TWR-KW24D512 UART issue

[luwan]

I used TWR-KW24D512 Dev Board.

The OpenSDA chip is programmed the firmware downloaded from segger website.(JLink_OpenSDA_2015-10-13.sda)

The UART 1 is configured to baud rate 115200, 8N1.

But PC fails to tx/rx frames from the dev board from the mini USB port.

Can you help point out what is the cause of the issue?

Thanks!

[franciscomezana]

Hi Lu Wang,

Sorry for my delay. Regarding the problem you're having may be caused by several reasons, however I would recommend to check the jumpers in your board.

This might be the reason you're not getting records.

Please take a look to this link in page 14, you will see the jumpers configuration, specially J17 and J18:

http://cache.nxp.com/files/rf_if/doc/ref_manual/TWR-KW2XHWRM.pdf?fpsp=1&WT_TYPE=Reference%20Manuals&...

Please let me know if you have further concerns.

[luwan]

Thanks for your response to my issue!

The jumpers are correct.

The question is that I configured MCGCLKOUT uses external reference clock(32MHz) via MCG_C1, and divide value (SIM_CLKDIV1) is set to 1 (divided by 2).

I set the UART module clock to 327678*512 based on the formula in section 53.4.3. And it is not working properly. The baud rate is set to 115200 (8N1).

But the UART works, if I set UART module clock to 32768*460.

Can I know where is the cause of this problem? Is my understanding of the manual correct?

Thanks!

Lu

[franciscomezana]

I hope you’re doing well. Sorry for my delay regarding the formula I am not very sure how did you get the numbers to set the UART. The formula comes from this:

                

Core Clock is the one you should set this is a known value.

                                       

I would check your Core Clock and the Baud rate fine adjust (BRFA).

You can see this information in page 1374 of the MKW2xD Reference Manual.

I hope this information helps.

Please let me know if you have further concerns.

[luwan]

Can you give me a sample code for initializing System Clock and Uart baud rate?

I try to configure System Clock and baud rate via manipulating MCG_C1, OUTDIV1, but they are not working.

Lu

[franciscomezana]

Hello,

I hope you're doing well. I recommend to download KINETIS-SDK: Software Development Kit for Kinetis MCUs.

Software Development Kit for Kinetis MCUs|NXP

Once you have download this, please follow this path for the UART samples:

C:\Freescale\KSDK_1.3.0\examples\twrkw24d512\driver_examples\uart

I hope this information helps.

[luwan]

Hi,

Do you have any simple example to show how the clock is initialized?

The source code is too much to get a quick start…

Lu

[luwan]

Can you give me some sample register values?

I want to set UART baud rate to 115200. And the reference external clock is 32MHz.

Thanks!

Lu