Rebuilding a Digital Safe

 

I got a Mossberg digital hotel safe from work after it failed to function and we had to find a more creative way to open it.  From what I could see everything seemed to function alright so I assume the failure was one of the integrated circuits.  Regardless, I’ve decided that I want to rebuild it using an arduino.  The control board features a 16X2 LCD display and a 3X4 matrix keyboard.  Both of these should be fairly easy to get to work since there are arduino libraries available for them.  I just need to figure out how the hell to use the libraries.  That, and the little task of determining the pinouts on the LCD.

I downloaded the datasheet for the Hitachi HD44780A00 and then I used a continuity tester to find what pins went where.

 

The pinout seems to be pretty straight forward.  I will probably use a 4-bit LCD library due to the fact that the arduino has only 14 digital Input/Output and there simply wouldn’t be enough pins for an 8-bit configuration plus a 3X4 matrix keyboard, and the two limit switches and motor that are used to lock the safe. 

The keypad itself was pretty simple to determine it’s pinout as all of the traces on the circuit board are easy to trace by eye.  It turns out that the top three pins are for the rows, from top to bottom, and the remaining four are the columns, from right to left.

Test of Windows Live Writer

Testing…

I saw a post on lifehacker.com about Windows Live Writer, so I decided to give it a try.  So far it seems to be easier to use than the Blogger interface which can be tedious and buggy.  For a free service Blogger is excellent, but if there is a way to improve it then I may as well try. 

Verdict:

The interface responds pretty quickly and there are some pretty nifty ways to manipulate photos such as the rounded corners on the pictures above.  The first time that I posted the text and picture above the text was nearly obscured by the photo.  It was simple to adjust the margins to fix that so overall I’d say that I’m pretty happy with it, in spite of it being a Microsoft product.

Dubbel Track Kegged

I finally got around to kegging the Dubbel Track Ale this weekend. The original gravity was around 1.065 according to the Northern Brewer website from which I bought the ingredient kit. I'm not sure if it came out to be exactly that as my hydrometer was broken when I brewed the beer, so I'll have to trust Northern Brewer. I purchased a new hydrometer and measured the final gravity to be 1.011. Using the instruction that came with the the hydrometer this indicates that the alcohol content to be approximately 7-7.5% by volume. Using the formula ABV = (OG -FG)*131 that I found on the Beeradvocate.com I narrowed it down to 7.074%. I hope that this doesn't indicate that the beer didn't fully ferment because the ABV was supposed to be around 7.5%. I tasted it after I kegged it and it was pretty good, so I guess that it all that really matters.

Really Bare Bones Board Build

I purchased an RBBB(Really Bare Bones Board) from Modern Device Company quite some time ago and I never quite got it to work right. The RBBB is a VERY minimalist version of the Arduino which is easy to put on a solderless breadboard. The kit cost $7 but you have to solder it together, including some very small components, so it can be chalenging if you are new to soldering, and damn near impossible if you have a crappy Radio Shack soldering iron. I had purchased a $150 Weller iron prior to the build, so I had nothing but inexperiance and lack of skill to blame for my troubles.

I actually managed to get the more difficult components soldered on without a problem but I somehow managed to overheat one of the pads on the pcb and I lost a connection to ground because of that. The board would work it was positioned just right such that the pad made contact, but it failed more often than not.

Tonight while working on the Xbees I decided that I should finally get around to fixing this so I came up with a rather inelligant, yet effective solution. While it is difficult to see in the photo, The pin that has the bad connection is the ground pin that I soldered the Pin 13 LED to. I must have spent too much time heating that pad up because I was trying to mount the LED to it. Regardless, my rather hoaky fix was to solder a wire onto the to of that pin and stuff the other end of that wire into the DIP socket of the corresponding AVR pin. I checked the continuity with my multimeter and lo and behold it worked without needing me to wiggle the pin until it could chance upon a connection. I proceeded to check the rest of the leads and found them all to be working, so perhaps I'll actually get to use the RBBB for a project sometime in the future.

Xbee Communication Part 1: Getting Started

I have spent my free time in the past few days playing with Xbee wireless modules. I move at a snail's pace because I'm terrible at managing my time effectively. I did manage to get the two modules to communicate. Not bad for like three intermittent hours of work. I spent a few celebratory minutes typing messages between the two before I decided to start making dinner.

The first step to working with the Xbees, aside from ordering the parts from Sparkfun.com, was to solder the breakout boards and wire the circuits up on breadboards. I managed to miss the recommendation that you purchase the 2mm sockets with the breakout board so that you can change the Xbee modules at a later date so I ended up soldering them directly to the breakout boards.

I also purchase a logic level converter from Sparkfun in order to step down the voltage of the serial data lines from the arduino to the Xbee from 5V to 3.3V. I had to solder header pins on this as well, but the SMD chips were already on the PCB so I didn't have to do the painstaking work of soldering those tiny things on myself.

I ran into a few problems getting the Xbees to respond to my serial commands. The first problem was that I seemed to have the TX and RX lines reversed. I could have sworn that they we wired as the diagram in Making Things Talk showed, but my mind often wanders from the page to the breadboard, so I could have been wrong. The second problem was just the fact that I had multiple serial terminals open at the same time. This resulted in some error messages or the terminals simply not responding at all. Personally, I prefer the error message, even if I didn't bother reading it.

I chatted with Lee about the problem at work and he told me about the conflict with multiple serial terminals and I was able to fix the problem as soon as I knew to only do one at a time. Now that I have the two talking I need to figure out a project where they might be useful. I'm sure that I'll think of something eventually. At least I've taken the first baby steps though.