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Once you rip off the sticking plaster (you can simply do this with your hand), you can see the front of the sensor from one side. A white cover with the hub for the needle in the center. On the other side, one can already see the board under the transparent plastic layer. Be careful with the needle!
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The edge can be ground with a Dremel rotary tool. With the help of some pliers, one can peel off the plastic and with a bit of fine feeling one can take out the board.
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One can see the contacts for the needle on the transparent plastic. They are also clearly visible on the board.
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On the backside of the board, one can just see some unlabeled contacts.
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There are two antennas next to the big round battery. One is made of ceramics for Bluetooth and another one wrapped in Kapton tape that is probably used for the NFC transmission.
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Two chips form the core. The bigger one is a RF430, and it is responsible for RFID. The smaller one is an EM9304 Bluetooth chip.
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18条评论
The device in the Kapton tape is a temperature sensor.
Thanks for the comment!
But do you know where the NFC antenna is then?
Nathalie -
Is in the perimeter of the PCB, under the PCB, a trace that rounds it. you can see a grey circle in its circumference.
I’m looking at a 14 day Libre board and the antenna is clearly 3 parallel traces that are around the perimeter of the pc board. Looking at your pictures I would say that it appears they are on an inner layer of the board. That dark circle is where they are. And, looking at the backside of the board I see a couple of vias that allow them to connect to that inner layer. The antenna pins of the RF430 are pins 1 and 2. There is a dot above and to the left of the RF430 marking that indicates where pin 1 is. I appreciate you doing this teardown. I’m just now wearing my first Libre 2 sensor. Search the TI web site for RF430FRL152H to find the data sheet on the processor part.
Great teardown.
Stuart Diamond is very likely correct - the NFC antenna is almost certainly the dark ring around the edge of the board (on the opposite side of PCB from what you see in the photograph). NFC will need to be a coil.
What battery did you find? Can you share any markings or photos of it? Thanks!
