AVR based Etch A Sketch with Nokia 3310 LCD
Summary
This project allows one to use a universal IR remote to control an AVR based Etch A Sketch. For display, we use the Nokia 3310 LCD ($10 from SparkFun.com). The Etch A Sketch functionality is simply the ability to draw in a straight line up, down, left, right. The purpose of this project was to demonstrate the improvements to CC Dharmani’s NOkia 3310 library that allows per pixel access using a pixel buffer. The improved version has been included in the source of this project *. As originally written, the library worked great displaying fonts of two different sizes, clearing the screen, and drawing a boarder around the edges. Because of the way one must talk to the screen, it did not allow raw pixel access or random drawing. Doing so requires a local cache (buffer) of the pixels. This way, if you want to set a single pixel, you have the old value that you set to modify and write it back. The improvements shown here do just that. Additionally, we also have included a small tool to allow a .pgm file to be converted to a header for a splash screen. The additional routine to display the image is also included.
* Hopefully CC Dharmani and I will get together and put this library in a source repository to store continual improvements.
Details
For input, we use a 38kHz IR demodulating receiver. These can be picked up for $4 at RadioShack or $0.75 on Digikey (parts list below). Sparkfun.com also has a fancy one for $9.95. For display, we use our handy dandy Nokia 3310 replacement LCD. We talk to it using SPI. The arrow keys on the remote move the cursor and draw a line as it goes. The MENU or MUTE buttons swipe the screen.
Schematics
 Schematic - atmega8 with 3310 LCD and IR sensor |
 Nokia 3310 LCD Pinout |
Source Code
| 3310_routines.c 3310_routines.h | CC Darminitech’s Nokia 3310 LCD Library modified to support a local pixel buffer cache for individual pixel access. |
| avr-spiceduino-3310-drawing.tar.gz | Entire source code and firmware and pgmtoheader program - |
| pgmtoheader.c | Quickly hacked program to read in a 84×56 8-bits per pixel .pgm file and spit out a splash.h file for inclusion to an AVR project to display images. |
Steps for making splash screens (included as header files) with pgmtoheader.c:
- open a file that you want to display on your Nokia 3310 (black and white graphics are best) in GIMP or Photoshop
- resize to a height of 56
- use the thresholding tool to find a good value to use as the point between black and white. You probably will have to slide it back and forth until you get a good image.
- stretch/resize to 84×56
- save as .pgm (raw not ascii)
- open a hexeditor (I use khexedit) and hack off the header portion (or modify the code to skip over it)
- compile pgmtoheader with ‘gcc -o pgmtoheader pgmtoheader.c’
- run the pgmtoheader program on it with ‘./pgmtoheader /path/to/file.pgm > splash.h’
- you can now #include “splash.h” in the 3310_routines.c and call LCD_drawSplash() to display it.