Thursday, December 13, 2012

Volunteers Needed - Firmware, DSP

With my full time employer, I have little time to work on Firmware, signal processing and Bluetooth power optimization.  If you would like to contribute to this Open Source Hardware Software project, please contact me by leaving a comment.

Volunteers needed for:
  • Customize Bluetooth 4.0 stack code provided from Texas Instruments
  • Signal processing on the 8051 processor for heart rate detection.
  • Timer on/off optimization for low power.
Do you own a TI CC2540DK-MINI development kit? Then you can develop and test at home!

Are you a Product Designer or into Industrial Design?
  • We need a watch enclosure to house these electronics.
Please leave a comment if you are interested with which topic you can contribute on!
I aim to post the final project on for funding and compensation can be provided after we obtain funds, depending on level of participation.

Friday, October 5, 2012

Prototype of Pulsar Heart Rate Watch Board

Using a reflow oven (custom made), I was able to assemble the bluetooth watch board with the system on chip (SoC) part, lithium ion battery charger, LEDs, connectors, etc.  This board is the main board doing the signal processing and Bluetooth 4.0 Low Energy radio transmission of the heart rate data to a smartphone.

The crucial part to assembling a board with QFN package parts is the solder mask stencil.  The QFN parts are 0.5mm pitch (0.5mm from the middle of lead to another) which makes it almost impossible to solder without a reflow oven or a reflow heat gun.  I obtained the stencil from  For one sheet with 1.23" by 1.23" board size total cost was about $30 with shipping.  Although what you get seems like a transparency paper with some holes, it is definitely worth the time saved during assembly.

I can't wait to power up and test the prototype.
Pulsar Bluetooth Heart Rate Watch Board prototype:
LEFT: sensor connector
TOP: USB micro connector
BOTTOM: Push-Button
UNDER: LiIon Battery connector

Tuesday, September 25, 2012

Watch Board prototype has arrived

Watch Board has arrived the other day, and it looks great.  I ordered 3 for prototyping and testing the electronics.  All the parts are in except for one. Sadly it's the much needed stencil for surface mount assembly.  The bluetooth IC is 0.5mm pitch spacing so I gave up trying to put solder paste on each pin.

Look forward to assembling the electronics next week.

Bluetooth Heart Rate Monitor Project - No Chest Strap!

Hi Everyone,

Paper scale component fit check - Watch Board
I'm pushing along on this personal project but I need your sleek industrial design help.  I call it Pulsar - a continuous heart rate monitor for iPhone and Android without a chest strap, and without having to touch a metal surface every so often... it continuously takes readings and charts them on a smartphone.  There are already apps available like CardioMapper.  The electronics are almost done, being manufactured.

Please let me know if you'd like to take part in this open hardware project.  Will need 3D sketches/design and need someone who has created high volume, low cost products like a watch.  It is a useful product and a great project to build on your portfolio.