Thomas Pfeifer has connected Nokia 6100 132×132 pixel 4096 color LCD to an AVR microcontroller. LCD is also used in Nokia 6100, 7200, 6610, 7250, and 6220. This display was relatively small by modern standards but was typical for phones of its time. The color depth of 4096 allowed for a range of colors to be displayed, but with limited color accuracy and depth compared to modern smartphone displays. He connected LCD to Atmega8 microcontroller: There are two display types: Epson chipset(S1D15G10) and Philips(PCF8833); The PCF8833 is a graphics display controller designed for color TFT displays with resolutions up to 176×220 pixels. It supported 4096 colors and used a serial interface to communicate with the phone’s main processor. The Epson S1D15G10 was not used in the Nokia 6100 specifically. The example code is written for Philips chipset. Firmware is written in AVR-GCC language, where images can be uploaded via serial cable. Also, there are few video view sample videos on how it AVR-3D-Engine works.
This AVR DDS generator can generate signals from 1Hz up to 65535Hz. Thanks to well known DDS algorithm, frequency limits can be much higher, but signal resolution drops in higher frequencies. The current range is enough for most audio signal equipment testing. DDS algorithm is written in software where Atmega8 runs at a maximum 16MHz. Several signal waveforms are available: sine, square, sawtooth, triangle, reverse sawtooth and pseudo-random noise. Signals are stored in lookup tables as the DDS algorithm requires. Signal output is organized via simple R-2R ladder DAC. LCD signal goes through the shift register; this way, only 3 MCU pins are used, while others serve for other purposes – buttons other outputs. The project is well documented PCB and source files included. The author states that he will build another DDS generator with improved control and variable signal amplifier at the output.