How to setup FreeStyle Libre 2 and OOP2 to use a native Bluetooth connection in xDrip+

FreeStyle Libre 2 (FSL2, Libre 2) NOTE: US and Canadian versions are NOT supported

FreeStyle Libre Reader 1 (with updated firmware)

FreeStyle Libre Reader 2

OOP1

• Works with Libre 1 and Libre2 sensors.

• 2 versions of OOP1 - One for European Libre 2 sensors and another for Libre2 US Sensors

• Retrieves values from Libre sensors and applies an algorithm to convert raw Libre sensor data to obtain corrected / calibrated blood glucose values.

• NOTE: OOP1 has stopped working on most phones running Android 10

OOP2

• Works with European Libre 2 sensors only

• Closed source (not available on GitHub)

• Purpose is to decrypt the encrypted raw Libre2 values and return them to xDrip+. Then xDrip+ is responsible for the translation and calibration of these values into usable blood glucose values.

Patched version 2.3

Official version 2.4.2

Official version 2.5.3 latest version

Nightly latest source code built each night. Not thoroughly tested

Stable latest stable tested release.

NOTE: any release after 13/12/2020 should work with OOP2 as that is when it was first integrated into xDrip+.

First download and install the apps below

Uninstall Possible Conflicting Apps

Notes

Troubleshooting

Advantages

Disadvantages

OOP2 - Versions of the oop2 can be found at:

xDrip+ - latest version can be found at:

Amazon Alexa (UPDATE, no longer conflicts on Android 10 and newer)

Tile

UPDATE: With newer phone hardware and operating systems the responsiveness and connection issues seem to be significantly improved and thus are not nearly as effected, if at all, by this issue. Feel free to try using these apps with your installation after you have it working.

Use NFC feature: on

Starting bluetooth connection with libre 2 sensor: Always connect to libre2 sensors

Sensor Age or Expiry: on

Scan when not in xDrip+: on

Double Calibrations: on (optional but recommended)

Non-fixed Libre slopes: on

Check Libre Serial: on

Turn bluetooth on: on

Trust Auto-Connect: on

Use Background Scans: on

Always discover services: on

Allow bluecon unbonding: on

show Raw values in Graph: on

show Sensors infos in Status: on

Extra tags for logging: enter this value

Smooth Libre data: on

Retrieve Libre History: on

OOP algorithm calibration: THIS IS GREYED OUT AND CANNOT BE CHECKED, THIS IS NORMAL BEHAVIOUR

Settings for OOP2 Configuration

• Out of process Libre algorithm: OFF

Phone Service State: The last time the phone made a BT connection to the sensor

Bluetooth Device: Displays current status of the connection (either Connected or Disconnected)

Active device connection: Displays the status of the bluetooth bond after connection. True means the sensor is connected and bonded.

Device Mac Address: This is the hardware ID of the sensor

GATT device connected: This is the hardware ID registered in the Android BT service. Any bluetooth devices actively bonded to your phone will display their hardware ID here. The GATT and Device Address should match for your sensor hardware ID.

Request Data: Only shown with Engineering Mode enabled in xDrip+. Pressing Test for xBridgePlus protocol you can manually start a request for data from your sensor.

Received Data: This is a hexadecimal representation of the data stream coming from your sensor. If you see characters here then you are actively receiving data from the sensor. The data should change after pressing Test for xBridgePlus protocol.

Send Data: This is the data request hexadecimal stream sent to the sensor to start data retrieval. After pressing Test for xBridgePlus protocol you should see this field update however, the data may not change a the request is the same each time.

You can have OOP1 and OOP2 installed at the same time however, only one of the OOP applications will work based on the setting Out of process Libre algorithm set in xDrip+. It is my recommendation that you only use one and that should be OOP2.

OOP1 requires that the xDrip+ settings->Less common settings->Other misc settings->Out of process Libre algorithm is set to ON. For OOP2 this setting MUST BE TURNED OFF TO WORK (counterintuitive, yes but needed). When you install OOP2 the program may give a notification asking if you want this setting turned on, DO NOT Accept this notification, simply dismiss it.

Using LibreLink NFC Scans AFTER bonding/pairing in xDrip+ is completed: You can conduct NFC scans but the bonding/pairing process with xDrip+ needs to be completed first. Always look at xDrip+ and see if it is close to the 5 minute reading (ie. 4 minutes ago), if it is near 5 min, wait for the new BT reading to come in and then conduct the NFC scan. If you catch it at the wrong time it will disturb the BT process in xDrip+ and not receive BT readings, which can take a while to rebond and transmit again and sometimes a sensor BT connection can be “stolen” by LibreLink. However between these BT readings I have not had any problems executing an NFC scan followed by immediately disabling the app. I am not sure if LL needs to be disabled each time but I disable it to be on the safe side.

• What is going on? When a Bluetooth connection is made a private shared key is created that is needed to allow communication between the sensor and the calling application/device. There is a high probability that the LibreLink app or the Reader creates a new private shared key for communication during the connection. This means that after bonding, xDrip+ is not aware of the new key and will not be able to communicate with the sensor.

• UPDATE You can run the LibreLink App with xDrip+ with this LibreLink permissions change: Several users have reported that the LibreLink app can be restarted after successfully starting the sensor and receiving readers in xDrip+. In the LibreLink app Android permission you simply need to turn off the Allow Location setting. Once this is done you should be able to use the LibreLink app and xDrip+ simultaneously. I would recommend that you don't select a default app for NFC scanning and pick which app you want to read the sensor for an NFC scan. Also, DON'T FORGET, on your next sensor change to force close the LibreLink app after the initial warmup NFC scan on the new sensor. After the sensor is configured and receiving readings in xDrip+ you can then start the LibreLink app again.

Rebooting your phone: After the reboot, and after disabling or force closing the app, REMEMBER to check that the LibreLink app is NOT running. I suggest testing a reboot to see if LibreLink starts again automatically. You can look in the LibreLink app settings under Android Application settings on your phone. If it is still enabled, then disable the LibreLink app again, uninstalling the LibreLink app may be the only way to avoid this. This is to prevent LibreLink from accidentally stealing the BT bond. Also, after rebooting it will take the same 3-15 minutes to get BT readings from the sensor so be patient and plan for this if you are rebooting close to times you require a BG reading in order to bolus, meals, etc.

Battery Optimization settings: Make sure you EXCLUDE these apps from your phone’s battery optimization settings

• xDrip+

• OOP (1 or 2)

• LibreLink

• AndroidAPS (if you are using it)

2.4 GHz Wifi Routers: Some routers support both 2.4 GHz and 5 GHz broadcasting of their Wifi signal. BLE runs on the 2.4 GHz signal but avoids disruption if many devices are present on a channel by systematically jumping from channel to channel at different intervals. However, if you have the ability to turn off 2.4 GHz and only use 5 GHz in your area of use I would recommend it. Time to establish the first connection decreased significantly after doing this as well as periodic disconnects of the sensor. I have a lot of Hue lamps running in a small space and the Zigbee bluetooth network runs at 2.4 GHz. I assume this was the reason for my interference as a quick trip outside made connections MUCH faster. Every environment is different but if you are having problems I would suggest turning it off.

UPDATE: With newer phone hardware and operating systems the responsiveness and connection issues seem to be significantly improved and thus are not nearly as effected, if at all, by this issue.

Retrieving backfilled data can only be accomplished by NFC scan: Because Bluetooth readings only return a single value backfilling your sensor reading history can only be accomplished with an NFC scan. This is also useful if you lose the Bluetooth connection ( too far away from your phone for a long time, accidentally turned bluetooth off/on, rebooted phone). A simple NFC scan after a lost connection will help re-establish the Bluetooth connection as well as backfill the previous 8 hours of retrieved blood glucose values.

UPDATE: The latest version of xDrip+ allows for Bluetooth data to bring in not only the current reading but ALSO backfill history up to an hour prior. To get the full 8 hours of backfill history and NFC scan will need to be done manually.

Using Flight Mode: There are some situations which call for turning on flight mode (when taking a flight ;-), sleeping at night and you do not wish to have WIFI or Mobile connection signals operating with your phone in close range of your head) and this can cause issues with the Bluetooth communication during activation of Flight mode. When switching on flightmode on the phone followed by activating Bluetooth, blood glucose readings will be lost. The only workaround is to restart the collector in xdrip+ -> System Status -> Classic Status Page. After restarting the collector the blood glucose readings appeared again.

OOP2 and FLS2 with xDrip+ Troubleshooting Guide Post on MinimalLooper.com

• COMING SOON

LibreLink patched app no longer required You no longer need a patched version of the LibreLink app to retrieve values from the Libre 2 sensor. While you can use the LibreLink patched app, the official versions of the LibreLink app can start the first NFC initialization scan in the same manner as the patched app. There is no difference as far as NFC initialization scanning to start the sensor is concerned.

3rd party NFC scanning device no longer required 3rd party NFC scanning devices such as (Miaomiao1 (MM1) [Firmware 39], Miaomiao2 (MM2) or Blucon) are no longer needed (but can still be used) to collect readings as the sensor alone can deliver them now via Bluetooth. Less hardware means less things to go wrong, less devices to charge and a more minimalistic setup.

You will still be able to NFC scan readings with the Libre 2 Reader (version 1 with updated FW or version 2) WHEN the FSL2 sensor has been started with the FSL Reader FIRST. The Libre 2 standalone reader can still be used to scan readings on the active sensor once it is bonded via Bluetooth to xDrip+.

• You MUST start the sensor with the version first NFC scan to initiate sensor warmup with the FSL Reader FIRST. After this point other software applications will also be able to take NFC readings from the now activated sensor.

• ( It is my understanding that the Libre 2 sensor (as long as it has not established or is not trying to establish a connection) will always advertise its presence (and availability) over BLE exactly every 2 minutes (visible on any Bluetooth device that has the ability to scan for Bluetooth devices). Whichever device is first to respond to this advertisement wins the race and is the only device allowed to connect and read the sensor as a private shared key is created during the NFC scan connection process which is used to decrypt Libre2 communication. The sensor is then unavailable to other devices that do not have this private share key and might also be trying to connect. It seems that the Libre reader always wins this race whatever the “opponent”.

• UPDATE: The Libre 1 reader can be upgraded to allow scanning of Libre 2 sensors. This is a perfect option because the Libre 1 reader does not contain a Bluetooth chip so there is no way it can interfere with the FLS2 Bluetooth communication. To upgrade you need to connect your Libre 1 reader to your computer via USB and run the upgrade programs below.

• FreeStyle Libre 1 Reader Upgrade - Windows:

• https://distributionstaging.freestyleserver.com/Payloads/fsfw/UpdateFreeStyleLibre_248_159.exe

• FreeStyle Libre 1 Reader Upgrade - Macintosh:

• https://distributionstaging.freestyleserver.com/Payloads/fsfw/UpdateFreeStyleLibre_248_159.zip

• NOTE: your Libre 1 reader software version must be 2.2.9 or later to upgrade to version 2.4.8 (contains the functionality to read FSL2 sensors). Unfortunately mine was too old at 2.1.2. You can contact Abbott support to get a newer Libre 1 Reader if this is the case

Minimal hardware device setup My goal has always been to keep the medical devices attached to my body at a minimum. The Libre 2 in combination with the Omnipod system accomplished this goal (and with availability of DASH in the future, only those two devices will be needed). This point is even more crucial when I travel (both short and long distances) because the number of items and set changes for those items becomes fewer, which means I have more room for other items in my luggage. Hopefully in the future there will be a patch pump that just has a replaceable reservoir and the chip and motor system can be packaged as a retainable/reusable piece. This would cut down on waste and decrease packaging for site changes which again leads to more room in my suitcase for other things.

No more hour gaps when changing sensors Because you can start another sensor with the LibreLink app using an initial NFC scan, the current sensor can keep running and delivering readings by Bluetooth at the same time. After 20 minutes you can get readings from the new sensor but it is best to wait 1 hour for the sensor to properly internally calibrate. This means you can stop the current sensor and start up the new one (after it has been set and warmed up with the LibreLink NFC scan an hour earlier) and within 3 to 15 minutes you will have your initial calibrations and readings. Check out my other article on Libre 2 sensor insertion and calibration best practices [INSERT LINK].

Use of OOP2 REQUIRES Calibration Unlike OOP1 (which does not support calibration), when using OOP2 you are now required to make an initial calibration in order to start the sensor. This can be a single or double calibration (if you have enabled that option). This added feature solves the problem with the official LibreLink app or official Libre Reader which would report a value of LOW, when the actual blood glucose was near 100 mg/dL. The LibreLink patched app allowed for limited calibrations in a range of 20 mg/dL around the returned raw BG value. This is because Abbot stops returning a value if it is below 40 mg/dL. Since calibration is not possible in either the official LibreLink app or the Reader, inexact values would be returned (which made looping impossible). Now OOP2 forces a calibration in order to start the sensor to ensure that returned values accurately reflect actual blood glucose values.

Phone Reboot: Because the Bluetooth process has to start again when your phone reboots, you have to first ensure that you manually disable the LibreLink app (if you did not uninstall it) and be patient for the first readings to come in (3 to 15 min). This means timing phone reboots so they do not occur during critical times like correction boluses or meal and snack times.

You can't run LibreLink and xDrip+ in parallel together for Bluetooth readings. LibreLink will always try to "steal" the Bluetooth connection to the sensor and bond. If that happens, you are stuck with LibreLink for the rest of the life of the sensor. So running the apps simultaneously does not work all the time. As I mention below, you can enable the LibreLink app and do an NFC scan to get the LibreLink reading (if you need to compare, want to retrieve history for yourself or endocrinologist reports) however you should disable it as soon as you have your reading and not try to attempt this within a minute of when xDrip+ is going to retrieve its Bluetooth reading. I am not sure how using the Libre 2 reader works while doing this but I will test that at a later point.

• UPDATE You can run the LibreLink App with xDrip+ with this LibreLink permissions change: Several users have reported that the LibreLink app can be restarted after successfully starting the sensor and receiving readers in xDrip+. In the LibreLink app Android permission you simply need to turn off the Allow Location setting. Once this is done you should be able to use the LibreLink app and xDrip+ simultaneously. I would recommend that you don't select a default app for NFC scanning and pick which app you want to read the sensor for an NFC scan. Also, DON'T FORGET, on your next sensor change to force close the LibreLink app after the initial warmup NFC scan on the new sensor. After the sensor is configured and receiving readings in xDrip+ you can then start the LibreLink app again.

3rd Party NFC Scanning Devices can still be used. Yes, I listed this as a disadvantage but I also wanted to point out that if something goes wrong with the sensor and LibreLink captures control of it, you can always fall back to placing an NFC scanning device on the sensor to get readings in xDrip+. You can also use this device instead of a direct Bluetooth connection if you are more comfortable with a setup consisting of a 3rd party NFC scanning device (Miaomiao, Blucon). Sometimes certain phones do not operate well with the native Bluetooth sensor bonding and data retrieval. You can use these devices as a backup or as normal usage, either way you still have this as an option.

• If you are planning on using the FSL Reader as an NFC scanning device to take readings, you MUST start the FSL2 sensor with the VERY FIRST NFC scan to warm up the senor with the READER FIRST.

LibreView data will not be uploaded automatically Since the LibreLink app does not have a constant Bluetooth connection (because LibreLink should not be running simultaneously with xDrip+ once the sensor is actively sending bluetooth readings) then it is not receiving readings automatically from the sensor. This means that blood glucose data is not automatically being uploaded to LibreView and by extension other phones with LibreLink. I mark this as a disadvantage as I know many parents rely on this functionality as well as those that are forced to use the LibreView reporting for their healthcare provider. You can still open the LibreLink app and scan every 8 hours to get the back-filled data from the sensor into LibreLink (3 times every day [at least every 8 hours] but more scans would likely be needed to capture all 24 hours of data) but again this is a manual process.

Use of OOP2 REQUIRES Calibration While this is mostly viewed as a feature addition some people may view forced calibration as a disadvantage. There are times when a sensor needs to be replaced under less than ideal conditions. This means your blood glucose may not be in the flat stable values needed for ideal calibration, however you still need SOME readings to have a general idea of where the BG is and where it is trending until it can stabilize for calibration. Other times the sensor may not be as accurate as others but it is still functional. It will take many calibrations and some time (8 hours to a few days) to arrive at a reliable slope and intercept returning accurate adjusted values..

BT - Bluetooth

BLE - Bluetooth Low Energy

FSL - FreeStyle Libre, abbreviation for the CGM sensor produced by Abbott. Can appear as version 1 (FSL1) or version 2 (FSL2)

• Libre 1 (FSL1) - NFC only. First version of Libre sensor

• Libre 2 (FSL2) - Bluetooth and NFC. Second version of the Libre sensor.

• Libre 3 (FSL3) - Bluetooth and NFC. Third smaller version of the Libre sensor. Currently not released.

LL - LibreLink, application used to start the Libre sensor with initial NFC scan

MM - MiaoMiao, name and manufacturer of a 3rd party NFC scanning device that delivers readings via bluetooth to xDrip+.

NFC - Near Field Communication, a physical operation in which you bring the NFC sensor on your phone close to your Libre sensor to start a reading. This is often referred to as “scanning the sensor”, a “sensor scan” or “NFC scan”. This process in no way uses Bluetooth.

OOP1 - Out of Process Algorithm version 1, the 3rd party app that receives raw values (delivered to xDrip+ from the Libre sensor [by bluetooth or NFC scan]) and then uses an algorithm (very similar to the hardware algorithm on the sensor chip) to process the raw values and returns a calibrated (by the OOP1 algorithm, not by xDrip+’s native calibrations) blood sugar back to xDrip+ to either display or be further processed with xDrip+’s calibration (with a finger pick blood calibration) if needed.

OOP2 - Out of Process Algorithm version 2, the 3rd party app that receives encrypted data delivered to from the Libre2 sensor (by bluetooth or NFC scan) and then decrypts the encrypted data. Once decrypted, the data is then sent to xDrip+ for further processing, such as calibration.