YourITronics

What is a voice pad you might ask, well the answer is simple, just think of notepad, yes this is a voice recorder. This way you don’t need to carry paper and pen around to get your ideas, to-do’s noted, just record it and play it back.

The gadget described was made by the author for the 2006 Stellaris contest, it uses the LM3S811 microcontroller by Stellaris, SD card for storing the messages, and earpiece for the audio output, OLED display, it even has a buzzer to play ring tones, all hardware used is part of the Stellaris development board.

The messages are played back via the earphone piece, which is powered by PWM, so the audio output stage is a D class amplifier, the volume is controlled by a potentiometer.

The author states that the device can store up to 100 10-30s messages, I say that is plenty of room for personal use, and with the OLED display and menu it is a handy device.

The microcontroller used in this project can be hard to find, but the available source code makes it possible to port the application to another device.

Voice pad with LM3S811:[PDF] – [Download]

The project described below demonstrates the usage of LCD graphical display with the help of available demo source codes.

The LCD in the first place is a tricky device, first of all you need separate power for the back light because of the higher voltage, so the author used a break-out board from www.sparkfun.com (Nokia 6100 LCD including breakout board), this board has built in a DC/DC converter for boosting the voltage, you only need one 3.3V power source.

The second issue is the control of the LCD, fortunately these mass produced displays are well documented and frequently used by hobbyist, you find a bunch of demo code for almost any type of microcontroller. The author used the demo code found on the sparkfun site, with small modifications.

Let’s see the microcontroller, some years ago the favorite AVR used by newbies was the Atmega8, which was superseded by the Atmega48/88/168, it has the same rich features, and some improvements, this was the choice of the authors too(ATmega48).

After hooking up the LCD with the microcontroller, we need some data to display, the author used his flickr account for accessing some photos on the web, you can find the free API to access the data for phyton or other high level programming languages, the pictures after downloaded, were resized, and transferred via serial port to the microcontroller which displays the image. The rendering is quite slow because the data is sent pixel by pixel to the display, but hey, at the end you have a color picture downloaded from the web and displayed on a Nokia display.

Although it sounds to be great fun to build it, if you are a beginner, try something simpler, or at least load a simple picture from your PC.

Flickr + Nokia LCD: [Link]