The Samsung PS-WTX500 subwoofer is designed to be used as part of a 5.1 channel home theater system, but not just any system. It contains the amplifiers for all the channels, but they’ll only function when the subwoofer is connected to the matching receiver. [Alejandro Zarate] figured there must be some way to unlock the system’s full functionality without being limited to the original receiver, he just needed to reverse engineer how the subwoofer worked.
The result is a fantastically well documented write-up that covers the whole process, starting with how [Alejandro] identified and researched the Pulsus PS9829B Digital Audio Processor (DAP). Documentation for this particular chip seems hard to come by, but he was able to find a similar chip from the same manufacturer that was close enough to put him on the right track. From there, he started studying the SPI communications between the DAP and the subwoofer’s S3P70F4 microcontroller.
After analyzing the communication between the two chips, [Alejandro] pulled the S3P70F4 off the board and wired an Arduino Pro Mini 328 in its place. The Arduino was quite a bit larger than the original microcontroller, but with some careful wiring, he manged a very professional looking installation. Short of coming up with a custom PCB adapter, we don’t think it could look much better.
With some relatively straightforward code and a listing of the captured byte sequences, the Arduino was able to power up the PS-WTX500’s amplifiers and handle the incoming audio signal as a stand-alone device.
We’d wager most hackers are familiar with FTDI as the manufacturer of the gold standard USB-UART interfaces. Before parts like the ultra cheap CH340 and CP2102 became common, if you needed to turn a USB cable into a TTL UART device, “an FTDI” (probably an FT232RL) was the way to make that happen. But some of the parts in the FT232* family are capable of much more. Wanting to get at more than a UART, [linker3000] designed the Shukran to unlock the full potential of the FT232H.
The FT232H is interesting because it’s an exceptionally general purpose interface device. Depending on configuration it can turn USB into UART, JTAG, SPI, I2C, and GPIO. Want to prototype the driver for a new sensor? Why bother flashing your Teensy when you can drive it directly from the development machine with an FT232H and the appropriate libraries?
The Shukran is actually a breakout for the “CJMCU FT232H” module available from many fine internet retailers. This board is a breakout that exposes a USB-A connecter on one side and standard 0.1″ headers on the other, with a QFN FT232H and all the passives in the middle. But bare 0.1″ headers (in a square!) require either further breadboarding or a nest of jumper wires to be useful. Enter the Shukran. In this arrangement, the CJMCU board is cheap and handles the SMT components, and the Shukran is easy to assemble and makes it simple to use.
The Shukran gives you LEDs, buttons and switches, and a bunch of pull up resistors (for instance, for I2C) on nicely grouped and labeled headers. But most importantly it provides a fused power supply. Ever killed the USB controller in your computer because you forgot to inline a sacrificial USB hub? This fuse should take care of that risk. If you’re interested in building one of these handy tools, sources and detailed BOM as well as usage instructions are available in the GitHub repo linked at the top.
You’ve probably seen a few of these miniature arcade games online or in big box retailers: for $20 USD or so you get scaled-down version of a classic arcade cabinet, perfect for a desk toy or to throw up on a shelf as part of your gaming collection. Like any good Hackaday reader, you were probably curious about what makes them tick. Thanks to [wrongbaud], we don’t have to wonder anymore.
Over the course of several blog posts, [wrongbaud] walks readers through the hardware and software used in a few of these miniature games. For example, the Rampage cabinet is using a so-called “NES on a Chip” along with a SPI flash chip to hold the ROM, while Mortal Kombat is using a Genesis emulation solution and parallel flash. It wouldn’t be interesting if they didn’t throw you a few curves now and again, right?
But these are more than simple teardowns. Once [wrongbaud] gives an overview of the hardware, the next step is reading the respective flash storage and trying to make sense of the dumped data. These sort of games generally reuse the hardware among a number of titles, so by isolating where the game ROM is and replacing it, they can be made to play other games without hardware modification. Here, this capability is demonstrated by replacing the ROM data for Rampage with Yoshi’s Cookie. Naturally it’s one of those things that’s easier said than done, but it’s an interesting proof of concept.
The Mortal Kombat cabinet is a newer addition to the collection, so [wrongbaud] hasn’t progressed quite as far with that one. The parallel flash chip has been dumped with the help of an ESP32 and a MCP23017 I/O expander, and some Genesis ROM headers are identifiable in the data, but there’s still some sifting to be done before the firmware structure can be fully understood.
Even if you’re not in the market for a diminutive arcade experience, the information that [wrongbaud] has collected here is really phenomenal. From understanding protocols such as I2C and SPI to navigating firmware dumps with a hex editor, these posts are an invaluable resource for anyone looking to get started with reverse engineering.
Writing image data to serially connected (SPI/I2C) displays from a microcontroller is easy enough these days, courtesy of standards defined by the MIPI Alliance, yet there are some gotchas in it which may catch someone using it unaware. [Larry Bank] wrote up a good summary of how one can get maximum performance out of such a display link.
At the core is the distinction between pixel data and command transmissions. The change from command to pixel data mode requires signaling, which takes precious clock cycles away from transferring pixel data between the MCU and display. The common MIPI DCS instruction set allows for a big reduction in needed data transfers by allowing parts of the display to be addressed instead of requiring a full refresh. Yet by not properly segmenting command and data transfers, one ends up unnecessarily slowing down the process.
The result is that one can run something like a Pac-Man emulator on an AVR MCU with a sluggish 320×480 SPI LCD at 60 FPS, as one can see in the video that is embedded after the break. Check the article for another demo video as well.
By now most of us have used a Raspberry Pi at some level or another. As a headless server it’s a great tool because of its price point, and as an interface to the outside world the GPIO pins are incredibly easy to access with a simple Python script. For anyone looking for guidance on using this device at a higher level, though, [Arun] recently created a how-to for using some of the Pi’s available communications protocols.
Intended to be a do-everything “poor man’s hardware hacking tool” as [Arun] claims, his instruction manual details all the ways that a Raspberry Pi can communicate with other devices using SPI and I2C, two of the most common methods of interacting with other hardware beyond simple relays. If you need to go deeper, the Pi can also be used as a full JTAG interface or SWD programmer for ARM chips. Naturally, UART serial is baked in. What more do you need?
As either a tool to keep in your toolbox for all the times you need to communicate with various pieces of hardware, or as a primer for understanding more intricate ways of using a Raspberry Pi to communicate with things like sensors or other computers, this is a great write-up. We also have more information about SPI if you’re curious as to how the protocol works.
Elliot Williams and Mike Szczys look at all that’s happening in hackerdom. This week we dive deep into super-accurate clock chips, SPI and microcontroller trickery, a new (and cheap) part on the microcontroller block, touch-sensitive cloth, and taking a home X-ray to the third dimension. We’re saying our goodbyes to the magnificent A380, looking with skepticism on the V2V tech known as DSRC, and also trying to predict weather with automotive data. And finally, what’s the deal with that growing problem of electronic waste?
Links for all discussed on the show are found below. As always, join in the comments below as we’ll be watching those as we work on next week’s episode!
Everyone loves NeoPixels. Individually addressable RGB LEDs at a low price. Just attach an Arduino, load the demo code, and enjoy your blinking lights.
But it turns out that demo code isn’t very efficient. [Ben Heck] practically did a spit take when he discovered that the ESP32 sample code for NeoPixels used a uint32 to store each bit of data. This meant 96 bytes of RAM were required for each LED. With 4k of RAM, you can control 42 LEDs. That’s the same amount of RAM that the Apollo Guidance Computer needed to get to the moon!
[Ben]’s solution uses some external hardware to reduce software requirements. The 74HC123 dual multi-vibrator is used to generate the two pulse lengths needed for the NeoPixels. The timing for each multi-vibrator is set by an external resistor and capacitor, which are chosen to meet the NeoPixel timing specifications.
The 74HC123s are clocked by the SPI clock signal, and the SPI data is fed into an AND gate with the long pulse. (In NeoPixel terms, a long pulse is a logical 1.) When the SPI data is 1, the long pulse is passed through to the NeoPixels. Otherwise, only the short pulse is passed through.
This solution only requires a 74HC123, an AND gate, and an OR gate. The total cost is well under a dollar. Anyone looking to drive NeoPixels with a resource-constrained microcontroller might want to give this design a try. It also serves as a reminder that some problems are better solved in hardware instead of software.