Wednesday, July 25, 2012

Punch Card Reader - The Movie

Last year I bought an Arduino micro controller and spent some time building the experiments that came with the kit. Having rediscovered some old punch cards, I wondered if I could combine the Arduino, the CHDK firmware for Canon cameras, and my Linux desktop, and read in these old card decks. This is the result:


  1. So I'm a little confused as to how you're aggregating the cards info after you've read them. Can you explain a little about that?

  2. It's probably not that noticeable in the video - the card feeder is pulling cards off the bottom of the deck, so all I have to do is allow them to fall into a box of approximately the right size positioned such that the cards have to stack up. For example, given a deck of of A,B,C,D; the deck is being read from the bottom D,C,B,A and stacked into the box in that order which results in the original deck order of A, B, C, D. The fact that the deck is photographed backward can be corrected before putting the images through the python script, or afterwards by using the Unix rev command (I think I omitted that step in the video edit).