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OpenNuvoton / NUC970_Linux_Kernel

Linux Kernel Source Code for NUC970 Series Microprocessor
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Console disconnected caused the application freeze #63

Closed chenxy1988 closed 3 years ago

chenxy1988 commented 3 years ago

Dear NUC team,

Recently we met a issue related to debug console. In our product, the Uart0 as console port, and the console debug tool we use putty on PC side. The product has a LCD could be shown Qt GUI.

When we start an application with lots of debug output. Then system running well, we also can observe the data updating on lcd screen. When we disconnect the console on putty. we can observe the application was freeze on lcd until we reconnect the console on putty.

Have you ever seen this behavior , is there any special configuration in 970 serial port driver?

Thanks.

Br, Xiangyu

yachen commented 3 years ago

Hi,

Is there a transceiver for the console port? Or the UART pins are floating while console is disconnected?

Sincerely,

Yi-An Chen

chenxy1988 commented 3 years ago

Hi Yi An,

There is a USB-232 converter, USB side connected PC and serial Tx Rx GND connected to target board. The converter chipset is FT232. According your reply, i did another test: just plug out the USB cable from PC instead of close putty. The application doesn't go to freeze. I pluged in USB to pc again, close putty instead of disconnecting USB cable. The issue happens, application went freeze.

Both above operations, the UART pins are not floating.

Best regards, Xiangyu

yachen commented 3 years ago

Just a wild guess, maybe the system seems blocked because there's huge amount of garbage coming from UART RX pin. Can you disconnect NUC970's UART0 RX pin with FT232 and test again?

chenxy1988 commented 3 years ago

Sure, I'll try to remove tx/rx pin when this issue happens.

chenxy1988 commented 3 years ago

Close due to after disconnected the FT232 with target board, the issue no longer happens anymore. Thanks.