XMC4500 USIC UART stops to work if I enable fSYS to use fPLL

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Hi Everybody,

After fixing the USIC UART issue:
https://www.infineonforums.com/threads/5530-XMC4500-UART-only-generating-interruption-for-special-ke...

I got these issues again if I set the bit SYSSEL at SYSCLKCR to use fPLL as System Clock.

The serial console output works correctly, but the UART input is not working. The issue is very similar to previous issue:

Some keystroke pressed at minicom serial console are generating interrupt:

q e t y u i p
a d h j k l
x c b m

But the character is not at OUTR register.

Other keystroke doesn't generate an interruption at all:

w r o
s f g
z v n

Why after enabling fSYS to use fPLL I got an issue that I already fixed?

The fPLL clock is correct, it is configured to 120 MHz.

After mapping EXTCLK output to P0.8 and config fEXT=fPLL/480 I can get a consistent 250 KHz output at pin P0.8.

Please Infineon, help me to fix it. My customer is losing his confidence on XMC4500 because these USIC BUGs.

BR,

Alan
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jferreira
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Hi,

Are you using the start up files and XMCLib?
Find attached an example of a command shell for XMC45. It is configured at 115200 Baudrate, 8 data bits and 1 stop bit.

Regards,
Jesus
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Hi Jesus,

Thank you for the help!

Yes, the initialization is based on XMCLib example, but it is not the same files.

You can see the files here: https://bitbucket.org/nuttx/nuttx/src/21eff99d72d3c9623420734d716dd9710bda7ea7/arch/arm/src/xmc4/?at...

xmc4_clockconfig.c is the setup of the clock
xmc4_lowputc.c is the low level UART/USIC initialization
xmc4_serial.c is the serial driver that handle IRQs and read/write data to serial.

Other important file to look is configs/xmc4500-relax/include/board.h

BR,

Alan
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