Data Format
The device sends ASCII data the form of:
AAAAXXXYYYZZZ\n
where
AAAA = 16-bit sequence number, hexadecimal
XXX = 10-bit X-axis data, hexadecimal
YYY = 10-bit Y-axis data, hexadecimal
ZZZ = 10-bit Z-axis data, hexadecimalThese values are sent around 100hz, or every 10 milliseconds, whichever is faster. Axis data ranges from 0000 to 03FF.
NOTE: the older PCB revision boards were originally flashed with code that sent axis data as four characters, so the data format was: AAAAXXXXYYYYZZZZ\r\n. Note that it also had a carriage return.
LED Indicators
There are two LEDs on the board that indicate the status of the bluetooth connection.
Green/Red alternating : board is on, no rfcomm connection
Green solid/Red blinking : rfcomm connection established with host
Wrist Strap Information
There are two wrist strap designs that worked well for me. If you have any other ideas please let me know.
Design 1: Store bought velcro ties
- Two side-by-side JT&T 8" Strip-Ties from Micro Center, SKU 651851
- Cut a small strip of 2" wide hook-sided velcro and put it on top of the two straps to hold them together (picture - strip is under straps)
- wrap battery and accelerometer in 1.5" bicycle tube section and slip velcro strap through (picture)Design 2: Custom velcro strap
- Cut hook-sided and fuzzy-sided velcro according to diagram
- Sew them together as indicated in the diagram
- I ironed (melted) two layers of clear plastic onto the fuzzy velcro to make the slot (the buckle part) stiff.
- it looks like this and is a bit more comfortable than the other design
Battery Information
Batteries are useful because they power the device. The device won't run without batteries. See the connector pinouts section for details on making a battery cable.
Bluetooth CTS/RTS
You need to short the CTS and RTS pins of the bluetooth part for normal operation if you are building your own board. This is not reflected in the schematic or PCB.