Data Sheet

divider on P0_0. VIN of
3.2V (equivalent to
865mV input on P0_0) is
0%, as this is the lowest
operating voltage of the
battery. VIN of 4V
(equivalent to 1081mV
input on P0_0) is 100%,
as this is the maximum
voltage delivered the
battery stably returns to
once power is removed
from the battery.
12:15
Dexcom TxID
32 bit unsigned integer
Encoded Dexcom
Transmitter ID that the
bridge is filtering on.
16
XBridge Protocol Level
8 bit unsigned integer
XBridge protocol level.
Indicates the protocol
level of xBridge. Note,
that currently this will be
0x01.
Upon receiving this packet, the phone app has to process it, taking the parts of the packet it
will use.
If the app determines that the Dexcom TxID is different to its own setting, it should
immediately send a TXID packet back to the bridge, and ignore the packet.
If the app is happy with the Dexcom TxID sent, it should accept the packet and immediately
send back an acknowledgement packet. The acknowledgement packet will immediately tell
the wixel to go into low power mode.
The acknowledgement packet structure is as follows:
Byte
Value
Data Type
Description
0
0x02
8 bit unsigned integer
Number of bytes in the packet (2)
1
0xF0
8 bit unsigned integer
Code for Data Packet
This packet does not include indication of the XBridge protocol functional level, as it is from
app to bridge.
Note that the wixel will otherwise go into low power mode if it does not receive an
acknowledgement or TXID packet within 3 seconds of transmitting a data packet.
Both the Data Packet and Acknowledgement packet are part of Protocol Functional Level 1
(0x01)
TXID packet
The TXID packet is sent from the phone app to the bridge to set the bridge to filter on a
single Dexcom G4 transmitter ID. This is important to ensure the bridge correctly “locks” to
the correct transmitter for a patient, and also to ensure the app only receives packets from
the transmitter of the patient it is monitoring.
The structure of the TXID packet is as follows: