the pins facing you, the left pin is VIN, the middle is GND, and the right is VOUT.  See the datasheet for further descriptions.  I ended up with 5.06V DC very steady  measured at my ATtiny VIN from a 9V battery said and done.

Step 9Glue stuff

apply glue to ensure the package is safe

tep 10Wear it !!!

Wear it like you stole it


sandeep said...

thank you for your project

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