Day 28: Thing 28: Charley plexed display
Today I made the software for some hardware that I built a while ago.
The origional question was if I got 15000 leds for next to nothing and it costs 4-15 per 8×8 array (with the 4$ solution also needing 4 to eleven additional parts) to drive them are we getting anywhere? I looked at 2 solutions before realizing that the leds were to dim to do much of anything that interested me. One solution was to drive the led rows with cmos shift registers and sink the columns using TPIC6 based shift registers.
The other solution is called charlyplexing.
The idea is to multiplex a series of leds in a way that maximizes the leds per io pin avaliable. The led connections are paired and driven one at a time depending on the direction of the output pins. The remaining pins are tri-stated out of the way. It is a pretty intense software complexity vs hardware problem.
As only one led in the array is on at a given time, multiplexing the leds into an array reduces the brightness significantly making my near free leds impractical for this application. (These are 5×6 array, the fonts i used were for 5×7 displays)
Last 5 posts by feurig
- Oh yeah. - March 22nd, 2008
- Day 29: Thing 29: One more thing.... - February 29th, 2008
- Day 27: Thing 27: The last of the 4 led arrays. - February 27th, 2008
- Day 26: Thing 26: PC Based Arduino Programmer. - February 26th, 2008
- Day 25: Thing 25: AntiSocial(ism) - February 25th, 2008