topic Re: Baud rate error in Kinetis Microcontrollers

Baud rate error

dporada — Wed, 01 Dec 2021 18:50:00 GMT

I am using a MKE02Z32VLC4 in a project with modbus. Communications are supposed to be 19.2k baud, but with processor expert set at 19.784k baud, I am only getting 18.87k baud.

It appears to me that the internal oscillator is not trimmed, but setting the P&E multilink to calibrate the trim does not seem to help. I don't see any easy way to measure the internal clock. Processor expert says the target does not contain the peripheral to output the bus clock.

Any ideas?

Re: Baud rate error

Robin_Shen — Thu, 02 Dec 2021 01:53:36 GMT

Hi dporada,

The Internal reference clock is factory trimmed to 31.25 kHz. But it was incorrectly set to 32.768 kHz by Processor Expert. Please try to modify the correct frequency first, and then test whether the baud rate meets your needs.

Best Regards,
Robin
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Re: Baud rate error

dporada — Thu, 02 Dec 2021 15:23:59 GMT

Robin,

This fixes the problem. Since this is a known problem, why isn't it fixed in Processor Expert or documented in some app note? This caused intermittent data problems on some of the units.

Fortunately, I found the problem before the units were epoxied. After they are epoxied, they would be trash.

Don

Re: Baud rate error

Robin_Shen — Fri, 03 Dec 2021 07:07:05 GMT

Hi Don,

Sorry for the inconvenience we bring you!
CodeWarrior has not been update for several years. For Kinetis MCUs, MCUXpresso Software and Tools is now recommended.
Here you can see this issue is fixed in Clocks Tool of MCUXpresso.

Best Regards,
Robin