topic Re: Baudrate that UART can support in K10 in Kinetis Microcontrollers

Baudrate that UART can support in K10

yanlicheng — Thu, 10 Dec 2015 02:46:24 GMT

I use UART1 or UART2 (K10 chip) for communication, and the UART1 sysclk is 100M(core clock) , the UART2 sysclk is 50M(bus clock) .The communication protocol is modbus. When the baudrate is set to be 1152000 bps, the communication fails. K10 UART can only receive the first several Bytes, the following Bytes are missing. Then I test other baudrate value, and find that " 115200, 460800, 500000, 576000, 1000000" UART can work right; while under other higer baudrate, such as 1500000, 2500000, UART can't receive the correct frame.

Thus, I wonder if this issue results from that there is an upperlimit for UART baudrate in K10. If so, what's the upperlimit?

Re: Baudrate that UART can support in K10

Carlos_Mendoza — Fri, 18 Dec 2015 02:31:35 GMT

Hi Yanil,

The UART1 maximum baud rate would be given by 100000000 / (16 x 1) = 6.25Mbps

And for UART2 the maximum baud rate would be = 50000000/(16 x 1) = 3.125Mbps

Could you provide more information about your application? Is it a baremetal project? Which other modules are you using?

Best Regards,

Carlos Mendoza

Technical Support Engineer

Re: Baudrate that UART can support in K10

yanlicheng — Wed, 23 Dec 2015 04:09:01 GMT

Hi, Carlos:

What do you mean by " a baremetal project" . In my application, I also use module including DMA, PDB, PIT and so on. Will these affect the baudrate of "UART"?

Regards,

Yanli

Re: Baudrate that UART can support in K10

Carlos_Mendoza — Tue, 05 Jan 2016 00:09:41 GMT

Hi Yanil,

Thanks for your response and apologies for the delay.

By baremetal I mean if you are not using MQX or Processor Expert. Could you share an example project to reproduce the problem and see why the UART is not working at higher baud rates?

Best Regards!

Carlos Mendoza

Technical Support Engineer

Re: Baudrate that UART can support in K10

yanlicheng — Wed, 11 May 2016 08:12:00 GMT

Carlos, thanks a lot for your answer.Sorry for respond so late. The project is hard to describe in details. The UART module is mainly used for communication, which is based on modbus protocol. And PIT module is used for frame sync.

Maybe I should consider whether hardware circuit affects or the PIT interrupt time affects. Thanks again.