joernl / limitter Goto Github PK

There's a little battery (silver or something?) in the sensor - or so I read - which allows it to run for 8 hours and collect data. It gets charged via the NFC process with a phone or the reader (I assume).

So, I figure, for you to make this project work, you'd need to know the minimum energy the sensors need to run, right? or the amount required to charge the sensor's little internal battery?
I'm guessing it's minuscule - a percentage of a fraction of a watt?

Hi,

I am reading the sensor every five minutes as per the original code. In the last few days of the sensor's life the NFC reading has become unreliable. I am waiting to verify this behaviour on the next sensor.

A likely scenario is that the Sensor's on-board battery is getting weak after so many reads. Yet it doesn't seem to affect the official reader to the same extent.

Does anyone else report this behaviour ? Any ideas on optimum time between reads ?

Incidentally, I substituted the Arduino and HC10 combination for the very small RFDuino board (see link below). It programs like an Arduino but the BlueTooth is built-in, Sleep mode is phenomenal - I can manage very low average current consumption.

https://evomedia.evothings.com/2014/11/rfduino-chip.jpg

For anyone interested I also dispensed with the NightScout links. My unit uses BLE advertising packets to broadcast to a number of nearby receivers. One is an alarm only - no LCD display. The others have permanently lit LCD displays and one is at the bedside, the others dotted around the house. I wanted to get away from using phone, and prefer to have these devices around the house - keeping an eye on G level is just like just like using a clock.

Regards

Bernie

Hello,

What are the differences between HM-11 and HM-17 modules? They peform equally?

And thanks for sharing this project @JoernL It is very important for all of us,

Good morning,
I have a problem with the LimiTTEr.
It has already "burned" 3 sensors.
After 4 days of use, the sensor stops working and I can not read it with LimiTTEr (which always gives me the same value) can not do that even with the Freestyle reader (which tells me that the sensor is terminated).
The only unusual thing I noticed is that xDrip+ recognize the LimiTTEr as "LimiTTerAT + REST".
Why? You may depend on what? What can I do?

Hi JoernL!

Is it possible to use a diffrent bluetooth card instead of the hm11-hm17?
For exampel Bluefruit Nrf8001 bluetooth breakout? https://www.adafruit.com/product/1697 Sorry for bad english
Best regards Daniel

Hi there,

I am about to start my first attempt at putting anything like this together. I plan to build this with the arduino primo core to reduce size a little. I was originally planning to keep the two poker-chip sized discs separate and connect them with a wire (rather than stacking them) so the part with the nfc reader could be worn on top of the libre sensor and the other part be worn next to it to reduce the added height.

I am not experienced with this sort of thing, but I was wondering if anyone has tried adding a nfc antenna* to increase the space it can be worn away from the libre sensor? I was thinking if it had a range of up to 0.5m-1m the arduino primo core could possibly be worn like a badge or button on clothing or even a necklace or earring in a 3d printed case if it had a little more reach?

*edit: would something like this work? (https://www.alibaba.com/product-detail/13-56mhz-NFC-chip-antenna-for_60328506427.html) - perhaps even sticking one inside the case and one onto the libre sensor... at US$0.25 a go it's affordable.

Thanks,

Michelle

*edit, realised this is called an antenna, not aerial

Where can I get a suitable lipo battery in the UK. Any help appreciatedesk.

Hi
I am working for a research group in Norway with the aim of developing an artificial pancreas.
We are currently us the Freestyle Libre to monitor some of our experiments.
To improve this monitoring and to simplify our set-up, we are intersted in using the LimiTTer to read the Libres.
However, to be able to do so, we have to fully understand the code executed by the LimiTTer. Unfortunately I am struggling with the function Read_Memory(), where the LimiTTer reads the Libre.
I know that the LimiTTer gets a string of trends from the Libre.
The big question is now how does the LimiTTer decide which is the "right" value to forward to the xDrip?
This is very important to us, as we have to know if and to what extent we can trust the data submitted by the LimiTTer.

Furthermore i built already a LimiTTer and ran a few tests. We are currently sampling every 30s and at a distance of up to 2cm between the Libre and the LimiTTer. It is working quite well, but i am getting outliers every so often (ex. constant values of 6.5mmol/l and suddenly one measurement at 12mmol/l).
I have a few ideas about those outliers:

1. Faulty bit in either NFC or Bluetooth communication
2. Oversampling of Libre (no data ready to be transmitted by the time of reading)
3. Wrong decision by the LimiTTer algorithm
   What's your opinion? Any suggestion from your side for those outliers?

Please contact me under [email protected]
And if you're interested in our project: www.apt-norway.com

Thank you very much for a swift reply and have a nice day.

Patrick

Hi at all, i write because have a question.
It's possible read data from LimiTTer with an ESP32 over BLE?
Anybody have an example?

Many thanks at all.

Ginomkc

My Question is: Are the 3DPrint STL-Files for the big or small version?

Hi
(Excuse me if this is the wrong place to ask questions).
I am interested in building one of your LimiTTer for my Libre. I have wondered if you have considered using either the arduino pro micro rather than the mini?
Also would it be possible to use the Blend Micro (http://redbearlab.com/blendmicro/) arduino that has built-in BLE, and is 18mm * 42mm, slightly larger than yours, but has BLE built in.
Thanks

The ESP32 could replace the ATMega easily and has built in Bluetooth so one module less needed in the end.. Any brain-work already done into that direction ?

Hi,
I've been working on developing the Limitter device in India. We only have the "Libre Pro" sensors available here which stores complete data of 14 days.
The sensor stores 15 minute trend data in one buffer and 14 days of historic data in the remaining memory blocks. I'm able to read the 15 minute trend data correctly. However the sensor NFC tag contains only 256 blocks and can store only 4-5 days of historic data. The remaining data is shown as factory locked. Hence I'm able to read only 4 days of historic data
Any suggestions on how I could read the historic data of remaining 10 days ?
Thanks !

when build the project. an error occurred with 'Glucose_Reading' was not declared in this scope
Where can we modify the code ? thanks.

Hello,

And thank you for this awesome project.
Can I use pin 5 instead of pin 4 on the HM-11?

I cannot find in code where you use this pin?

Thx.

PS: I managed to break pin4 while soldering. I got some cheap chinesse hm-11 and the golden contact got off :(

I'm glad to see projects like this. As this sensor can work only for 14 days it is very expensive for diabetics.
Is there any way to extend life of this sensor and still use it with LimiTTEr after 14 days. Looks like battery is not problem but Abbot forces you to buy another one.

Hi! Great job with the LimiTTer.
I Wonder if you could please publish the CAD file for the case?
Sorry for bad english Best regards Daniel

Hello!
Really love this project of yours.
I try to build one for myself but ran into problems. I cant seem to get hands on a Solutions Cubed BM019 (out of stock whereever I look). I live in Sweden
This is my very first time trying to build something using Arduino and I hoped it would be as simple as swapping the BM019 for any other NFC/RFID module.
I bought this out of E-bay http://www.ebay.com/itm/MFRC-522-RC522-RFID-Radiofrequency-IC-Card-Inducing-Sensor-Reader-for-Arduino-BE-/191371999374?hash=item2c8ea8f88e:g:igAAAOxyBjBTRMCs
and just tried to find the corresponding pins.

But I cant get it to read Libre sensors, the bluetooth connects as it should though so I figured its the NFC module.

Do I have to rewrite all the code for this specific module or what am I doing wrong?
Can you recommend any other NFC module that are compatible with this project?

Thank you!

Hola mi nombre es Pedro y soy padre de un niño Diabetico que usa el freestyle libre. Primero quisiera darle mi enhorabuena por el desarrollo del proyecto ya que llevábamos tiempo buscando algo parecido. Estoy deseando que comparta su diseño para poder probarlo en mi hijo sobre todo por la utilidad de guardián nocturno. Gracias por su tiempo y dedicación estoy convencido que seremos muchos los padres que se lo agradeceremos. Espero tener pronto noticias suyas

Hi,
the program is returning 62C2000.... for the first value of "str" and 0.00 for the "Glucose level" and "15 minutes-trend: ". i wonder if there is any problem with the activation of the sensor because i dont have the reader and play store don't allow me to download "liberlink".
Any idea to fix this problem?

Thanks !

Hello

I know that the xDrip is developed for Dexcom G4,and I find some codes to Interpretate the data from Wixel BT devices ，but our Limitter is desighed for Freestyle Libre and the data from two devices may be different ,have you modified the codes for the data send from Limitter .

HI! I'd love if you can update the list of components , because i can't find the right battery and bluetooth module.. And there is an error on description on module bluetooth its said "if you have Android 4 connect this cable to VCC instead of pin 3 and disable all "for Android 4" lines in the .ino file" so .. connect cable for android 4 or android 5 ?
Thank you!

the official app Librelink have released but it read a sensor which must be started by the app，so boring it is⋯⋯⋯⋯

if someone decompiled the app and transplant the algorithm that app uses to LimiTTer，something will change

Hello,

I'm trying to make an ESP32 version of LimiTTer freestyle reader, but I can't connect my ESP32 to Xdrip+ (when I scan BT devices on my phone I see my ESP32 (BT name = "LimiTTer") and pair it), but impossible to see my ESP from xdrip+ to received my freestyle raw data (the "Scan Blustooth" don't find any device...

I think that my bluetooth configuration on my ESP32 is not ok but I don't know how to make it work... Can you help me please ?

my bluetooth configuration looks like

in header
#include "BluetoothSerial.h" //Header File for Serial Bluetooth, will be added by default into Arduino
BluetoothSerial ble_Serial; //Object for Bluetooth

in setup
    ble_Serial.begin("LimiTTer"); //Name of your Bluetooth Signal
    for (int i=0; ( (i < MAX_BLE_WAIT) && !(ble_Serial.hasClient()) ); i++)
    {
      delay(1000);
      Serial.print("Waiting for BLE connection ...");
      Serial.println("");
    } 

in Send_Packet function
      ble_Serial.print(packet);

In setup, "ble_Serial.hasClient()" remains "false" (wrong use of it?)

When I arrive on the "ble_Serial.print(packet);" instruction (with a "correct xdrip packet"), I have a crash and reboot of my ESP
xDrip packet: 173647 216 100 17206

"Guru Meditation Error: Core 1 panic'ed (IllegalInstruction). Exception was unhandled."

I am sure my bluetooth configuration on my ESP32 LimiTTer code is not good but I don't know how to solve it...

Can you help me please ?

Hello,

I'm in Canada and just pre-ordered the Freestyle Libre. (I'm currently using a Dexcom G4 and an xDrip, with the xDrip+ app, but eager to try out the Libre and LimiTTer.)

Was hoping to get some guidance on some of the components -- as I'm not sure where to get this items:

• USB to TTL Serial Adapter Module
• Lipo battery 3.7V 100mAh 28x12x5mm

I can see most of the others are available on www.robotshop.com/ca.

Could anyone please post a link to where these two items available for purchase? Just want to ensure I get the right components.

Thanks,
Andy

Good afternoon,

First of all i'd like to thank JoernL for sharing this project!
I have built two limitters with exactly the same devices (HM11) explained in pdf instructions but i can't read any data from sensors. Xdrip+ connects correctly by bluetooth as you can see in screenshots but then, nothing happens. I have used the latest arduino code in github but it can't read the sensor.

I also have read this "forum" and restarted the mobile phones (even i have tried with 3 different mobile phones but i had exactly the same issue).

I have checked the wiring twice in both Limitters.

Thank you for your help!

Hi, I've build a version of the reading based on your code.
the issue I got is that the value from ReadMemory() is diffrent from what I see on the "original" reader display (for example the libre reader shows 185 while the code shows ~212 even on the ternd[]).
can you explain a little bit about the data structure you download from the tag so I can dig into this ??
thanks
Ido

Do you sell this a kit with all the parts necessary for a working unit.

As far as I can tell the code doesn't verify right now if the value is actually current and valid. I have tested with a few expired sensors and will show the last valid value.