Generic Calculator Shield for Arduino Photo-journal

[MarkHaysHarris777]

Greetings, I have begun work on the actual analog keyboard and hope to be testing on both the Arduino and the Edison by the weekend, or early next week... The red-boards are still back-order from Sparkfun so I may have to punt and either make my own, or find another vendor who can deliver them.

I am also taking a look at the recommended LCD and keyboard scanner IC from Texas Instruments / that little guy might be promising at some point. But I'm getting ahead of myself somewhat because I need to become an expert at reflowing my own Hirose 70 pin connectors, without becoming a full lab. I've been talking to guys who have converted a toaster; one guy uses a fry pan... and Dave F on this site said that the convection oven will be just fine... (and I need a test bed... )

I have continued to test with the analog keyboard prototype (that thing is stable, solid, and error free). The worst I have been able to 'make' it do is to fail to register a keystroke when hit fast and also very close together; I'll put it this way... my HP35s and my WP34s both fail more frequently than the analog prototype board, under the same conditions! I'm beginning to think that the prototype board may actually be able to roll-over and buffer keystrokes (if that were necessary). The interrupt mechanism has not failed (since adding the 555 timer). ... since the time of the output pulse is not really critical I think I can get by with ceramic caps.

Cheers,
marcus