USB Errors on ESD test

jackchan — Sun, 22 Dec 2019 17:27:31 GMT

Hi,

I am using PN7462 for both smart card and NFC card reader.

I am suffering a problem with the ESD test.

USB communication will get lost in the ESD test but the device didn't aware of the situation.

The CPU is alive therefore watchdog is useless.

I am using like short D+/D- to simulate the ESD interference condition.

I discovered nothing abnormal from USB registers even the D+/D- is shorted

The attached is the error counts from USB ISR.

To compare the snapshots, before and after D+/D- shorts, I got some questions:

#1. I got some NAK errors (isr_err[9]) even I did NOT enable the IntOnNak_AI/IntOnNak_AO/IntOnNak_CI/IntOnNak_CO bits of command/status register, before D+/D- get shorted. Where are they from and how?

#2. There is a sent stall error (isr_err[10]). I guess it is from the enumeration process but why?

I did NOT find any abnormal during enumeration.

#3. After D+/D- get shorted, I tried several times and 2 samples attached.

One is reported truncated EOP (isr_err[8]) and one is reported bit stuff error (isr_err[13]). They are not always reported.

#4 What is the best way to detect USB interface errors. Original I think it can be detected by SOF and NAK of interrupt endpoint. Both of them could be beacons between the USB host and the device. However, I can get SOF and NAK ISRs when the D+/D- get shorted, but I think the communication between the USB host and the device actually gets lost since card insertion even is bot work anymore.

Are there any registers that need to be set to properly detect SOF/NAK behavior correctly?

Jack

Re: USB Errors on ESD test

Kan_Li — Tue, 24 Dec 2019 09:51:47 GMT

The PNEV7462 board is ok with USB certificate, please kindly refer to the following for details.

I think it should be a hardware design issue, please refer to the ref board schematics (UM10883 )and check if there is any difference .

BTW, what is the ESD voltage level performed on PN7462?

Have a great day,
Kan

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USB Errors on ESD test

Re: USB Errors on ESD test