Supercon Badge Reads A “Punch” Card

Supercon Badge Reads A “Punch” Card

This year’s Hackaday Supercon, the 1st since 2019 many thanks to the pandemic, was a extremely related affair to all those of the previous. Pretty much every hardware-oriented hacker event has its individual personalized electronic badge, and Supercon was no various. This year’s badge is a simulation platform for a hypothetical 4-bit CPU developed by our own [Voja Antonic], and offered a true challenge for some of the attendees who had hardly ever touched device code through their formative many years. The obstacle set was to come up with the most exciting hack for the badge, so collaborators [Ben Hencke] and [Zach Fredin] established about nailing the ‘expandr’ class of the competition with their optical punched card reader bolt-on.

Peripheral connectivity is rather restricted. The plan was to construct a bolt-on board with its possess area processing — employing a PixelBlaze board [Ben] introduced along — to take care of all the scanning specifics. Then, when the software on the card was browse, dump the full matter above to the badge CPU through its serial interface. Devoid of obtain to theirPrinted paper faux punch card showing read LEDs and an array of set and reset bits of the encoding usual facilities again household, [Ben] and [Zach] clearly had to improvise with whichever they had with them, and no matter what could be scrounged off other badges or other components lying all around.

Just one massive difficulty was that most men and women never ordinarily carry photodiodes with them, but luckily they remembered that an LED can be employed as a photodiode when reverse-biased appropriately. Feeding the sign produced above a a person 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 among unfilled and stuffed test-bins on the loaded-in application playing cards.

The CPU needed 12-little bit opcodes, which obviously implies 12 photodiodes and 12 LEDs to browse each word. The PixelBlaze board does not have this several analog inputs. A uncomplicated trick was rather of acquiring discrete inputs, all 12 photodiodes had been wired in parallel and fed into a solitary input amplifier. To differentiate the various bits, the illumination LEDs alternatively were being charlieplexed, consequently offering the unique bits as a sequence of values into the ADC, for subsequent de-serialising. The demonstration movie reveals that it performs, with a software loaded from a card and kicked into operation manually. This sort of entertaining!

Punch playing cards usually have a gap by means of them and can be study mechanically, and are a fantastic way to configure testers like this interesting vacuum valve tester we protected a shorter whilst back again. at?v=37RK_2ZXmPU