This must be useful for something. - Page 1
Forum section: electronics / projects

author: Mjolinor
author_rank: Frequent Contributor
timestamp: November 30, 2019, 10:20:27 am
content: I am diabetic and use these to monitor my blood sugar:https://www.freestylelibre.co.uk/libre/Once fitted and activated they will measure for two weeks then die so one is left with this really neat PCB that has at least a temperature sensor, battery and a RF430FRL15xH processor along with a near field antenna.It has to be useful for something. Best I can come up with is something to stick in a parcel to see what temperature extremes it has been subject to. Maybe one could stick a G sensor in and check that too or perhaps the processor has one.It seems the processor can be programmed with the Arduino software now so that's a plus.I haven't really explored the processor or anything about the thing but it sure looks too useful to throw away given the strong case it comes in.Any lateral thinking suggestions out there?

author: Nusa
author_rank: Super Contributor
timestamp: November 30, 2019, 11:03:25 am
content: Looks like it's about a $4 processor in small quantities. And you'll have a regular supply, so sure, something to play with. Figuring out how to program one on that board would be the first step.What's the battery voltage on the discarded units?

author: Mjolinor
author_rank: Frequent Contributor
timestamp: November 30, 2019, 02:18:40 pm
content: It is a 1.55 volt battery and they stay working for months after the sensor expires. I have not had one that ahs stopped yet and it is several months since I first used one.They still respond to the NFC when you read them with Android but it just says sensor expired.

author: mcovington
author_rank: Regular Contributor
timestamp: November 30, 2019, 07:49:32 pm
content: A family member of mine uses the competing Dexcom product, in which the transmitter and sensor are separate. So I am following this thread...

author: Nusa
author_rank: Super Contributor
timestamp: November 30, 2019, 08:30:12 pm
content: Need much better close-up pictures if you want any help. Both sides.Is that trio of large pads obviously used for something when the product is assembled? If not, worth tracing early on. They may be for programming.

author: Mjolinor
author_rank: Frequent Contributor
timestamp: November 30, 2019, 09:21:27 pm
content: The trio of pads are to take the sensor which is the small white triangular thing on the white circle with the small needle on.I am not looking for help getting the schematic, that's easy enough, what I am looking for is some suggestions for use. I don't want to know the temperature of parcels and a disc with lots of flashing LEDs on isn't really floating my boat.I am not about to work all this out in order to not use it for anything.The sensor has three connections. I suspect (I have not checked) that the sensor is not powered until you wear it. It comes with a really fancy holder with springs and clips and stuff so the sensor is not part of the PCB until you load it for wearing. It is then fired into you arm using a needle, once in your arm the needle retracts and leaves that bit stuck in your arm.

author: Mjolinor
author_rank: Frequent Contributor
timestamp: December 01, 2019, 08:55:05 am
content: Both sides of board.

author: SiliconWizard
author_rank: Super Contributor
timestamp: December 01, 2019, 05:00:56 pm
content: I'm not sure what your question entails. Are you interested/willing/knowledgeable in programming the MCU yourself, or do you just want to use the existing software in some way, just modifying the hardware a bit?Anyway, you can find documentation about the MCU there:https://www.ti.com/product/RF430FRL152H

author: 741
author_rank: Frequent Contributor
timestamp: December 01, 2019, 05:23:42 pm
content: Given the antenna, can you build an IOT-like cluster? As to why you might want this cluster... Each node senses its temperature and controls the heating system via local radiator solenoids and a central control unit.

author: Mjolinor
author_rank: Frequent Contributor
timestamp: December 02, 2019, 07:30:03 am
content: Quote from: SiliconWizard on December 01, 2019, 05:00:56 pmI am just looking for some potential uses. I have the data sheet and am able to modify the hardware and / or the software if required. I just want some ideas for use before I bother digesting all the verbage.

author: SiliconWizard
author_rank: Super Contributor
timestamp: December 02, 2019, 06:54:50 pm
content: If you're keen on writing your own software, I can think of many uses (but whether any of them would be of any interest to you is unknown!)This MCU embeds a 14-bit ADC, some FRAM and an NFC transceiver. You could use it as a data logger (albeit the FRAM is limited, so not too frequent measurements) for any kind of sensing you can think of.As you mentioned, it could be used as a temperature logger, but using the ADC inputs, you could also add an analog sensor, such as a humidity sensor, or an accelerometer (could be interesting to record whether something has been subjected to a shock, or to measure/log acceleration in a vehicle, etc.

author: Gribo
author_rank: Frequent Contributor
timestamp: December 02, 2019, 07:51:04 pm
content: Green house sensor network.Can it work without the battery and harvest power from the NFC antenna?