Let There Be (Eco-Friendly) Light

A project log for Reverse Engineering Soneplex SPX-MPU SBC

Reverse engineering logs for salvaged MC68302 based SBC

plasmodePlasmode 01/16/2018 at 16:130 Comments

This is the simplified version of EASy68K compatible display.  Instead of 13 IC's, the simplified version has only 3 IC's.  It is certainly a lot easier to hand-wire!  The drawback is that it requires the microprocessor to refresh the display constantly since only one digit is displayed at any given time.  In this implementation, the display is driven by the foreground idle task when processor is not doing anything.  I kinda like that "drawback" feature because it indirectly shows the processor utilization--when the display starts to flicker, that means the processor is busily doing other works.  The power consumption is also significantly lower: it is about 150mA instead of 1 amp for the full-on 8-digit display. 

The program running on the display is Lee Davison's 'LED clock' taken from the example page: