Nrf24l01+ Using 3 ATtiny85 Pins

February 16, 2014 by Abe Connelly 15 Comments

[Ralph] wasn’t satisfied with the required 5 control pins to drive his nrf24l01+ transceiver module, so he used this circuit needing just 3 pin using an ATtiny85.

One of the key components was to effectively drive the chip select (CSN) line from the clock (SCK) line. The nrf24l01+ needs the CSN line to transition from high to low on the beginning of a communication. [Ralph] put the SCK line behind a diode, put a capacitor in parallel with the CSN line and altered the arduino-nrf24l01 library to encode extra delays for the clock line. This allowed the CSN line to be driven by the SCK line. Subsequent line transitions during transmission happen too fast to charge the capacitor, leaving the CSN line in a low state.

After tying the chip enable line high and dropping the 5V power line to 1.9-3.6V across a red LED, [Ralph] had an ATtiny85 controlling a nrf24l01+ module.

Though deceptively simple, a very cool hack that opens up a couple more lines on the ATtiny85.

Router Robot A Promising Playground For Young Hacker

February 7, 2014 by Mike Szczys 16 Comments

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[Stephen Downward] has put together a very impressive Internet controlled robot. There are so many things about his video presentation (also embedded below) which we find delightful. Notably, it’s obvious that he knows what he’s talking about when discussing everything from the electronics chosen for the project, the mechanical assembly and the issues with its current state, as well as the software backend that gives him control of the rover.

The bulk of the rover is the Linksys WRT-54G router which he picked up at a thrift shop. This has been a popular model for building rovers for quite some time. [Stephen] is not driving directly from the router’s serial port, but that could be an adventure for him down the road. For now he’s using an Arduino Mega along with an Ethernet shield to connect the motors to his network. The IP camera on the front gives him the video feed to operate this completely over the Internet using his own program written in C#. He mentions that the CD wheels he has aren’t ideal because of their thin tread area (covered in masking tape) and the inaccurate mounting which leaves one of them at an angle. He’s hoping to design and print his own. He plans rent some time on a 3D printer at the local University when their 3D printing service comes back online.

We think the hardest part with robot building is getting your first platform up and running. Now that he’s got that it’s a matter of making improvements and add-ons. Since he’s got the I/O of the Mega at his disposal we’d like to see him implement a bunch of different sensor: line following, bump sensors, distance sensor, heck… maybe someday he’ll scavenge some Lidar for it!

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Are We Not Indestructible? We Are Quiz Buttons!

January 31, 2014 by Kristina Panos 14 Comments

In what we hope is a new trend in interviewing, some of the people at [Anthony]’s place of work asked him to make some wireless quiz buttons. He took the task quite seriously, making them extremely robust and low-power.

[Anthony] is experienced in the button arts, having made this party push button for a wedding reception. His design for the quiz buttons is a little different. Each button has an Arduino Pro mini and an nRF24L01 wireless RF module. On the receiver side is an Arduino Pro micro and an another RF module. A connected PC captures the serial data and displays the pressed button’s ID. It also shows the order in which subsequent buttons were pressed and the time elapsed between them.

The really notable part of this build aside from the awesome laser-cut MDF Devo energy dome button housings is the extremely low power consumption of the transmitting Arduinos. [Anthony] has designed them to go into sleep mode which disables all on-board circuitry and only wakes on interrupt. He removed the power LED and the voltage regulator since they run on 2-AA batteries. The voltage regulator was drawing more than 25mA in sleep mode. Because of these mods, each button consumes < 1μA, which is less power than the batteries can self discharge over their lifetime.

[Thanks Jef]

Fail Of The Week: Reverse Engineering A Wireless Energy Monitor

January 30, 2014 by Mike Szczys 58 Comments

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[Afonso] picked up a cheap energy use monitor a few years back. He really like the data it displays about his home’s electricity, using a sensor to gather this info and a display that communicates with it wirelessly. But there is no option to log or dump the data. He set out to reverse engineer the wireless protocol in order to extend the use of the system. As the name of this column implies, he failed to get this working.

The hardware above is a 433Mhz transceiver that he rigged up as test hardware. It sounds like he’s assuming the monitor works on this band, which could have been his first misstep (we really don’t know). The speaker is there to give audible confirmation that he’s receiving something from the transmitter. This is where things start to get pretty weird. White noise was coming from the speaker, but when he stepped away from the bench it stopped. He was able to measure a regular pattern to the noise, and proceeded to place the speaker next to his computer MIC so that he could record a sample for further analysis.

Fail of the Week always aims to be a positive experience. In this case we’d like to have a conversation about the process itself. We agree that connecting a speaker (or headphones) should help get your foot in the door because your ear will recognize a rhythmic pattern when it is received. But with this noise, measuring the timing and recording a sample we’re not so sure about. Given the situation, how would you have soldiered on for the best chance at successfully sniffing out the communication scheme used by this hardware? Leave a comment below!

Fail of the Week is a Hackaday column which runs every Wednesday. Help keep the fun rolling by writing about your past failures and sending us a link to the story — or sending in links to fail write ups you find in your Internet travels.

Electric Imp Thermal Printer

January 25, 2014 by Kevin Darrah 8 Comments

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If you’re the type of person that doesn’t mind having a pocket/purse full of crumpled receipts, then maybe you should check out this tutorial from [tombrew] on giving a thermal printer internet-connectivity.

For some of us, there’s something kind of cool about thermal printers, but it’s probably not the kind of project you’d want to burn a lot of calories on. As a developer over at Electric Imp, [tombrew] agrees with this statement, but since the Electric Imp contains both a WiFi module and processor built in, it makes it pretty easy to get your thermal printer printing off the daily weather, stock prices, news headlines, etc… In fact, the claim here is that you could have this project completed before you even finish your morning coffee… knock on wood!

From a hardware standpoint, the project is pretty straight forward; an Electric Imp with breakout board, thermal printer, and a power supply are pretty much all that’s needed. Local communication between the Electric Imp and the thermal printer is accomplished through a simple serial interface. With the roll-out of the new Electric Imp IDE a few months back, we were introduced to ‘Agents’. This is kind of a neat concept, and this tutorial breaks everything down, but basically the agent is server-side code that runs in the ‘ImpCloud’, thus giving your Electric Imp more power and capabilities to deal with complex APIs. Also, handling images (like something you want to print) can take up a ton of memory, so for this project, the agent is used to send down slices of the image you want to print one at a time. This project is just the beginning of what [tombrew] has planned, so we can’t wait to see more insanely detailed tutorials.

HackPhx Winter 2014 Hackathon Winners

January 24, 2014 by Todd Harrison 9 Comments

The HackPhx Winter 2014 hackathon was held at Heatsync Labs hackerspace in Mesa, Arizona, USA. The advertised theme was “Arduino Wearables”. Participating attendees were randomly placed on teams evenly distributed by their disclosed skills across all teams. There were 10 teams with 4 to 5 members per team competing for two winning spots.

Each team had to build an amazing wearable project utilizing the secret ingredient which was Seedstudio’s Arduino-compatible Xadow wearable platform and add-ons. The Xadow is similar to the Arduino Leonardo and participants used an Arduino cross compatibility and pin mapping chart to assist in development.

Top prize was the Judges’ prizes for the best completed and documented Xadow wearable team project. The second prize was the Jury’s prize given to the team project that the other teams liked the most regardless of event criteria.

Read more about the winning teams and watch their presentations after the break.

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Move Over, Google Nest: Open Source Thermostat Is Heating Up The Internet Of Things

January 18, 2014 by Kristina Panos 25 Comments

In the wake of Google’s purchase of connected devices interest Nest, the gents at [Spark] set about to making one in roughly a day and for a fraction of the cost it took Nest to build their initial offering. [Spark]’s aim is to put connected devices within reach of the average consumer, and The Next Big Thing within the reach of the average entrepreneur.

The brain is, of course, [Spark]’s own Spark Core wi-fi dev board. The display is made of three adafruit 8×8 LED matrices driven over I²C. Also on the bus is a combination temperature and humidity sensor, the Honeywell HumidIcon. They added some status LEDs for the furnace and the fan, and a Panasonic PIR motion detector to judge whether you are home. The attractive enclosure is made of two CNC-milled wood rings. The face plate, mounting plate, and connection from the twistable wood ring to the potentiometer is laser-cut acrylic.

[Spark]’s intent is for this, like the Nest, to be a learning thermostat for the purpose of increasing energy efficiency over time, so they’ve built a web interface with a very simple UI. The interface also displays historical data, which is always nice. This project is entirely open source and totally awesome.

If you have an old Android phone lying around, you could make this open source Android thermostat.

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