You’ll Flip for This 7404 IC Motherboard Fix

We often lament that the days of repairable electronics are long gone. It used to be you’d get schematics for a piece of gear, and you could just as easily crack it open and fix something as the local repairman — assuming you had the knowledge and tools. But today, everything is built to be thrown away when something goes wrong, and you might as well check at the end of a rainbow if you’re searching for a circuit diagram for a new piece of consumer electronics.

But [Robson] writes in with an interesting story that gives us hope that the “old ways” aren’t gone completely, though they’ve certainly changed for the 21st century. After blowing out his laptop’s USB ports when he connected a suspect circuit, he was desperate for a fix that would fit his student budget (in other words, nearly zero). Only problem was that he had no experience fixing computers. Oh, and it takes months for his online purchases to reach him in Brazil. Off to a rocky start.

His first bit of luck came with the discovery he could purchase schematics for his laptop online. Now, we can’t vouch for the site he used (it sure isn’t direct from Dell), but for under $5 USD [Robson] apparently got complete and accurate schematics that let him figure out what part was blown on the board without even having to open up the computer. All he had to do was order a replacement IC (SY6288DAAC), and solder it on. It took two months for the parts to arrive, and had to do it with an iron instead of a hot air station, but in the end, he got the part installed.

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Playing Doom on Keysight Oscilloscope via Windows CE

We all know the drill when buying a digital oscilloscope: buy the most hackable model. Some choose to void the warranty right away and access features for which the manufacturer has kindly provided all the hardware and software but has disabled through licensing. Few of us choose to tap into the underlying embedded OS, though, which seems a shame.

When [Jason Gin]’s scope started giving him hints about its true nature, he decided to find a way in. The result? An oscilloscope with a Windows desktop that plays Doom. The instrument is a Keysight DSOX1102G which [Jason] won during the company’s “Scope Month” giveaway. Relatively rare system crashes showed the familiar UI trappings of Windows CE.

Try as he might, [Jason] couldn’t get the scope to crash on cue — at least not until he tried leaving an external floppy drive plugged into the USB port on startup. But in order to use the desktop thus revealed, a keyboard and mouse were needed too. So he whipped up a custom USB switch cable, to rapidly toggle in the keyboard and mouse after the crash. This gave him the keys to the kingdom, but he still had a long way to go. We won’t spoil the story, but suffice it to say that it took [Jason] a year and a half, and he learned a lot along the way.

It was nice to hear that our review of the 1000X series scopes helped [Jason] accomplish this exploit. This hack’s great for bragging rights, as one way to prove you’ve owned a system is telling people it runs Doom!

Recovering Data From A Vintage MFM Drive

Even if you aren’t a vintage computer aficionado, you’re probably aware that older computer hard drives were massive and didn’t hold much data. Imagine a drive that weighs several pounds, and only holds 1/1000th of what today’s cheapest USB flash drives can. But what you might not realize is that if you go back long enough, the drives didn’t just have lower capacity, they utilized fundamentally different technology and relied on protocols which are today little more than historical footnotes.

A case in point is the circa 1984 Modified Frequency Modulation (MFM) drive which [Michał Słomkowski] was tasked with recovering some files from. You can’t just pop this beast into a USB enclosure; copying files from it required an interesting trip down computing’s memory lane, with a sprinkling of modern techniques that are sure to delight hackers who still like to dip their toes into the MS-DOS waters from time to time.

The drive, a MiniScribe 2012, has its own WD1002A-WX1 8-bit ISA controller card. [Michał] is the kind of guy who just so happens to have an ISA-compatible AT motherboard laying around, but he didn’t have the correct cooler for its Pentium processor. He stuck a random heatsink down onto it with a rubber band and set the clock speed as low as possible, which worked well enough to get him through the copying process.

Not wanting to fiddle with floppies, [Michał] then put together a setup which would let him PXE boot MS-DOS 6.22 under Arch Linux. He used PXELINUX, part of the syslinux package, and created an entry for DOS in the configuration file under the pxelinux.cfg directory. He then installed netboot which combines a DHCP and TFTP server into one simple package, and configured it for the MAC address of the AT machine’s 3com 3C905C-TXM network card.

With the hardware and operating system up and running, it was just a matter of getting the files off of the MFM drive and onto something a bit more contemporary. He tried to copy them to a secondary IDE drive, but it seemed there was some kind of conflict as both drives wouldn’t operate at the same time. So he pulled another solution from his bag of tricks: using a USB mass storage device on MS-DOS. By emulating a SCSI drive, he was able to get a standard flash drive plugged into a PCI USB card working, which ultimately dragged these ~35 year old files kicking and screaming into the 21st century.

We love keeping old hardware alive here at Hackaday, and documented methods to not only PXE boot DOS but use USB storage devices when you get it up and running will hopefully inspire some more hackers to blow the dust off that old 386 in the attic.

New Part Day: The Fifty Cent USB Chip

If you want to plug a USB cable into your next project, you’ve got a problem. USB is not UART, and UART is what every microcontroller serial port wants. To add USB to your microcontroller project, you’ll need to add a support chip, probably from FTDI, although there are a multitude of almost-FTDI clones available from the other parts of the Internet. These parts are slightly expensive, and they require some support circuitry. What you really need is a simple device that requires minimal external components, takes in serial from your microcontroller and spits out USB, and costs no more than a dollar. Bonus points if it’s hand-solderable.

The CH330 is apparently the answer to this problem (That’s a TaoBao link, this is probably going to be the best link going forward). It’s a dead simple chip with eight pins. Two are the data lines on a USB cable, and two are TX and RX for your microcontroller. The other pins are just power, ground, and an RTS line. Best of all, it only costs about fifty cents. You’ve never heard about it, because a few hours after this post is published, it will be the most information you’re going to get on this chip in the English-speaking world.

As far as we can tell, the CH330 is the smallest in a line of USB to UART converters from WCH, although the part isn’t even on the company’s website. The first reference to the phrase ‘CH330’ in reference to a USB chip appeared about a month ago, at the beginning of September. There’s a GitHub for someone who is apparently using this chip in a Pine64 board, but that’s about it. There’s no more information.

Right now, the only documentation for this chip is a single Chinese-language datasheet with an example schematic showing this chip connected to a MAX232 as a USB to RS232 converter. This is it. You’re looking at all the information that exists on this chip in the English-speaking version of the Internet.

The idea of a cheap, small chip that easily turns USB into UART would be great for thousands of projects. An FTDI chip will work, yes, but if you’re making thousands of a thing you might want to go with the fifty cent part over the two dollar part. That said, we’re in untested waters with this part, and you can’t even find it on AliExpress.

Let us know if you’ve gotten your hands on one of these devices. This has the potential to be really useful in a lot of projects and products, and we’re eager to see what the community comes up with. Thanks to [acabx] for sending this one in on the tip line.

Vampire Charger is a Rugged Anything-to-5VDC Converter

USB sockets providing 5 VDC are so ubiquitous as a power source that just about any piece of modern portable technology can use them to run or charge. USB power is so common, in fact, that it’s easy to take for granted. But in an emergency or in the wake of a disaster, a working cell phone or GPS can be a life saver and it would be wise not to count on the availability of a clean, reliable USB power supply.

That’s where the Vampire Charger by [Matteo Borri] and [Lisa Rein] comes in. It is a piece of hardware focused on turning just about any source or power one might possibly have access to into a reliable source of 5 VDC for anything that can plug in by USB. This is much more than a DC-DC converter with a wide input range; when they say it is made to accept just about anything as an input, they mean it. Found a working power source but don’t know what voltage it is? Don’t know which wire is positive and which is negative? Don’t even know whether it’s AC or DC? Just hook up the alligator clips and let the Vampire Charger figure it out; when the light is green, the power’s clean.

The Vampire Charger was recently selected to move on to the final round of The Hackaday Prize, netting $1000 cash in the process. The next challenge (which will have another twenty finalists receiving $1000 each) is the Human-Computer Interface challenge. All you need to enter is an idea and some documentation, so dust off that project that’s been waiting for an opportunity, because here it is.

Chromebook Trades Camera for WiFi Freedom

There are a number of companies now providing turn-key computers that meet the Free Software Foundation’s criteria for their “Respects Your Freedom” certification. This means, in a general sense, that the computer is guaranteed not to spy on you or otherwise do anything else you didn’t explicitly ask it to. Unfortunately these machines often have a hefty premium tacked on, making it an unpleasant decision between privacy and performance.

Freedom-loving hacker [SolidHal] writes in to tell us about his quest to create a FSF-compliant laptop without breaking the bank. Based on a cheap Asus C201 Chromebook, his custom machine checks off all the appropriate boxes. The operating system was easy enough with an install of Debian, and the bootloader was rid of any Intel Management Engine shenanigans with a healthy dose of Libreboot. But there was one problem: the permanently installed WiFi hardware that required proprietary firmware. To remedy the issue, he decided to install an internal USB Wi-Fi adapter that has the FSF seal of approval.

As the Chromebook obviously doesn’t have an internal USB port, this was easier said than done. But as [SolidHal] is not the kind of guy who would want his laptop taking pictures of him in the first place, he had the idea to take the internal USB connection used by the integrated webcam and use that. He pulled the webcam out, studied the wiring, and determined which wires corresponded to the normal USB pinout.

The FSF approved ThinkPenguin Wi-Fi adapter he chose is exceptionally small, so it was easy enough to tuck it inside some empty space inside of the Chromebook. [SolidHal] just needed to solder it to the old webcam connection, and wrap it up in Kapton tape to prevent any possible shorts. The signal probably isn’t great considering the antenna is stuck inside the machine with all the noisy components, but it’s a trade-off for having a fully free and open source driver. But as already established, sometimes these are the kind of tough choices you have to make when walking in the righteous footsteps of Saint Ignucius.

Internal laptop modifications like this one remind us of the Ye Olden Days of Hackaday, when Eee PC modifications were all the rage and we still ran black and white pictures “taped” to the screen. Ah, the memories.

USB Reverse Engineering: A Universal Guide

Every hacker knows what it is to venture down a rabbit hole. Whether it lasts an afternoon, a month, or decades, finding a new niche topic and exploring where it leads is a familiar experience for Hackaday readers.

[Glenn ‘devalias’ Grant] is a self-proclaimed regular rabbit hole diver and is conscious that, between forays into specific topics, short-term knowledge and state of mind can be lost. This time, whilst exploring reverse engineering USB devices, [Glenn] captured the best resources, information and tools – for his future self as well as others.

His guide is impressively comprehensive, and covers all the necessary areas in hardware and software. After formally defining a USB system, [Glenn] refers us to [LinuxVoice], for a nifty tutorial on writing a linux USB driver for an RC car, in Python. Moving on to hardware, a number of open-source and commercial options are discussed, including GoodFET, FaceDancer, and Daisho – an FPGA based monitoring tool for analysing USB 3.0, HDMI and Gigabit Ethernet. If you only need to sniff low speed USB, here’s a beautifully small packet snooper from last year’s Hackaday prize.

This is a guide which is well-informed, clearly structured, and includes TL;DR sections in the perfect places. It gives due credit to LibUSB and PyUSB, and even includes resources for USB over IP.

If you’re worried about USB hacks like BadUSB, perhaps you should checkout GoodUSB – a hardware firewall for USB devices.

Header image: Ed g2s (CC-SA 3.0).