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Oct
13
Written by:
Gary Holbrook
10/13/2008 6:17 PM
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.
It took three tries to get this board printed properly. It took two tries to populate the board with the bare minimum number of components. Two times I had to improvise a reset wire. Finally, after working on this thing for two months, I was ready to plug it in and see if it would run for me.
After carefully attaching the board to the programmer, I gingerly plugged in the programmer's USB cable. My computer made the "USB Device Connected" noise, so I opened up the AVR Studio programming application. I gingerly pressed "read signature" and waited for the failure notice to pop up.
Instead, I got...a valid signature! I almost cried.
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