[Matthew “wrongbaud” Alt] is well known around these parts for his hardware hacking and reverse-engineering lessons, and today he’s bringing us a JTAG hacking primer that demoes some cool new hardware — the PiFEX (Pi Interface Explorer). Ever wondered about those testpoint arrays on mSATA and M.2 SSDs? This write-up lays bare the secrets of such an SSD, using a Pi 4, PiFEX, OpenOCD and a good few open-source tools for JTAG probing that you can easily use yourself.

The PiFEX hat gives you level-shifted bidirectional GPIO connectors for UART, SPI, I2C, JTAG, SWD and potentially way more, an OLED screen to show any debugging information you might need, and even a logic analyzer header so that you can check up on your reverse-engineering progress.

The suggested software workflow pulls no punches either, proposing ease-of-use features like USB-Ethernet gadget mode and Jupyter notebooks. [wrongbaud] shows us how to find JTAG among the dozen testpads left on the SSD, get the SSD single-stepping through code, and dump some of its memory space as a test. Full of tricks of the trade like reverse-engineering devices on a sheet of paper you can leave markings on, this write-up gives you a solid background in JTAG hacking, even if you only have a Pi and an old SSD.

So how can you get your hands on one? [wrongbaud] says the plan is to open source both the PiFEX hardware and software in the near future. Until until then, it looks like at least the hardware it wouldn’t be too hard to re-implement it yourself if you wanted to get the hang of reverse engineering with the Raspberry Pi.

[Matthew “wrongbaud” Alt] is a good friend of Hackaday community. He’s stopped by to host a reverse engineering Hack Chat, and ran a HackadayU class on Ghidra. His reverse-engineering journeys are always an informative read, from using arcade machines as a Linux hacking primer, to hacking a cryptocurrency wallet through glitching attacks.

A network-attached storage (NAS) device is a frequent peripheral in home and office networks alike, yet so often these devices come pre-installed with a proprietary OS which does not lend itself to customization. [Codedbearder] had just such a NAS, a Terramaster F2-221, which while it could be persuaded to run a different OS, couldn’t do so without an external USB hard drive. Their solution was elegant, to create a new backplane PCB which took the same space as the original but managed to shoehorn in a small PCI-E solid-state drive.

The backplane rests in a motherboard connector which resembles a PCI-E one but which carries a pair of SATA interfaces. Some investigation reveals it also had a pair of PCI-E lanes though, so after some detective work to identify the pinout there was the chance of using those. A new PCB was designed, cleverly fitting an M.2 SSD exactly in the space between two pieces of chassis, allowing the boot drive to be incorporated without annoying USB drives. The final version of the board looks for all the world as though it was meant to be there from the start, a truly well-done piece of work.

Of course, if off-the-shelf is too easy for you, you can always build your own NAS.