Pogo Pin Serial Adapter Thing

A few weeks ago, I was working on a small project of mine, and I faced a rather large problem. I had to program nearly five hundred badges in a week. I needed a small programming adapter that would allow me to stab a few pads on a badge with six pogo pins, press a button, and move onto the next badge.

While not true for all things in life, sometimes you need to trade quality for expediency. This is how I built a terrible but completely functional USB to serial adapter to program hundreds of badges in just a few hours.

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KeyMouSerial Solves Your Raspberry Pi Keyboard Problems

All laptops have a working keyboard and mouse built into them, the only problem is that you can’t use these tools on other computers that don’t have them. At least, until now. [Peter] has created the KeyMouSerial in order to use his laptop’s keyboard and mouse as physical devices on his Raspberry Pi, finally freeing the bonds holding our laptops’ human interface devices back.

The software for KeyMouSerial copies keystroke and mouse information and sends this out via a serial port on his laptop (using a USB to serial adapter). From there the information is translated by an Arduino into HID commands which are sent via USB to the target computer, in this case a Raspberry Pi. It’s a pretty elegant solution to carrying a bulky keyboard and mouse along just for a Raspberry Pi, or for any computer that might not have access to a network and SSH.

[Peter] has also been working on using his iPod as a serial-to-USB converter, so if you’re a Rockbox developer and want to help out then drop him a line. All of the software is available (for Windows, Mac, or Linux) including the Arduino sketch if you want to try this software out for yourself. And, if you don’t want to turn a computer into a keyboard and want to go the other direction and turn a keyboard into a computer, that is also an option.

Finding a Cheaper USB to Serial Chips

FTDI-gate wasn’t great for anybody, and now with hardware hobbyists and technological tinkerers moving away from the most popular USB to serial adapter, some other chip has to fill the void. The cheapest USB to serial chip on the market appears to be the CH340G, available for 20-40 cents apiece from the usual retailers. There is, however, almost no English documentation, and the datasheet for the CH340 family doesn’t include this chip. [Ian]’s here to help you out. He got his mitts on a few of these chips and managed to figure out the pinout and a few reference schematics. He even made an Eagle part for you. Isn’t that nice?

The CH340 series of chips do exactly what you would expect them to do: a full-speed USB device that emulates a standard serial interface, with speeds from 50bps to 2Mpbs. The chip supports 5V and 3.3V, and all the weird modem lines are supported. This chip even has an IrDA mode, because wireless communication in the 90s was exactly as rad as you remember.

With [Ian]’s help, we now have a cheap source of USB to serial chips. If you need the datasheet, here you go. The driver is a bit more difficult to find, but what you’re looking for is the CH341 family of chips. That can be found with a little bit of Google fu.

Kickstarter Monitor Will Brighten Your Day

Keeping up with a kickstarter campaign can be quite a task, especially if your project is real (looking at you, Scribble Pen!) and you’re trying to keep up with product fabrication and all the other logistics involved in bringing a product to market. [macetech] are currently in the middle of a campaign themselves and built a loud, bright alert system to notify them of any new kickstarter backers.

The project uses a LED marquee to display the current number of backers, but every time a new backer contributes to the project, a blindingly bright green arrow traffic signal is illuminated and a piezo speaker plays a celebration tune. All of these devices are controlled by an Arduino Yun which, with its built-in Atheros chipset, easily connects to the network and monitors the kickstarter page for changes.

[macetech] used some interesting hardware to get everything to work together. They used a USB-to-RS232 cable with and FTDI chip to drive the LED marquee and a PowerSwitchTail 2 from Adafruit to drive the power-hungry traffic signal. Everything was put together in a presentable way for their workshop and works great! All of the source code is available on their project page, and you can check out their RGB LED Shades kickstarter campaign too.

Antique Case for Custom File Server

Michigan Tech was throwing out a bunch of old electronic equipment, and [Evan] snagged quite a gem: a UHF signal generator built by Hewlett Packard circa 1955. He stripped all of the remaining electronics out of the case, but kept the slide-out trays and the front instrument panel to create this antique-looking file server.

The bottom tray was where the bulk of the electronics were housed, and since widespread adaptation of transistors for electronics wasn’t common at the time (the first silicon transistor wasn’t made until 1954), the original equipment was all vacuum tubes. This meant that there was just enough space for a motherboard, heat sink, and a couple of power supplies.

The hard drives are held in custom housings in the top portion of the case. The real magic, however, is with the front display panel. [Evan] was able to use the original meters, including a display for “megacycles” which is still technically accurate. The meters are driven by a USB-to-serial cable and a python script that runs on the server.

The antique case is a great touch for this robust file server. Make sure to put it in a prominent place, like next to your antique tube radio.

ARM Debugger for Nearly One Dollar

Oh that title is so misleading. But if you squint your eyes and scratch your noggin it’s almost true. Thanks to the hard work of [Peter Lawrence] it is now possible to hack together an extremely inexpensive CMSIS-DAP ARM debugger.

Let’s talk about function and we’ll get back to cost later. CMSIS-DAP is a standard that gives you the kind of breakpoint control you expect from a proper debugger. In this case [Peter] implemented the standard using 4k words of space on a PIC 16F1454. This lets it talk to the debug port on ARM chips, and the bootloader (also written by him) doubles as a USB-to-UART bridge. Boom, done. OpenOCD (and a couple of other software packages) talks to the PIC and it talks to the ARM. Nice.

Back to the cost question. You can get a 16F1454 for nearly a dollar when you order in quantity. If you cut up an old USB cable, recycle some jumper wire, and already have power and decoupling on hand, you’re in business for nearly one dollar.

USB to Serial adapter tells you what COM port you’re on


Since most of us are long past the days of hardware serial ports, the USB to serial adapter has become a mainstay on the hacker’s tool belt. While they’re cheap and convenient, USB to serial adapters aren’t always the easiest thing to use: there’s always the issue of what COM port Windows is calling your USB to serial adapter, or what TTY device it is in Linux/OS X.

[Avishay] has a very, very cool solution to this problem: put a display on a USB to serial converter to tell the user what COM port the OS labeled it as.

The prototype runs on a PIC  18F2553 dev board. When plugged into a Windows box, the serial adapter sets up two USB devices. The first device is a Communications Device Class that handles the grunt work of the USB to Serial connection. The second USB device is a proprietary piece of software that grabs the current COM port number. This number is displayed on an LCD thanks to a host application on the Windows PC that reports the COM port of the Serial adapter.

It’s one of those ideas where you didn’t know you needed it until it was presented to you. An excellent tool from [Avishay], although maybe a pair of 7-segment LEDs would make it a more manufacturable device.