[tech] Vending Machine 3 Button & MIFARE Reader

[Mitchell Pomery]

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]