Saturday, September 19, 2015

Time for Pebble Time and Smart Straps

More goes on in the comments around here than the blog itself.  I've been thinking about smart straps for a while, but it was a question from someone that really got me going.  I've been hung up on the current limitation, but then I realized I can do this with just the RFDuino.  I still use the device I carry in my pocket, I only have to reflash it for "Gazelle" which allows RFDuino to RFDuino communication.  The watch now becomes the master device.  I'll still need an iPhone app, that will handle calibration, and push the Slope and Intercept values to the watch.  The phone will still receive glucose, but it will retrieve those values from the watch.

But, once I'm happy with the calibration, I won't need to have the phone around.  I like that.

And another idea, only a theory at this point, in the future I could use the Redbear BLE Nano, in central mode paired with the G5 transmitter (not sure I want this until I have to take it though).  This would make the bitter pill of living without Raw data, and forced calibrations, and 2 hour warm-ups easier to swallow.

Continuing on the BLE Nano topic, this device will imitate a BLE Smart Heart Rate Chest Strap.  Which means, if anyone has a decent looking wearable that has bluetooth smart HRM funcionality, you can make it a "CGMS".  Not allot out there, I was hoping the VivoSmart would do that, but it uses Ant+.  Amazing, that small wearable has both Ant+ and BLE in it.

Still trying to get Central mode communication working with the Vivo or the Pebble.  I can do it between the Nano and an RFDuino, which means Gap/Gatt is working.  Or at least that I know how to code it.  Using Mbed on the Nano, not Arduino.  The web based environment isn't half bad...  Need a way to automate the Hex file upload and the serial monitor.  I like the way it centralizes things, Pebbles development website does a great job at all of this.

Interesting thing with the pebble, it appears to use both Bluetooth and BLE.  When un-paired, it doesn't advertise, like a BLE device should.  I can't get a handle on it with a sniffer.  Kind of a show stopper, hence the new hardware approach.  I welcome comments if anyone knows how Pebble does it's BLE.

Still trying to sniff traffic between the Vivo and the iPhone.  More on that I'm sure.  The goal of today's blog is to make the Phone optional, ie. only for calibration.  I want to communicate with a wearable directly, like I used to with the MetaWatch (moment of silence).

Scheming about making a wearable, maybe carving up the Fuel and using the good parts.  Spending an inordinate amount of time with the 3D printer making it work with Ninja Flex.  Printing Octopi, obligatory photo:


  1. I'm going to start working on something for my niece inspired by this blog. I looked at the xDrip-Wixel project. I think I can exclude the USB libraries and have enough space for a small lcd screen (from a dollar store kitchen timer). For debugging, I can use the serial port (USART1) and an external serial-to-usb converter. That will reduce the size of the watch as well. I may put a micro sd card on it and save data directly to it instead of using a file system. Do you have an email so we can talk directly?

  2. bicyclestreetview at gmail dot com

  3. I've been thinking about this for a while. What about putting the cc2500 in the wristband of the pebble and using it to collect the data and then doing a BLE connection to the phone? The watch would be like the gateway between the G4 and the phone and will be able to show you your current number. The watch is strapped to your wrist most of the time, and you'll only need the phone to calibrate and send data to the cloud.

  4. The smallest I think I can get the full circuit is 2.25x1x0.25 Inches. Pretty big to squeeze onto the pebble watch band. If you just mount the rfduino on the band, it's much more manageable.