RC Drag Racing Christmas Tree and Speed Trap

In the drag racing world, a Christmas tree is the post at the start line that sequentially lights up a set of yellow lights followed shortly after by a green light to tell the drivers to go, the lights obviously giving it its seasonal name. Included at the base of the tree are lasers to detect the presence of the cars.

[Mike] not only made his own Christmas tree for his RC cars, but he even made an end-of-track circuit with LED displays telling the cars how long they took. Both start and finish hardware are controlled by Pololu Wixel boards which has TI CC2511F32 microcontrollers with built-in 2.4 GHz radios for wireless communications.

In addition to the LEDs, the Christmas tree has a laser beam using a 650nm red laser diode for each car at the start line that’s aimed at a TEPT5600 phototransistor. If a car crosses its beam before the green light then a red light signals the car’s disqualification.

The end-of-track circuit has 7-segment displays for each car’s time. [Mike] designed the system so that the Christmas tree’s microcontroller tells the end-of-track circuit’s microcontroller when to reset the times, start the times, and clear the times should there be a disqualification. The finish line controller has lasers and phototransistors just like the starting line to stop the timers.

Oh, and did we mention that he also included 1980’s car racing game sounds? To see and hear it all in action check out the video after the break. If the cars seem a little drunk it’s because pushing left or right on the controller turns the wheel’s fully left or right.

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Drone Flies 12 cm on Wireless Power

[Sam M] wrote in with a quick proof-of-concept demo that blows our socks off: transferring enough power wirelessly to make a small quadcopter take flight. Wireless power transfer over any real distance still seems like magic to us. Check out the videos embedded below and you’ll see what we mean.

What’s noteworthy about this demo is that neither the transmitter nor the receiver are particularly difficult to make. The transmitting loop is etched into a PCB, and the receiver is made of copper foil tape. Going to a higher frequency facilitates this; [Sam M] is using 13.56 MHz instead of the kilohertz that most power-transfer projects use. This means that all the parts can be smaller and lighter, which is obviously important on a miniature quadrotor.

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Hacking a Dollar Store Bluetooth Device

Hardware hackers are always looking for devices to tear apart and scavenge from. It’s hardly a secret that purchasing components individually is significantly more expensive than the minuscule cost per unit that goes along with mass manufacturing. Bluetooth devices are no exception. Sure, they’re not exactly a luxury purchase anymore, but they’re still not dirt cheap either.

Luckily for [Troy Denton], it seems dollar stores have started carrying a Bluetooth camera shutter for just a few dollars (it was three bucks, perhaps the dollar store actually means divisible-by). The device is designed to pair with a smart phone, and has two buttons allowing you to control the camera from afar. The fact that it works at all at that price is a small miracle, but the device also has potential for hacking that adds to its appeal. Continue reading “Hacking a Dollar Store Bluetooth Device”

Raspberry Pi Walkie Talkie Mumbles To Friends

His kids wanted walkie talkies, so [Daniel Chote] built one. The TalkiePi is a neat project built around a Raspberry Pi running Mumble, the open-source voice chat system that his kids can share with their siblings and friends.

It’s easy enough to choose the Raspberry Pi, and Mumble is pretty well known. But what’s the easiest way you can think of to add microphone and speakers to the RPi? We applaud [Daniel’s] choice to equip it with the guts of a USB speakerphone. Mumble lets you choose voice activation or keyboard input — in this case an added button makes it push-to-talk, as you would expect in a traditional walkie talkie.

He put all of this into a nicely designed 3D case with a few LEDs, so it is easy to tell that it is ready to transmit. [Daniel] isn’t quite finished yet, though: he’s now working on a new version that is portable, battery powered and uses a Raspberry Pi Zero for the ultimate walkie talkie. We can’t wait to see someone take this to the extreme and include a cellular-modem. But then again, anywhere you can get on WiFi this rig should work, it’s not relegated to a single LAN, and that already far outperforms walkie talkies of yore.

Run a RepRap on an ESP8266

What can’t the little $5 WiFi module do? Now that [lhartmann] has got an ESP8266 controlling the motors of a 3D printer, that’s one more item to check off the list.

What’s coolest about this project is the way that [lhartmann] does it. The tiny ESP8266 has nowhere near the required number of GPIO pins, the primary SPI is connected to the onboard flash memory, and the secondary SPI is poorly documented and almost nobody uses it. So, [lhartmann] chose to use the I2S outputs.

I2S is most often an audio protocol, so this might at first seem like a strange choice. Although I2S sounds like I2C, it’s really essentially an SPI protocol with a fourth wire that alternates to designate the right or left channel. It’s actually just perfect for sending 16×2 bits of data at high data rates.

[lhartmann] takes these 32 bits and feeds them into four shift registers, producing 32 outputs from just the four I2S data lines. That’s more than enough signals to run the stepper motors. And since it updates at 192 kHz sample rate, it’s plenty fast enough to drive them.

The other side benefit of this technique is that it can work on single-board computers with just a little bit of software. Programming very complicated stepper movements then becomes just a matter of generating the right “audio” file and playing it out. [lhartmann] demonstrated this earlier with an Orange Pi. That’s pretty cool, too.

The code for turning the ESP8266 and a short handful of 74HC595s into a 3D printer controller are up on GitHub, so go check it out.

Thanks [CNLohr] for the tip!

Software USB On the ESP8266

A while back, [cnlohr] needed a USB keyboard and mouse. His box ‘o junk didn’t hold this particular treasure, and instead of hopping on Amazon like a normal geek or venturing into the outside realm on a mid-level ‘store’ quest like a normal person, [cnlohr] decided to turn an ESP8266 into a USB keyboard and mouse. How hard could it be? The ESP doesn’t support USB, but bitbanging hasn’t stopped him before. The end result is a USB stack running on the ESP8266 WiFI module.

[cnlohr] has been working for about a month on this USB implementation for the ESP, beginning with a logic analyzer, Wireshark, Xtensa assembly, and a lot of iteration. The end result of this hardware hacking is a board based on the ESP8285 – an 8286 with integrated Flash – that fits snugly inside a USB socket.

This tiny board emulates low-speed USB (1.5 Mbps), and isn’t really fast enough for storage, serial, or any of the fancier things USB does, but it is good enough for a keyboard and mouse. Right now, [cnlohr]’s ESP USB device is hosting a webpage, and by loading this webpage on his phone, he has a virtual keyboard and mouse on a handheld touchscreen.

If you’re keeping track, [cnlohr] has now brought Ethernet and USB to a tiny microcontroller that can be bought for a few bucks through the usual online outlets. If you’d like to build your own ESP USB stick, all the files are over on the Gits.

Thanks [lageos] for the tip.

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Nerd-Bait: ESP8266 + ILI9341 Screen

In honor of my-own-damn-self, we’re going to call it Elliot’s Law: “When any two interesting parts get cheap enough on eBay, someone will make an interface PCB for them.”

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And so it is with [Johan Kanflo]’s latest bit of work: a PCB that mounts an ESP8266 module onto the back of an ILI9341 color display, with user button, power supply, and an auxiliary MOSFET. Four bucks for the screen, four bucks for the ESP8266 module, and a few bucks here and there on parts and PCB, and you’ve got an Internet-enabled, full-color, 320×240 graphical display. That’s pretty awesome, and it’s entirely consistent with Elliot’s Law.

However, we almost can’t forgive [Johan] for the extreme geek-baiting. Posting the cuuuute little screen next to a Stormtrooper Lego figure is already hitting below the belt, but displaying a Commodore-64 startup screen, in what’s got to be exactly the right font and color combo, borders on being pathologically emotionally manipulative. You’re playing with our hearts, [Kanflo]!

We love projects like his ESP8266-and-RFM69 mashup and his gutted-Macintosh-planespotter-gizmo, so we’re inclined to forgive. And besides, we’re still on a high from naming our first law and we’re wondering which two eBay parts are up next.