Issues with working UART communication

[santhosh23]

Hello all,
I'm working on lpUART with S32K116 EVB, everything is working as expected if I power up the device from USB port. However, if I try to provide power supply from external Power Adapter 12V I could see unsual behaviour or unwanted signals coming from UART peripheral on logic analyzer as shown in below figure. 

Is there anything that we have to consider if we are providing external 12 V supply?

Thanks in advance!

Best regards,
Santhosh

[Robin_Shen]

Hi Santhosh,

1. Are you using S32K116EVB2Q048 or S32K116EVB-Q048?
2. J107 is used to select whether to be powered by P5V_SDA_PSW (J7 USB) or P5V_SBC (J16 external 12v). How do you set J107?
3. Which signal is the logic analyzer connected to? Is the GND signal connected?
4. Please show me the signal observed by the oscilloscope
5. Have you tested the UART project in S32K1 SDK or RTD?

Best Regards,
Robin
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