ANT Chest Strap Logger

• Forum Postings
• Check the comments for a forum thread and some more code. Should be able to interface with a Suunto strap too as someone decoded the network key. Start from the last page and work back for sample code.
• If this thing actually works, it'll be awesome

• How does ANT determine between multiple HRM's? (How do they pair?). Do they have a unique ID that you ask for? Can one listen to multiple?
• Have the app stay alive even through data dropout (leaving the room)
• Check HR accuracy vs BioHarness
• Logging to CSV? file

• The trick to getting real-time data (R-R timings) from the HRM is to switch the messagePeriod bytes around…lame! It seems to be a “magic” value for Garmin (and I assume Suunto). A change in the value does change the sample period of the USB ANT board, but it gets a bunch of dead packets with a real packet every 5 seconds or so from the HRM. Really weird!
• Also, if the board doesn't seem to be responding at all (after I took out the battery), flip the battery polarity around to reset somewhat and then stick it back in normally. Not sure why it works as it doesn't connect to the negative terminal when you do that, but it shorts something and then works for me!
• HRV Tracker is a great demo app (but doesn't draw anything). Code is well-documented and he explains the meaning of the bytes (which I paraphrased below).

• from HRVTracker

heart rate data messages are sent as: SYNC, MSG_LENGTH (=9), MSG_ID (=0x4E), DEVICE/MODEL DATA (=5 bytes), RR_TIMER(=2bytes), HR(=1 byte), CHECKSUM

          //0 - SYNC
          //1 - MSG_LENGTH 
          //2 - MSG_ID (0x4E)
          //3 - DEVICE/MODEL ID
          //4 - DEVICE/MODEL ID
          //5 - DEVICE/MODEL ID
          //6 - DEVICE/MODEL ID
          //7 - DEVICE/MODEL ID
          //8 - RR_TIMER
          //9 - RR_TIMER
          //10 - DATA COUNTER
          //11 - HR
          //12 - CHECKSUM

          //device ID data messages are sent as:
          //0 - SYNC
          //1 - MSG DATA LENGTH 
          //2 - MSG_ID (0x51)
          //3 - CHANNEL NO
          //4 - DEVICE ID
          //5 - DEVICE ID (MULTIPLY BY 256)
          //6 - DEVICE TYPE ID
          //7 - TRANSMISSION TYPE