Major progress on LED display

After another evening at W88, there’s some good progress on the display.  First, there are four boards running in the display that I didn’t have to make!  I did etch them, but Bill and Karl ground them down to size and cut them apart.  Then Bob Magyar stopped by and was pressed into service applying solder paste, placing components for reflow and then cleaning up solder bridges, etc on the boards.  I did the reflow on the hot plate.

While the guys were prepping the boards, I ripped out the old rats nest of wire wrap column select lines now used as latch clocks and replaced it with a couple of much neater ribbon cable assemblies I’d made up at home.  Each ribbon carries 16 clocks (one 74154’s worth), so the two I put in will take care of the first 32 columns of latches.  I also ripped out the wire wrap tying the rows together for the rest of the first 32 rows.  Having the new latch clock loom in place makes connecting the clock for each new board much nicer.

I put in three boards that were completely ready to go from the last session, plus four of the boards Bill and Karl cut and Bob populated and tinned for a total of 20 running columns.  I thought the board tester was at the space, but it was at home, so the new boards went in without pre-test.  I did still fire the display up after each new board just in case, but all worked fine.  I brought the other six boards the guys cut back home.  Maybe I’ll finish those up at home  and etch some more doubles for others to prep for the next session.

It’s looking more and more like a display.  I touched up the crude hard coded scrolling code a little and put in a pattern for full text of “Workshop 88”, but couldn’t find it (and so thought incorrectly I’d forgotten to transfer it to the netbook I carry to the space).  That was probably because the dumb IDE doesn’t reread the sketchbook folder when you try to open a sketch – only when it starts.  I had the IDE open when I looked.  Boo.  Anyway, it’s looking good.

There’s nothing magic about scrolling right to left.  Given a buffer of pixel data, vertical scrolling should be doable.  Maybe the final code will include as part of the message coming in the serial port a mode byte specifying which of multiple display modes the message should be presented in.

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