Shifter

Shifter is an add-on module for BlinkenMini or for LittleLights and BlinkenLEDs respectively. It takes over the CPU-intensive work of shifting a new b/w picture into the shift registers multiple times per millisecond to be able to show greyscale pictures with more than 50 Hz.

Therefore, Shifter receives the data to be displayed from a serial port in MCUF format (MCUF 18x8-1/256 to be exact) and generates a new b/w picture about every 200 microseconds using the microcontroller. This b/w picture is then shifted into the shift registers of BlinkenMini or respectivly LittleLights or BlinkenLEDs and is shown afterwards. 49 greyscale pictures shown in a row form a new greyscale picture with 8 greyscales about every 10 milliseconds. These greyscales are created using pulse width modulation with modulation with quadratic time relations and thus look much nicer as when using linear time relations.

Using Shifter, a BlinkenMini, LittleLights or BlinkenLEDs with parallelport connection (with or without greyscale extension) is converted into a serial display with 18x8 pixels and 8 greyscales that does need almost no CPU time and understands MCUF.

The data to feed into Shifter can be done very easily using the tool BlinkenOutput of the BlinkenLib. This tool received a MCUFstream from the network and outputs it on the serial port in the specified format.

In BlinkenMini configuration, Shifter is additionally able to read the stateof the 4 SNES pads and output it over the back channel of the serial port.

The current version of Shifter can be downloaded at:

http://1stein.blinkenarea.org/Shifter/

The archive contains next to the schematic diagrams for Shifterin BlinkenMini and respectively in LittleLights or BlinkenLEDs configuration (as PDF and as GSchem) the firmware for the microcontroller (ATtiny 2312 assembler).

-- StefanSchuermans - 19 Jun 2006