Supercon Badge Reads A “Punch” Card

Supercon Badge Reads A “Punch” Card

This year’s Hackaday Supercon, the initial because 2019 many thanks to the pandemic, was a very identical affair to those of the earlier. Nearly every hardware-oriented hacker function has its have tailor made electronic badge, and Supercon was no diverse. This year’s badge is a simulation system for a hypothetical 4-little bit CPU established by our own [Voja Antonic], and offered a genuine challenge for some of the attendees who had hardly ever touched equipment code for the duration of their formative yrs. The problem established was to appear up with the most exciting hack for the badge, so collaborators [Ben Hencke] and [Zach Fredin] established about nailing the ‘expandr’ category of the competitors with their optical punched card reader bolt-on.

Peripheral connectivity is considerably confined. The concept was to construct a bolt-on board with its own community processing — using a PixelBlaze board [Ben] brought along — to handle all the scanning particulars. Then, the moment the program on the card was browse, dump the total detail about to the badge CPU by using its serial interface. Devoid of accessibility to theirPrinted paper faux punch card showing read LEDs and an array of set and reset bits of the encoding regular amenities back residence, [Ben] and [Zach] naturally experienced to improvise with whatever they had with them, and whichever could be scrounged off other badges or other components lying all-around.

Just one big concern was that most people don’t generally have photodiodes with them, but the good thing is they remembered that an LED can be utilized as a photodiode when reverse-biased correctly. Feeding the signal produced about a 1 Meg resistance, into a transconductance amplifier courtesy of a donated LM358 there was plenty of variation for the STM32 ADC to reliably detect the distinction between unfilled and crammed check-packing containers on the loaded-in program playing cards.

The CPU demanded 12-little bit opcodes, which of course implies 12 photodiodes and 12 LEDs to browse each and every phrase. The PixelBlaze board does not have this lots of analog inputs. A straightforward trick was as an alternative of having discrete inputs, all 12 photodiodes had been wired in parallel and fed into a single enter amplifier. To differentiate the unique bits, the illumination LEDs rather were being charlieplexed, thus delivering the unique bits as a sequence of values into the ADC, for subsequent de-serialising. The demonstration movie reveals that it will work, with a system loaded from a card and kicked into procedure manually. This kind of pleasurable!

Punch playing cards typically have a gap through them and can be read through mechanically, and are a wonderful way to configure testers like this intriguing vacuum valve tester we included a limited while back again.

https://www.youtube.com/look at?v=37RK_2ZXmPU

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