DRA821U: Changing UART0 & 3 Baudrate

Jack

Mastermind 9575 points

Part Number: DRA821U

Hi TI

Could you please help us to change the baud rate of UART 0 and 3?

We'd like to change the following ports.

- serial0 = &wakeup_uart0; => /dev/ttyS0 to 230400

- serial3 = &main_uart1; => /dev/ttyS3 to 19200

In TRM, two registers, DLH and DLL, are the same as below, but when you read them, you can read completely different values.
I tried to force change and test it, but UART is not working.

The results of /dev/ttyS3's DLH, DLL, and MDR are as follows.

Thanks.

Regards,

Jack

over 2 years ago

0 Keerthy J over 2 years ago

TI__Guru**** 167700 points

Hi Jack,

Stty command can be used from Linux user space to change baud rate.

I believe you won't use this as console.

www.google.com/.../

Best Regards,

Keerthy

0 Kim DongSeuk over 2 years ago in reply to Keerthy J

Intellectual 709 points

HI, Keethy

We have a problem with using wkup_uart0(tyS0).
If the baud rate of the port is set to 115200, communication is made with 230400. That is, baudrate *2.

The link below addresses a similar issue. Is it the same question? Is there a solution?

We used SDK8.04.

e2e.ti.com/.../4519484

Best Regards,

dongseuk

0 Keerthy J over 2 years ago in reply to Kim DongSeuk

TI__Guru**** 167700 points

Hi Dongseuk,

WKUP_UART is by default used by the TIFS firmware that runs on the M3. That sets up the baud & hence if you try to
use from Linux you will see Issues. Also TIFS is shared as a binary which is part of the combined tiboot3.bin. So we cannot
really control WKUP_UART from Linux.

If you check the k3-j7200-common-proc-board.dts the wkup_uart0 is reserved for system firmware aka TIFS.

- Keerthy

0 Kim DongSeuk over 2 years ago in reply to Keerthy J

Intellectual 709 points

HI, Keety

We will change h/w to use another uart.

Thanks,

Regard

Dongseuk

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DRA821U: Changing UART0 & 3 Baudrate