AM4372: NAK occurred in usb controller

Sung-IL

Part Number: AM4372

Dear Champs,

My customer found NAK was occurred while USB communication with USB host of PC as below.

They resolved this issue by flushing RX FIFO in the USB controller, but they would like to check with us if there are possible other causes NAK response in the USB controller. Can EMI or other make this NAK in the USB controller?

They implemented USB bulk mode by themselves, but this NAK was comes from USB controller.

Now, they implemented the flushing of RX FIFO after 'Vendor_request(0x41)' in above and they want to check if this is right and if there is other issue to be considered.

Could you please let me know your opinion on this?

Thanks and Best Regards,

SI.

over 5 years ago

0 Nick Saulnier over 5 years ago

TI__Guru** 108980 points

Hello SI,

What software is running on the AM437x?

Regards,

Nick

0 Sung-IL over 5 years ago in reply to Nick Saulnier

TI__Mastermind 31440 points

Hi Nick,

They are using Thread-X RTOS and they port it on AM437x by themselves. I'm not questioning about SW implementation, but about USB IP and USB controller.

Thanks and Best Regards,

SI.

0 Bin Liu over 5 years ago in reply to Sung-IL

TI__Guru**** 177101 points

Hi SI,

From the HW or USB controller's perspective, as long as the USB endpoint RX FIFO is not empty, the controller will NAK the OUT packet from the USB host.

Processors

Processors forum

AM4372: NAK occurred in usb controller