AM6422: about UART0

Hello Koji-san,

Thanks for your question.

By default on the TI EVM, this is the use of different UART ports: https://e2e.ti.com/support/processors-group/processors/f/processors-forum/1276094/faq-sk-am62-purpose-of-different-uarts?tisearch=e2e-sitesearch&keymatch=Usage%2520of%2520different%2520uart%2520ports#

Firstly refer this FAQ and then you can tell me what all open questions you have.

Looking forward to your response.

Regards,

Vaibhav

Hi Vaibhav,

Thank you for information.

I know about the default UART ports, but I would like to know whether it is necessary to keep these ports as UART.

I also would like to know about:

Koji Hirohashi said:

3. Is there other method to get the information that output when UART boot?

Best Regards,

Koji

Hello Koji-san,

Koji Hirohashi said:

Thank you for information.

You are welcome.

Koji Hirohashi said:

whether it is necessary to keep these ports as UART.

Are you asking if these UART ports can be used for something else? As in for your use case/application to send or receive data to/from external sources? If that is the case, then you can do so, but that would come at a cost of the logs being not seen, and then debugging challenges might come up.

Koji Hirohashi said:

3. Is there other method to get the information that output when UART boot?

Can you explain what do you mean by UART boot? I would like to know how you are booting? What is the method of flashing the SoC and what is the primary bootmode which you would go for at the end? OSPI/xSPI or something else.

Looking forward to your response.

Regards,

Vaibhav

Hi Vaibhav,

When I go for UART boot mode, AM64 is output some information like KEYREV from UART0 console in booting.

I would go for eMMC boot or GPMC NAND boot at the end, but during of the development, for testing secure boot, I would like to confirm the information that is output from console when go for UART boot mode.

In my application, your understanding is correct, UART0 port will be used for other function.

So, I would like to know whether I should use UART0 port temporarily for console.

If there is something else for getting KEYREV information, I don't need to use UART0 port for console.

Best Regards,

Koji

Hello,

If you do not have the UART0 then you may not use the UART bootmode as the ROM uses UART0 only for dumping the SoC information & receiving the image.

As for the SoC information like KEYCNT & KEYREV, it can be received over USB DFU bootmode or using TISCI APIs at runtime.

https://software-dl.ti.com/tisci/esd/latest/2_tisci_msgs/security/otp_revision.html#sec-api-rd-keycnt-keyrev-otp

It is recommended to have UART0 since it is the port used by default for all purposes.

Regards,

Prashant