Tag Archives: bluetooth

An Android reflow controller that anyone can build

via Dangerous Prototypes


Andy Brown published a new build, an Android reflow controller:

 The only surface mount device on this PCB is the MAX31855 and it has a low number of generously spaced pins. I eschewed my hot air gun, previous reflow oven and hot plate in favour of a plain old iron and the tack-soldering method because I wanted to show how easy it is to assemble this PCB and you can see me soldering the MAX31855 in the video that accompanies this article. No laughing at the back please; it’s hard to solder from behind a video camera!

Project info at Andy’s blog.

Check out the video after the break.

Android-based Reflow Brings Solder Profiles to Your Lab

via Hackaday » hardware

[Andy Brown] is a prolific hacker and ends up building a lot of hardware. About a year back, he built a reflow oven controller. The board he designed used a large number of surface mount parts. This made it seem like a chicken or egg first problem. So he designed a new, easy to build, Android based reflow controller. The new version uses just one, easy to solder surface mount part. By putting in a cheap bluetooth module on the controller, he was able to write an app which could control the oven using any bluetooth enabled Android phone or tablet.

The single PCB is divided into the high voltage, mains powered section separated from the low power control electronics with cutout slots to take care of creepage issues. A BTA312-600B triac is used to switch the oven (load) on and off. The triac is controlled by a MOC3020M optically isolated triac driver, which in turn is driven by a micro controller via a transistor. The beefy 12Amp T0220 package triac is expected to get hot when switching the 1300W load, and [Andy] works through the math to show how he arrived at the heat sink selection. To ensure safety, he uses an isolated, fully encased step down transformer to provide power to the low voltage, control section. One of his requirements was to detect the zero cross over of the mains waveform. Using this signal allows him to turn on the triac for specific angle which can be varied by the micro controller depending on how much current the load requires. The rectified, but unfiltered ac signal is fed to the base of a transistor, which switches every time its base-emitter voltage threshold is reached.

For temperature measurement, [Andy] was using a type-k thermocouple and a Maxim MAX31855 thermocouple to digital converter. This part caused him quite some grief due to a bad production batch, and he found that out via the eevblog forum – eventually sorted out by ordering a replacement. Bluetooth functions are handled by the popular, and cheap, HC-06 module, which allows easy, automatic pairing. He prototyped the code on an ATmega328P, and then transferred it to an ATmega8 after optimising and whittling it down to under 7.5kb using the gcc optimiser. In order to make the board stand-alone, he also added a header for a cheap, Nokia 5110 display and a rotary encoder selector with switch. This allows local control without requiring an Android device.

Gerbers (zip file) for the board are available from his blog, and the ATmega code and Android app from his Github repo. The BoM list on his blog makes it easy to order out all the parts. In the hour long video after the break, [Andy] walks you through solder tip selection, tips for soldering SMD parts, the whole assembly process for the board and a demo. He then wraps it up by connecting the board to his oven, and showing it in action. He still needs to polish his PID tuning and algorithm, so add in your tips in the comments below.

Filed under: hardware

App note: Simple wireless bluetooth stereo audio system for outdoor use

via Dangerous Prototypes


Old app note from Maxim Integrated on DIY portable bluetooth audio system. Link here

When people want portable music, they usually rely on battery-powered audio devices. With a bit of engineering blood (or curiosity) running in your veins, it is not difficult to build a wireless Bluetooth® stereo audio system that can be controlled with any device that has a Bluetooth connection and a music player.

TruPlay- Hacking into an OVC3860 based bluetooth A2DP adapter using the MSP430

via Dangerous Prototypes


TruPlay –  controlling bluetooth A2DP devices using MSP430and OVC3860  from Rohit Gupta:

I wanted it to 3D Print a new case but couldn’t so, made a PCB that would sit on the Top of the adapter and command it. I was lucky to have a 3.3V Regulator inside the adapter so, an extra regulator was not required. For the project i used the MSP430G2553 microcontroller in a TSSOP20 package running @ 16Mhz and programmed using Energia! I added some standard condiments like a LED and an extra SMD tactile switch to further expand capabilities.

Project details at Rohit Gupta’s blog.

Check out the video after the break.

Radio Pt. 3 (OpenBeacon, HPSDR, Ruling Drones)


The thirty-ninth meeting will feature an update on the HPSDR project, which we first heard about back in October 2010 at OSHUG #5. There will also be talks on Bluetooth Low Energy programming and OpenBeacon, and making drones play by the rules.

Low Power to the People - take back Bluetooth Low Energy control!

 —Programming BLE the hard way: bare metal programming of nRF51 BLE tokens for fun and profit.

The talk will start with a brief overview of the Bluetooth Low Energy advertisement protocol and how to implement bare-metal BLE on top of the ARM-based nRF51 chip — without using the manufacturer provided Bluetooth stack. The general development flow will be explored along with some useful examples, closing with some mischief that can be caused using this knowledge :-)

The latest version of the OpenBeacon tag design is supposed to be the ultimate hacking, fuzzing and pen testing tool for Bluetooth Low Energy. The hardware schematics and the PCB layout were released under the CC attribution license. We strongly believe that the future of the Internet of Things can be privacy enabled and can work distributed, without selling your soul to large cloud services.

Milosch Meriac has over 20 years experience in the information security business and hardware design. He is currently living in Cambridge where he works for ARM on securing the Internet of Things. In his private time he loves making and grokking things. He is currently playing with RGB strips to create light paintings.

Milosch is the co-founder of active and passive RFID open source projects like Sputnik/OpenBeacon, OpenPCD and OpenPICC, and is committed to RFID related security research. He broke the iCLASS RFID security system and was involved in breaking Mifare Classic security.

As a member of the Blinkenlights Stereoscope Core Team Milosch designed the 2.4GHz OpenBeacon-based dimmmer/Ethernet dardware that was used in the Toronto City Hall Installation. As one of the three maintainers of the former Xbox-Linux Project he helped to break Xbox security and to port the first Linux system to the Xbox. His focus is on hardware development, embedded systems, RF designs, active and passive RFID hardware development, custom-tailoring of embedded Linux hardware platforms, real time systems, IT-security and reverse engineering.

OpenHPSDR Update

A review of hardware and software progress of the High Performance Software Define Radio, an open source hardware and software project being developed by an international group of ham radio enthusiasts.

John Melton has held a ham radio license since 1984 and has developed several open source Linux applications, including ground station software for working digital satellites and software defined radios. He is a retired software engineer after 48 years developing software for several computer manufacturers including Burroughs Corporation, ICL, Sun Microsystems and Oracle Corporation.

Ruling Drones

The danger of drones not sticking to regulations have been a challenge that has been recently in the news. An attempt is being made to see if it would be possible to produce notification when regulation is breached. The plan is to use ArduPilotMega and use a modified version Arducopter so geofencing could be achieved in various areas and a GSM interface is going to be used communicate to the ground monitoring station. The modification of flight controller and ground controller in future would involve the ability to verify authenticity of the geofencing and update the geofencing over the air using GPRS/3G/433 Mhz link and usage of TPM to verify the changes to the code applied.

Anish Mohammed has been an electronics hobbyist and software hacker since his early teens. He spent almost a decade in research and development in security and cryptography. He has most recently developed an active interersts in crypto currency space and ethics of AI (Dexethics.com). He is currently on the board of advisors for Ripple Labs and EA Ventures. He is a confirmed UAV addict who owns a dozen AHRS/Autopilots, both open and partially closed, with interests in multicopters, fixed wings and rovers.

Note: Please aim to arrive by 18:15 as the first talk will start at 18:30 prompt.

Sponsored by: