Hack Correlation

This is just a reiteration of my post on  http://www.eevblog.com/forum/ . Since then some people have picked up the challenged and designed new firmware for the microcontroller. Let me explain. The module is a cheap (2-3$) 0-30V voltmeter. It has a 3-digit output, is pretty accurate and begs curiosity with it's TXD/RXD soldermask labels. The inside sports an STM800S3F3 chip with nice features: 2.95-5.5V supply voltage 16 Mhz internal oscillator 3 timers 4 CCP/PWM modules 5-channel 10-bit ADC UART, SPI, I2C 8k Flash, 1k RAM Thoughtfully, the programming/debug port is also broken out, just not labeled. The pinout would then be:   SWIM / PD1 (HS)   TX / AIN5(HS) / PD5   RX / AIN6 (HS) / PD6   NRST   VDD   VSS The board also includes a 3V/30mA linear regulator that can take up to 30V. All-in-all a very cheap development board that can be used for a lot of stuff Here's a close-up picture of the board under strong light ...

Update: if you came here looking for a fix to the annoying beep I might have one - if you are feeling handy: take the unit apart, desolder one wire from the battery terminal, discharge the capacitor (by touching the disconnected wire to the other wire) and solder it back on. Take care not to short the battery, you only want to discharge the circuit with the battery disconnected. If you do not understand perfectly what you need to do then please do not attempt this! This has 'fixed' one of my units (since 6 months) and has quitened another one for ~2 months. Back to the original post: On of the my smoke detectors - installed by the landlord under legal obligation - started acting up by emitting annoying short beeps and random intervals, moreso during the night. The producer boasts a 10-year service lifetime, smoke detection as well as heat detection. Since they are the "non-user-serviceable" type nothing else remains than to take it apart and see wha...

I'm working on a small project in which I'm trying to find out if I can output a sound on a piezo while reading the force exerted on it. It's like a small piano where the input is also the output. I did something similar with LEDs where I measured the light level by first reverse polarising the led and then measuring the discharge time (capacitance). To have an idea with what levels I'm dealing some measurements were in order. Two sets of measurements were taken, one with the original molded plastic housing and one with the housing removed and two wires solder to the piezo. I'm using a normal buzzer, the cheapest I could find, so that I can buy several of them. Raw buzzers should be 10x cheaper than what I paid. This is a light tap on the table while the sensor is sitting about 1m away pressed against the table. The housing was on. Around 1Nm of force from a lighter. A stronger tap under the same conditions, around 5Nm. The same stronger tap...

This project is taking longer than anticipated even though it was supposed to be something simple. I will publish a schematic of the complete circuit in the near future (this year) but in the meantime there is still the slow process of troubleshooting. Safety considerations: the complete circuit is not isolated from mains so testing is pretty critical. I have been feeding 3.6V to test the low-voltage part but in the end it will have to be hooked up to 220V the boiler / water heater can only take a limited amount of pressure. If the thermistor is not properly calibrated in software there is the risk of a scalding hot water explosion With that being said there is some small but steady progress being done. The MSP430 has a some strange power requirements that are not properly documented. The VCC supply  needs to rise with >1V/ms otherwise it gets into an undefined state. That undefined state might also mean that some GPIOs are high, causing catastrophical failure. C...

My TV has a quite complex set of features, none of which work particularly well. Except perhaps using it as a PC display. Input latency is quite bad, ranging from over 200ms in normal mode to 100ms in "gaming" mode. The latency can easily be tested by going to this link and making a picture of both displays (native and external) at the same time, preferably with a flash, in order to shorten exposure time. There's a half-assed [HBBTV] implementation that crashes once in a while, a horrible YouTube app that takes 1-2 seconds to react to keypresses, a barely-workable DLNA implementation and barely-acceptable USB media integration. Oh, it also does triple-tuner TV, but I don't watch TV. Sometimes I'm just wishing they would have stuck with a Linux, WinCE or Android implementation with freeware apps instead of reinventing the square wheel each time. What's worse, each of these apps (TV, DLNA, HBBTV, YouTube, USB media) seems to be written by a diff...

Zoom G1 I got this unit essentially for free a few years back after getting rid of my VooDu Valve which was too expensive/overkill. It's a nice little unit great for practicing guitar and has the added bonus of foot switches (the two big knobs at the bottom): This unit has seen better days and it kept switching itself off or resetting once in a while whenever the cables were moved. Also, it didn't want to work on battery power.

In the first part I identified the problem leading to the unit overheat: a design decision consisting of dropping more than 10 Watts on a couple of 3W resistors. I've thought of several ways to address the issue: change the 5V rail to a switching design put bigger resistors and mount the 7805 on a heatsink have a switching or linear preregulator that drops 12V to a more manageable 7-9 Volts I have a few switching supplies bought from ebay at around 2-4$ each based on the LM2596 reference design. However they might be noisy and I'm not sure how well they handle high loads. Should be good enough for charging the USB and anyway the 1.8V and 3.3V lines go through linear regulators first, cleaning them of noise. The bigger resistor solution would also work but I did not have any 10W resistors at hand and I'm not sure they would fit in the small space between the CD tray and the case. Since I have a few LM7808 and LM7809 from scrap I decided to go with the third solut...

I've bought a somewhat cheap car MP3 player a few years ago on the reason that it had Bluetooth support and nice amber lights to complement the design of my E39. I understand some people will come here looking for a wiring diagram so I should start with that first: Model: Watson CRC8060MU I've always had the issue of not being able to charge anything from the USB port or the unit resetting with some strange USB sticks. Also, the unit lost its settings when cranking the engine with a low battery while it was playing music. After the jump I start taking it apart to see how it works and what can be done to address the issues.

I wanted to see the limits of the current method so I set out hunting a board template for that.

Completed prototype board For today I've planned some easy-reading and low-tech tutorial. The bane of a lot of software guys is moving up from the ubiquitous breadboard to a self-made PCB. The other common fear is switching from through-hole parts to surface-mount technology.

I was scoping around to see what caused the 2.5V supply modules to go bust. Just as a reminder, they are pretty generic modules, with a 5V preregulator that steps down the 12V input. The 5V is then dropped through linear regulators to three supply rails of 1.8V, 2.5V and 3.3V. In this application only the 2.5V output is being used.

I just bought a cheap broken DVR from eBay and thought to share pictures from inside the unit since there aren't any on the Internet. It was a state of the art unit at the beginning of 2000, probably costing several thousands of dollars. Some documents and review from that time praise the wavelet-type encoding quality and savings, custom-made ATX power supply and build quality. I beg to differ on a few fronts.

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

This experiment was done about a year ago so I don't have all the details at hand. I wanted to see if a car USB charger can be modified to run on 1-3V. The car charger is based MC34063 chip which can function in both buck and boost configurations.

I've had a car charger break down on me and haven't been able to fix it. It has a sturdy metallic case and the transformer is still fine. The idea is to use some existing PSU modules I have laying around and fit those into the case, providing a readout on the display. Since it has to have a microcontroller (overpowered if I might add) it can also do some basic logging, over-voltage and over-current protection. I really hate designing my own supplies since there are so many ready-made around which are much better than I could ever accomplish.

I'm wrapping this up for now as one of the COG (chip-on-glass) devices has apparently fried and the reader has sold out. UPDATE : Andreas Schier has written an open-source java toolchain for Beagle:  https://github.com/schierla/jbeagle UPDATE : Florian Echtler has built two Python scripts, one emulating the server and another one for the client. The server allows you to send images to your reader:  http://floe.butterbrot.org/matrix/hacking/txtr/ Part 1:  http://hackcorrelation.blogspot.com/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-beagle-native-code-analysis.html I've scratched some of the white glue-like ...

Bluetooth Thanks to Moritz I was able to connect to txtr via the Bluetooth SPP profile. To do this you need to disable the txtr app that is installed on your phone and install any app that does Bluetooth serial debugging. I used "Bluetooth SPP", available freely on the Play Store. UPDATE : Andreas Schier has written an open-source java toolchain for Beagle:  https://github.com/schierla/jbeagle My own version:  https://github.com/ligius-/jbeagle UPDATE : Florian Echtler has built two Python scripts, one emulating the server and another one for the client. The server allows you to send images to your reader: http://floe.butterbrot.org/matrix/hacking/txtr/ 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://hack...

In a previous posting I described how I got this iPod Classic 6G working again by just using an older 1.8" drive. I did not provide any pictures, so here are two of them with the "roadkill".

First: this is borderline immoral so don't ask for any source code or help. My friend got me into a repetitive Android game that I will not name here. Basically it's a different kind of Farmville (I assume) that requires you to mindlessly click 'animals' to 'farm' money from them. On top of that you have to also activate two type of farms in order to feed the animals and evolve them. Feeding is not a requirement, so it will only be done in the second iteration of this automation. As a rule of thumb any task that takes you at least 5 minutes every day for a year should be automated if it could be done in less than 20 hours.

As you might now the txtr Beagle is the new kid on the block: the cheapest and lightest ebook reader around. Or at least that's what the marketing says. I bought mine for around 20E, which is quite a bit more than the 10-13 EUR they were aiming for. I guess that's the price one must pay to stay on top of technology. The main reason I bought one was to have some kind of remote display for use for example as a wall clock, To-Do board or bike GPS readout. Video: http://youtu.be/KTEGRSdxxxg 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-beagle-native-code-analysis.html It's a bit hard to take ap...

After a few hours of hunting templates I've finally settled on one that should be easy on the eyes. Just a matter of preference. This is not the final choice but until I learn the WordPress system it will have to do. I have about 20 articles waiting to be written, all the pictures are already taken, but I don't know where to start: - custom dual power supply with Stellaris (Tiva) Launchpad diagnostics - marathon repair of 30+ out-of-factory items - custom firmware for coffee machine - lessons learned from reviving SLA, NiCd and LiPo batteries - various laptop repairs - workbench build log - automating a native game on Android - sending Android navigation instructions to a Bluetooth device - reverse engineering Java and Android apps (one at a time) On top of that there are a lot of smaller articles in the loop, basically tips, mostly useful for beginners (diskless/thin clients, workbench organization, protocol debugging, Android development, teardowns etc.). I...