PN532 - no Field

[michaelreikersd]

I use the PN532 to read data from a JCOP Card.

My problem is, that some of my Prototypes generate no rf field.

I tested many things, and  finally I found out:

When I heat up the PN532 (60-100°C with hot air gun) I see on my scope that suddenly the rf field is there, and all is working well.

I can see this behavour at 4 of 7 curcuit boards, the other 3 are working well.
After cooling down the boards and repowering them, there is no field again.
When I repower them, when they are hot, all is working well.

I did the following things without success:

• Powered the Chip from an other power source
• Reseted and reinit the PN and the CPU during the power wasn't removed
• Reading Error Register (no Errors were detected)
• lower the SPI frequency from 4MHz tto 2,7MHz

Could it be, that the parts are damaged, because of hand soldering with hot air gun (380°C for 15s)?

Or do you think it's because of some part tolerance?

Please tell me your ideas, we want to start our first production series very soon.

Thank you,

Regards, Michael

[Jimmywder03]

@michaelreikersd did you do the library to work with PN532, can you send me it please to jimmy.hilario20@gmail.com

thanks for it

[michaelreikersd · Accepted solution]

We found the problem.

Our DCDC Converter generated some inteferences, which disturbed the RX- Line.

The inteferences changed it's frequency influenced by the temperature.

So It's no fault of the  PN532.

Nevertheless, thank you for the support!

Regards, Michael

[michaelreikersd]

Hi Kan!

Thx for feedback.

You are right!

I measured with our Oszilloscope and an Antenna loop.

We hadsome success on this issue.

We replaced the PN532 on one prototype which had this issue and its gone.

Sadly we don’t have more prototypes to test this solution.

So our next step is to produce a small batch of 20 pieces in an solder/pcb factory and see how this prototypes are working.

We will post again after some tests.

Regards, Michael

[Kan_Li]

Hi Michael,

Do you mean some boards just could not generate field but it can communicate with a controller, right? how did you measure the field out of the PN532? would you please provide more details on that?

Thanks for your patience!

Have a great day,
Kan

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