Arduino Hacks

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Air Rocket Launch Pad UI Entertains Eager Kids

September 26, 2015 by 9 Comments

Last spring [Mike] built a foam rocket launchpad which was a hit with the kids in his neighborhood. But the launch system was merely a couple of buttons so the early enthusiasm quickly wore off. He went back to the drawing board to make improvements and really hit the jackpot!

The original launch system had one button for building up air pressure with a second big red button of doom for launching the rocket. The problem was a complete lack of user feedback; all the kids could do is guess how long they needed to hold the button to achieve the highest launch. This revision adds flashing LEDs to hold the attention of the wee ones but to also function as a gauge for the new pressure control system. The visually fascinating control board also includes a removable key to prevent accidental launches.

The particulars of this are as you’d expect: it’s a bunch of plumbing to manage the air pressure, an Arduino to control it all, and additional electronics in between to make them work together.

We’re especially impressed by the leap in features and quality from the first version to this one. It’s a testament to the power of quick proofs-of-concept before committing to a more involved build. Great work [Mike]!

We’ve seen rocket launchers for adults and some neat mission control panels but [Mike’s] kid friendly launch controller really is out of this world (sorry, couldn’t resist). You’ll find a video demo of this launcher after the break.

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Arduino Teaches Morse Code

September 24, 2015 by 16 Comments

You may wonder why anyone would want to learn Morse code. You don’t need it for a ham license anymore. There are, however, at least three reasons you might want to learn it anyway. First, some people actually enjoy it either for the nostalgia or the challenge of it. Another reason is that Morse code can often get through when other human-readable schemes fail. Morse code can be sent using low power, equipment built from simple materials or even using mirrors or flashlights. Finally, Morse code is a very simple way to do covert communications. If you know Morse code, you could privately talk to a concealed computer on just two I/O lines. We’ll let you imagine the uses for that.

In the old days, you usually learned Morse code from an experienced sender, by listening to the radio, or from an audio tape. The state of the art today employs a computer to randomly generate practice text. [M0TGN] wanted a device to generate practice code, so he built it around an Arduino. The device acts like an old commercial model, the Datong D70, although it can optionally accept an LCD screen, something the D70 didn’t have.

You can see the project in operation in the video below. Once you learn how to read Morse code, you might want to teach your Arduino to understand it, too. Or, you can check out some other Morse-based projects.

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Hackaday Dictionary: The ESP8266

September 24, 2015 by 40 Comments

In August of 2014, something new started showing up in the markets of Shenzhen, the hi-tech area of China where the majority of the world’s electronics components are made. This is the ESP8266, a WiFi SoC (System on a Chip) that can connect to 802.11b/g/n networks on the 2.4GHz band. It can be addressed with SPI or a serial connection, and has an AT command set that makes it behave rather like an old-style modem. Basically, it has everything you would need to connect a device to a WiFi network, with the ESP8266 chip itself handling the complicated business of finding, joining and transmitting/receiving over a WiFi network.

That’s nothing particularly new in itself: WiFi connection devices like the TI CC3000 have been around for longer, and do much the same thing. The difference was the price. While the TI solution costs about $10 if you buy several thousand of them, the ESP8266 costs less than $7 for an individual board that can plug straight into an Arduino or similar. Buy the chip in bulk, and you can get it for less than $2.

The ESP8266 is more than just a WiFi dongle, though: it is a fully fledged computer in itself, with a megabyte of flash memory and a 32-bit processor that uses a RISC architecture. This can run applications, turning the ESP8266 into a standalone module that can collect and send data over the Internet. And it can do this while drawing a reasonably low amount of power: while receiving data, it typically uses just 60mA, and sending data over an 802.11n connection uses just 145mA. That means you can drive it from a small battery or other small power source, and it will keep running for a long time.

It wasn’t an easy ship to write applications for in the early days, though: it was poorly documented and required a dedicated toolchain to work with. This made it more of a challenge than many hackers were comfortable with.  That changed earlier this year, though, when the Arduino IDE (Integrated Development Environment) was ported to the chip. This meant that you could use the much easier to write Arduino functions and libraries to write code for the chip, bringing it within reach of even the most casual hacker.

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HC-SR04 Isn’t The Same As Parallax PING))) But It Can Pretend To Be!

September 22, 2015 by 8 Comments

“It’s only software!” A sentence that strikes terror in the heart of an embedded systems software developer. That sentence is often uttered when the software person finds a bug in the hardware and others assume it’s going to be easier for fix in software rather than spin a new hardware revision. No wonder software is always late.

[Clint Stevenson] is his own hardware and software guy, as are most of us. He wanted to use the less expensive HC-SR04 ultrasonic rangefinder in a prototype. Longer term he wanted to have the choice of either a Parallax PING or MaxBotix ultrasonic sensor for their better performance outdoors. His hardware hack of the SR04 made this a software problem which he also managed to solve!

[Clint] was working with the Arduino library, based on the Parallax PING, which uses a single pin for trigger and echo. The HC-SR04 uses separate pins. Originally he modified the Arduino library to accept the two pin approach. But with his long term goal in mind, he also modified the HC-SR04 sensor by removing the on-board pull-up resistor and adding a new one on the connector side to combine the signals. That gave him an SR04 that worked with the single-pin based library.

We’ve seen Parallax PING projects for sensing water depth and to generate music. These could be hacked to use the HC-SR04 using [Clint’s] techniques.

[Arduino and HC-SR04 photo from Blax Lab]

Transparent ESP8266 WiFi-to-Serial Bridge

September 18, 2015 by 57 Comments

These days, connecting your microcontroller project to a WiFi network is pretty easy — you connect up an ESP8266 to your microcontroller project and pretend it’s a WiFi modem, using these old-school-style AT commands. But what do you do if you need to flash new code into the microcontroller? You can’t reprogram the micro remotely through the ESP8266 because those stupid AT commands get in the way.

The solution? By flashing the esp-link firmware into your ESP8266, you talk directly to the microcontroller over WiFi as if it were connected by a serial cable: the ESP8266 becomes a totally transparent WiFi-serial bridge. Now, with a serial bootloader and an ESP8266 in Wifi-to-serial bridge mode, you can reflash your microcontroller wirelessly, and then telnet in to interact with and debug the system remotely. Once you’ve fixed the bugs, you can re-flash the microcontroller: all over WiFi, without having to climb up a ladder to reach your IoT attic-temperature sensor.

To flash a connected Arduino, for instance, all you need to do is convince AVRDUDE to use the network instead of a locally-connected USB-serial cable: avrdude -p m328p -c arduino -b 115200 -P net:192.168.1.123:23 -U:yourHexFile.hex. The ESP8266 passes the data straight through its TX and RX lines to your microcontroller and everything works as if it were wired.

Configuration to allow the ESP8266 to join your WiFi network takes place on a self-hosted webpage that uses [Sprite_tm]’s esp-httpd standalone server, which makes setup pretty painless. And then after that you can simply telnet to the ESP8266 at port 23 and type away, or do anything else you would with a wired serial connection.

Although the simple bridge mode came first, esp-link looks like it’s growing to be a one-stop shop for all your IoT or microcontroller + WiFi needs. In addition to the serial bridge code, there is also a REST-based microcontroller-to-internet mode and there is bi-directional MQTT support in the wings. We haven’t had a chance to dig into these yet, so if you have, let us know in the comments.

If you want to dig in deeper, head over to [Jeelabs]’ blog for a slightly outdated tour of the project written by the code’s author, [Thorsten von Eicken]. For the most up-to-date development news, follow the very active development of esp-link in this thread on the esp8266 forums.

Retro Games On ArduinoCade Just Shouldn’t Be Possible

September 17, 2015 by 26 Comments

Making retro video games on today’s micro controllers brings many challenges, especially when using only the micro controller itself to handle the entire experience. Complex graphics, sound, game logic and input is taxing enough on the small chips, toss in NTSC color graphics and you have a whole different bear on your hands.

[rossum] set out making the Arduinocade retro game system using an overclocked Arduino Uno, and not much more. Supporting 4 voice sound and IR game controllers, the system also boasts 27 simultaneous colors all in software. These colors and the resolution feel like they’re impossible without a graphics chip to offload some of the work. While doing all of this the ATmega328p is also playing some faithful reproductions of classic arcade games.

The uses a couple of interesting tricks. Color is generated with NTSC color artifacts, where the screen is really black and white, but thanks to a delay or two in the signal generation the bits are out of phase from the reference “color burst” signal and appear on-screen as unique colors. This approach was used in the 8 bit Apple II personal computers to generate its colors, and also on the early IBM PC’s with CGA cards to drastically increase color depth. In this case, the chip is overclocked with a 28.6363 MHz crystal (a multiple of NTSC timing) and the SPI hardware leveraged to shift out all the necessary pixels. Check out how great it looks and sounds after the break.

It’s good to see an old trick on a new project and we are off to play some games!

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Automated Bubble Gun Just Because

September 16, 2015 by 12 Comments

After a recent trip to Disney Land, [Thomas] came home with an electric bubble gun. [Thomas] is a full-grown man. But since when did that stop us having fun blowing bubbles?? Obviously, a project was to be had using this fun little toy. So he decided to automate it.

So after taking some measurements with his trusty calipers, [Thomas] got on the computer and started designing an enclosure for the bubble gun using SolidWorks. It’s pretty simple. He designed it to hold the bubble gun in place, and allow him to attach a small RC servo motor in order to trigger the switch. Hooking that up to an Arduino Micro and he was now able to trigger it remotely.

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