Hack Correlation

I got this coffee machine from work because it was a maintenance nightmare. I'll tear it down, do the analysis on how it works and detail on some design problems as well. It's going to be a rather long post with quite a lot of pictures. I've marked all the detected problems with an asterisk " * ", I'm sure some have been forgotten as this teardown was performed 6 months ago. (for troubleshooting see  https://hackcorrelation.blogspot.de/2017/02/automated-coffee-machine.html )

This is one of those projects that just takes forever to finish, I must've started this 6 months ago. This part will describe all the hardware and various techniques used to figure out which signal goes where. Why do this? It's an improvement on the original firmware and an exercise in consumer product design. My goals will be listed in the second part of this post.

In the previous post I touched upon the fact that simulating hardware input events was very slow and not really suited for fast, repeated actions. The second approach is based on MonkeyRunner, a free library included with the Android SDK. It is able to talk to the Android device using a Python-like language. Part 1:  http://hackcorellation.blogspot.de/2013/07/android-game-automation-part-1.html

I've gotten two DVR MPEG4 recorders for free because they were labeled as "unfixable". Both of them were diagnosed with "no video" or "video problems".  Ever since I've had them I had suspected the 2.5V supply to be at fault but had no oscilloscope nor variable PSU at hand, so they have been sitting in my drawer for a few months. It was a 10 minute job: - probe the 2.5V output and see it oscillating between 2.4 and 4.2V - probe the PAL/AV output and see the scope could not get a lock even though it looked almost ok - bypass the supply and feed 2.5V from a variable PSU - probe and do a quick run to see everything is stable. I wish I could do a burn test but my trusty variable PSU is a linear one, getting quite hot at this voltage drop.

I've been avoiding to do a write-up on this section for several reasons. First, I'm using the IDA disassembler which is pretty expensive and thus quite extensively pirated. Unfortunately there are no freely available tools that I know of that can perform this task. Second, I really suck at assembler and C so might not be the best person to do these analysis. I've used the freely available Thumb decompiler plugin which is able to translate assembly into readable code but only in about 30% of the cases. There's no substitute for knowledge, it seems. Part 1:  http://hackcorrelation.blogspot.de/2013/07/txtr-beagle-teardown-part-1.html Part 2:  http://hackcorrelation.blogspot.de/2013/07/txtr-beagle-part-two-software.html Part 3:  http://hackcorrelation.blogspot.de/2013/07/txtr-beagle-part-3-storage-and-transfer.html Part 4:  http://hackcorellation.blogspot.de/2013/07/txtr-beagle-card-parser.html Part 5:  http://hackcorrelation.blogspot.de/2013/07/txtr-b...

I started playing around with the SD card contents to see how I can parse it and verify the functionality. The result is a small Java program that is able to read the contents page by page and display it on a little panel. You can type the page number and press <Enter>, you can use arrow keys or mouse wheel to scroll.

Jack bottle to soap dispenser