Broken RC Car Goes Online

When the remote for your son’s RC car goes missing, what are you going to do? Throw away a perfectly good robot chassis? No, we wouldn’t either. And these days, with WiFi-enabled microcontroller boards so readily available, it’s almost easier to network the thing than it would be to re-establish radio control. So that’s just what [Stian Søreng] did.

Naturally, there’s an ESP8266 board at the heart of this hack, a WeMos D1 to be specific. [Stian] had played with cheap remote-controlled cars enough to be already familiar with the pinout of the RC IC, so he could simply hook up some GPIOs from the WeMos board to the pins and the brain transplant was complete.

On the software side, he implemented control over TCP by sending the characters “F”, “B”, “L”, or “R” to send the car forward, back, left, or right. Lowercase versions of the same letters turns that function off. He then wrote some client software in Qt that sends the right letters. He says that response time is around 150-250 ms, but that it works for his driving style — crashing. (We’d work on that.)

Anyway, it’s a fun and fairly quick project, and it re-uses something that was destined for the junk heap anyway, so it’s a strict win. The next steps are fairly open. With computer control of the car, he could do anything. What would you do next?

Thanks [Eyewind] for the tip!

Monitor A Serial Port From Anywhere

This simple WiFi serial port monitor would have saved us a lot of trouble. We can’t count how many times where being hooked into an Arduino with USB just to get the serial out has nearly been more trouble than it’s worth. Times where we sat cross-legged on the floor and could choose comfort or accidentally shifting the set-up and ruining everything, but not both.

[Frenky]’s set-up is simple and clever. The Ardunio’s serial out is hooked to an ESP8266. The Arduino spams serial out to the ESP8266 in its usual way. The ESP8266 then pipes all that out to a simple JavaScript webpage. Connect to the ESP8266’s IP with any device in your house, and get a live stream of all the serial data. Neat.

As simple as this technique is, we can see ourselves making a neat little box with TX, RX, GND, and VCC screw terminals to free us from the nightmare of tethering on concrete floors just for a simple test. Video after the break.

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A Lucky Antenna

Antennas come in all shapes and sizes, and which one is best depends wholly on what you are doing with it. A very popular choice for sending video from drones is the cloverleaf antenna. It is circularly polarized which is an advantage when you have a moving vehicle. It also reduces multipath interference.

A cloverleaf contains three closed loops spaced at different angles. The antenna works well for transmitting but isn’t ideal for receiving. It is also difficult to tune after building it. However, for the right job, it is a good performer. [Vitalii Tereshchuk] shows how he made a cloverleaf antenna that fits a WiFi router.

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FCC Locks Down Router Firmware

For years, we have been graced with consumer electronics that run some form of Linux, have a serial port on the circuit board somewhere, and are able to be upgraded through official and unofficial means. That digital picture frame you got for Christmas in 2007 and forgot to regift in 2008? That’s a computer, and it would make a wonderful Twitter feed display. Your old Linksys WRT54G router? You can make a robotic lawnmower out of that thing. The ability to modify the firmware of consumer electronics is the cornerstone of Hackaday’s editorial prerogative. Now that right we have all enjoyed is in jeopardy, thanks to regulations from the FCC and laziness from router manufacturers.
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Passive WiFi On Microwatts

A lot of you use WiFi for your Internet of Things devices, but that pretty much rules out a battery-powered deployment because WiFi devices use a lot of juice. Until now. Researchers at the University of Washington have developed a passive WiFi implementation that uses only microwatts per device.

Working essentially like backscatter RFID tags do, each node has a WiFi antenna that can be switched to either reflect or absorb 2.4 GHz radiation. Your cell phone, or any other WiFi device, responds to this backscattered signal. All that’s missing is a nice steady signal to reflect.

passive_wifi-shot0008A single, plugged-in unit provides this carrier wave for multiple WiFi sensor nodes. And here’s the very clever part of the research: to keep the carrier from overwhelming the tiny modulated signal that’s coming from the devices, the plugged-in unit transmits off the desired frequency and the battery-powered units modulate that at just the right difference frequency so that the resulting (mixed) frequency is in the desired WiFi band.

If you’re a radio freak, you’ll recognize the WiFi node’s action being just like a frequency mixer. That’s what the researchers (slightly mysteriously) refer to as the splitting of the analog transmission stage from the digital. The plugged-in unit transmits the carrier, and the low-power nodes do the mixing. It’s like a traditional radio transmitter, but distributed. Very cool.

There’s a bunch more details to making this system work with consumer WiFi, as you’d imagine. The powered stations are responsible for insuring that there’s no collision, for instance. All of these details are very nicely explained in this paper (PDF). If you’re interested in doing something similar, you absolutely need to give it a read. This idea will surely work at lower frequencies, and we’re trying to think of a reason to use this distributed transmitter idea for our own purposes.

And in case you think that all of this RFID stuff is “not a hack”, we’ll remind you that (near-field) RFID tags have been made with just an ATtiny or with discrete logic chips. The remotely-powered backscatter idea expands the universe of applications.

Thanks [Ivan] for the tip!

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Giving WiFi To An Apple Newton

The Apple Newton gets a bad rap, partly because of the bad handwriting recognition of the first version of the firmware, and mostly because Steve Jobs hated it. Those who know of the Newton love the Newton; it has an exceptionally well-designed interface, the handwriting recognition is great with updated firmware.

[Jake] has the king of the Newtons – a MessagePad 2100. There’s a hidden port in this machine for a modem card, but Apple never made one. While other Newton aficionados trudge along with old PCMCIA WiFi cards that only support 802.11a without WPA2, [Jake] thought it would be possible to build a modern WiFi card for the Newton. He succeeded, opening the door to modern networking apps on the finest tablet Apple will ever make.

Oddly, this isn’t [Jake]’s first attempt at expanding the capabilities of his Newton. There’s an internal serial port inside the MessagePad 2×00, and a few years ago [Jake] tried to build an internal Bluetooth card. The RF design didn’t work, but with a few more years of experience, [Jake] figured he had the skills for the job.

The critical piece of hardware for this build isn’t an ESP8266 or other common WiFi module. Instead, a WiReach module from ConnectOne was used for the built-in PPP server. This allows legacy hardware to use standard AT modem commands to access a WiFi network. It’s a very interesting module; there is a lot of hardware out there that speaks PPP natively, and a module like this could be a drop-in replacement for a modem.

That said, thanks to unintelligible and ‘Apple Classified’ documentation, getting this card working wasn’t easy. The APIs to access the internal serial slot were never documented, and it took a bit of time with a disassembler to figure out how to address the port correctly.

[Jake] has pushed all the files for his project up to Github. This includes the design files for the PCB, the Newton software that enables WiFi, and a nifty 3D printed port cover that shows off the new wireless capabilities of Apple’s greatest tablet.

BBQ Thermometers Get Serious

You can write with a fifty cent disposable pen. Or you can write with a $350 Montblanc. The words are the same, but many people will tell you there is something different about the Montblanc. Maybe that’s how [armin] feels about meat thermometers. His version uses a Raspberry Pi and has a lengthy feature list:

  • 8 Channel data logging
  • Plotting
  • Webcam (USB or Raspicam)
  • Alarms via a local beeper, Web, WhatsApp, or e-mail
  • Temperature and fan control using a PID
  • LCD display

You can even use a Pi Zero for a light version. There’s plenty of information on Hackaday.io, although the full details are only in German for the moment. As you can see in the video below, this isn’t your dollar store meat thermometer.

Even though a disposable pen does the same job as a Montblanc, most of us would rather have a Montblanc (although Hackday would have to hand out some pretty steep raises before we start using the Meisterstück Solitaire Blue Hour Skeleton 149).

We might have done more with an ESP8266 and then done more work on the client, but we have to admit, this is one feature-packed thermometer. We’ve seen simpler ones that use Bluetooth before, along with some hacks of commercial units.

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