topic MKE04Z8VWJ4 UART0 TX issue in Kinetis Microcontrollers

MKE04Z8VWJ4 UART0 TX issue

yibinwang — Wed, 27 Jan 2016 09:03:33 GMT

I used MKE04Z8VWJ4 to do a small UART application to send and read the data from PC. Now, the Reading is okay. But, the sending is not OK. I have many times to check my code and board. There is not any issue of I found. Who can help me and give me some tips on something i missing?

Re: MKE04Z8VWJ4 UART0 TX issue

mjbcswitzerland — Wed, 27 Jan 2016 14:07:29 GMT

Carefully check the pin configuration used.

The KE famiy use a priority system for the selected function on each pin and you may have set the pin as Tx output but there could still be a function with higher priority set, which will overwrite it.

Regards

Mark

Re: MKE04Z8VWJ4 UART0 TX issue

Robin_Shen — Fri, 29 Jan 2016 01:48:22 GMT

Hi yibin

PTA2 and PTA3 are true open-drain pins when operated as output.

If you configure the PTA3 as UART0_TX function, you need to be aware it.

Best Regard

Robin

Re: MKE04Z8VWJ4 UART0 TX issue

yibinwang — Fri, 29 Jan 2016 03:39:16 GMT

Hi Robin Shen,

Yes, you are 100% right. We need to add a pull up resistor for the TX pin.

Thank again.

Jerry

Jerry Wang | 王宜斌 | Software Engineer | Branson Ultrasonics

T +86 (29) 8928 0532 | M 13891803152

Jerryw.Wang@emerson.com<mailto:Jerryw.Wang@emerson.com>