JoernL
commented
8 years ago Hi Patrick,
The outliers issue sounds strange to me, because i have never noticed such fake readings from my sensor or have not heard from another one about such a problem. So i guess it must be the 30s scan interval. In the Read_Memory() you see the "invalid trend check" comments. I have built in that check to avoid such outliers. To answer your big question: The LimiTTer fills an array (trend[j]) with all scanned trend values and compares lastGlucose variable to currentGlucose variable (trend-pointer -1). If the lastGlucose is higher than currentGlucose it knows, that glucose is falling and fetching the smallest trend value from the array. Conversely glucose is rising. An exeption is the apex case. I have find out that the libre reader sometimes displays a rising value even when the lastGlucose is higher than currentGlucose. Then the structure of the trend values are a bit different and the LimiTTer is also taking the highest trend value to emulate the original libre reader as effectively as possible. For your APS project - if you need smoother and slower acting sensor values just take the glucosePointer value. But if you need faster acting sensor readings, don't touch the Read_Memory() function. Please let me know if a change of the scan interval solve your problem.
PatrickAPT
trixing
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:
Please contact me under patrick.c.bosch@ntnu.no 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