Saturday, 20 April 2013

Beer fridge on the go

It's been a little while since my last post about the beer fridge so let's get you up to date. Since my last post:
1. My company has sponsored the fridge (so they'll pay for all the parts :-) )
2. We spent a Saturday getting to work on it.
3. It's not finished yet
4. I'm having issues with the MOSFEST/solenoid part

The basic design is as follows:
 A fridge will be locked from the inside by a set of solenoids acting as bar locks. The solenoids and the corresponding LEDs are controlled by an Arduino. The Arduino takes commands from a Raspberry Pi over serial and the Pi will have network connectivity.

 If you want to open the fridge, complete the fiendish hacking challenges on the Pi. Each challenge will control 1 or more solenoid. Unlocking the solenoid will only keep it unlocked for 30 seconds.

On the front of the fridge is a little black box. This has a set of red and green LEDs that will change whenever a lock is opened. There will also be (very importantly), a key lock that will bypass all challenges and power all the solenoids. This is because if (when) the pi or Adruino crashes, I still have a way to open the fridge. Otherwise it would be a matter of crowbar and damage.

fridge with the override lock
The next steps will be getting it in a working state. Currently there is only 1 solenoid (they are an absolute pain to mount correctly given the fridge's build and the small range of motion of the solenoid).

 I was thinking of having a Python script that sent the command over serial. The problems are that the exact serial port can change and also that writing to the serial port requires root permissions. I need to create a user to do this then Suid the python file (possible?).

 Finally it will be a matter of mounting it on the door. I'm a little worried that the condensation inside the fridge will screw with the electronics. Time will tell

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