UART on kl25z

[aayushm]

What is the differnce  between UART0, UART1, UART2 on kl25z ?

What is the operating voltage of RX/TX pin of kl25z ?

[Hui_Ma · Accepted solution]

Please check my colleague comments at below thread:

UART on kl25z

Wish it helps.

Best regards,
Ma Hui

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[gibbon1]

The big difference is that UART0 has more clock options than UART1 and UART2. See system Options Register 2 (SIM_SOPT2) in the data sheet. UART1 and 2 use the same clock as runs the processor core.

In my case I'm constantly switching off the FLL clock and running the uP off the internal 4MHz clock to save power. By using the 4MHz clock to run UART0 I don't have to worry about data being sent out the uart getting corrupted.

I think there are also some features to automatically wake the uart up when the tx line toggles on UART0.

[aayushm]

Thanks gibbon1 . That is a very useful information.

Can you please tell me, What is the operating voltage of rx/tx uart line?

[gibbon1]

Generally I think they are just standard CMOS voltage levels, typically 3.3V logic. If you want actual RS232 or RS485 signal levels you need an interface chip. For development stuff I use a USB to 3.3V serial cable see link below. to talk to the processor serial port.

http://www.ftdichip.com/Support/Documents/DataSheets/Cables/DS_TTL-232R_CABLES.pdf