S32K1 UART voltage levels

[Vishnu3]

Hi all,

I am using a BLE module operating at 3.3 volt UART, connected to LPUART of S32K1. Does the S32K1 support 3.3V at for its LPUART Rx and Tx? The Tx from LPUART to BLE module is working (with some hiccups) but the Rx at LPUART from BLE module is not working, I was thinking maybe the voltage levels could be an issue.

Best,

Vishnu

[Senlent]

Hi@Vishu3

you need to check the power supply of S32K1 which can work on 3.3V and 5V.

if 5V is used as power supply, then you may need some voltage levels converter.

[Vishnu3]

Hi Senlent,

Thanks for the reply. I checked my UART voltage level and it is at 5 V. Like I said, the data from S32K1 device to my target device (operating at 3.3V) is working. But the reverse path is not. Do you think it is because of the difference in voltage? 

At what voltage does NXP S32K144 register a logic high? What's the threshold? 

[Senlent · Accepted solution]

Hi@Vishnu3

Yes, I think this may be the cause of your level. You can use an oscilloscope to check it.

As i said before, S32K1 can work on 3.3V or 5V and the pin outputs voltage level depends on your S32K1 power supply voltage.