This evening, as soon as Evelyn was supposed to go to bed, I snuck off to the basement.  The 2560 circuit board has a lot of holes in it, so I cheated and drilled out only the holes I would need to get the board to power up for me.  There were seven vias and ten holes for the programming header.  There were also, of course, 100 very tiny pins to solder. As soon as I finished soldering everything together, I raced upstairs to plug the board into my computer.  As these things go, instant success is rare, so I wasn't surprised when the programmer failed to detect the board.  After rooting around with a multimeter, I found the problem.  This is a problem I noticed the last time I printed the board, but somehow I failed to remedy it.  The reset pin was not connected to the programming header. A friend called this afternoon to chastise me for not simply shipping the design off to a board house to have a professional board made.  You will notice my temporary "reset" wire, connected to the programmer.  This would also be the reason I have not shipped the board out to manufacturer yet.  Once I finished the design I'll have several professional boards printed....

Read More »

When we last left our hero (yeah, that's me), he was about to try his luck with a second two layer board after his initial failure... I did.  And I failed.  Again.  The board still didn't etch cleanly the second time around, but it was better.  In fact, it was "good enough".  Using a very tiny screwdriver, I separated the many traces that did not etch properly.  That time consuming process was followed by a very careful testing process, so that I would know precisely how poorly the etching job was.  Finally, after lowering my expectations to simply being able to "talk" to the chip, I attached it to the board. This is a $17 chip, and etching a double sided, high density board is a pain in the rear.  You might imagine what I was saying to myself as I soldered the chip onto the board.  It was something to the effect of "Don't screw up.  Don't screw up.  Check your alignment.  Check your orientation." The programmer couldn't talk to the chip.  Nothing.  Nada.  I busted out the eye loupe and checked my solder...

Read More »