S32K144 LPUART

[raviranjankumar]

Hi,

I am working on S32K144 LPUART. I want to test UART with 921600 baud rate. I am unable to find SBR and OSR values for 921600 baud rate. I checked S32K design studio drivers with these drivers also not coming.

I am communicating with Bluetooth with 921600 baud rate. While calculating, I got SBR = 1 & OSR = 9 for 921600 baud rate. When I tested with Serial monitor this baud rate is working fine, but When I tested with Bluetooth some characters are missing. The Bluetooth is in 921600 baud rate.

Any further changes I need to do. If possible, please tell me SBR and OSR values for 921600 baud rate.

Thanks & Regards,

Ravi Ranjan

[danielmartynek]

Hi,

What is your LPUART peripheral frequency?

Regards,

Daniel

[raviranjankumar]

Hi Daniel,

  Thanks for reply. I am using clock option 1 that is 8 MHz. With this frequency I am getting 1 Mbps baud rate, but I'm unable to get 921600 baud rate. I tried with clock option 6 also that is SPLLDIV2 clock, with this frequency also I am not getting. 

Regards,

Ravi Ranjan

[danielmartynek]

Hi Ravi,

Using 8MHz peripheral clock, you can get indeed only 1Mhz baud rate (OSR = 7 (+1), SBR = 1), error +8.51% which is too high.

I don’t know your SPLLDIV2 clock frequency, but in case it is 48MHz, you can set

OSR = 12(+1), SBR = 4

or OSR = 25(+1), SBR = 2

Baud rate 923077, error only +0.16%.

Also, in this case the OSR will be higher which is recommended.

Regards,

Daniel