[tech] Vending Machine 3 Button & MIFARE Reader

[mjpomery at ucc.asn.au]

Hi Mark,

As per my email last night, attached is a patch to fix the bug 
introduced with the fix to MIFARE card reading in the Vending Machine. 
The card reader won't read a card that isn't linked to an account when 
you log into the machine to enrol it, if it was the last card tried.

Hi Door,

The Important Bit (For Door members who skim this):
It also seems that there is an issue with reading some student cards. 
They are not picked up by the card reader at all (so it isn't even 
getting to my code changes). I haven't seen it personally, so if anyone 
sees this happening, can they make a note of who it was if I'm not 
around the clubroom, or grab me if I am there.

Regards,
Mitch Pomery
UCC President 2014


On 2015-03-04 00:00, Mitchell Pomery wrote:
> The Three Button:
> 
> As we all know, the vending machine's 3 button is the worst thing that 
> can
> ever happen to you. But worry no more, for I had an ingenious idea that
> worked!
> 
> What was the problem:
> The three button the the vending machine bounced, meaning it was not
> uncommon to get four 3's when you only wanted one. This was the state 
> it
> got two when I finally got fed up with it.
> 
> How I tried to fix it:
> I tried to impliment hardware debouncing, but found it largely
> unsuccessful due to the type of button and the inability to rewire it
> nicely.
> 
> What I ended up doing:
> Desoldering both the 3 and the reset keys, swapping the switches then
> soldering them back in.
> 
> What the end result was:
> I was expecting the reset key to bounce, but it did not. The three 
> button
> did not bounce either. I somehow managed to take a bouncy switch and a 
> non
> bouncy switch and create two non bouncy switches.
> 
> MIFARE Reader:
> 
> The new MIFARE reader is capable of reading cards much faster than the
> previous one was. This meant that people enrolling new cards would see
> "Card Already Enrolled" when they first held it up. This did confuse 
> some
> of the new members. Since then I have patched VendServer to only read 
> each
> card once. When you hold a card up to the reader, it will be read 
> multiple
> times, but the software will only act upon that card once. Using 
> another
> card or logging out of the machine is enough to get it read again.
> 
> And while typing this, I have thought of a potential bug: Holding a 
> card
> up that is not linked to an account. I will investigate this sometime
> tomorrow.
> 
> The Eternally Busy,
> Mitchell Pomery [BG3]
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