Hi
I have a problem with a RFID card reader with U2270B. Some don't recognize the card at all and some only do at very short range.
I measured the frequency at RF and coil output pins and the results were:
the working one - 122kHz
the one working at short distance - about 116kHz
not working - about 100kHz
What could change the frequency and is it possible to find out. All resistors seemed correct but I can't measure capacitors, can I find out somehow where the problem lies?
U2270B - http://www.bdtic.com/DataSheet/ATMEL/U2270B.pdf
The circuit is something like attached picture (untitled).
edit: added picture that is closer to my schematic but standby pin is grounded like in picture 2.
I have a problem with a RFID card reader with U2270B. Some don't recognize the card at all and some only do at very short range.
I measured the frequency at RF and coil output pins and the results were:
the working one - 122kHz
the one working at short distance - about 116kHz
not working - about 100kHz
What could change the frequency and is it possible to find out. All resistors seemed correct but I can't measure capacitors, can I find out somehow where the problem lies?
U2270B - http://www.bdtic.com/DataSheet/ATMEL/U2270B.pdf
The circuit is something like attached picture (untitled).
edit: added picture that is closer to my schematic but standby pin is grounded like in picture 2.
Attachments
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