MPC5675 UART issue

[arun_mohanraj]

I am using MPC5675k for a particular application. There are counter tests to validate the UART ports. Meaning we send data from 0-255 over UART from a PC and echo-back. 

Now this works well for a while, but for some reason, the Controller stops to transmit 0x11 and 0x13. The port works completely well otherwise. 

If the flash is programmed again, the counter test works for some time before eventually what is said above happens.

any help is appreciated.

[lukaszadrapa]

Hi,

0x11 and 0x13 are characters used for Xon/Xoff software flow control. This flow control is obviously enabled on PC side, so you need to disable it.

Regards,

Lukas

[arun_mohanraj]

hey Lucas,

thanks, I understand these are flow control characters.

Does the controller support flow control  ? 

[lukaszadrapa]

Hi Arun,

no, the microcontroller does not support flow control. But it can be implemented by software if needed. I used software version of Xon/Xoff flow control in AN5319:

https://www.nxp.com/docs/en/application-note/AN5319.pdf 

https://www.nxp.com/docs/en/application-note-software/AN5319SW.zip 

But be aware that even if you use Xon/Xoff in your software, you still can't send and receive data equal to 0x11 and 0x13 characters. This flow control is supposed to be used only when ASCII characters are transmitted. If you need to send and receive raw binary data, you would have to ensure that these characters are not present.

Regards,

Lukas