AM2431: AM243x SDK Bootloader: Conditions and Timing for Calling pinmux_init()

Danilo A.

Part Number: AM2431

Hi Team,

Posting on behalf of our customer.

I am working with the AM243x MCU+ SDK and customizing the bootloader (e.g., sbl_ospi). I would like to confirm the correct usage of the pinmux_init() function in this context.
Specifically, I have the following questions:

Is it acceptable to call pinmux_init() at the very beginning of the main() function in the bootloader?
Are there any prerequisites or conditions that must be met before calling pinmux_init() (e.g., unlocking MMRs, clock initialization)?

I am using the following SDK version:
mcu_plus_sdk_am243x_08_03_00_18

Any guidance or best practices regarding the correct initialization sequence in the bootloader.

Regards,

Danilo

3 months ago

0 Meet Thakar 3 months ago

TI__Genius 17420 points

Hi Danilo,

Danilo A. said:
Is it acceptable to call pinmux_init() at the very beginning of the main() function in the bootloader?

This is possible and you can call it at the very beginning of the bootloader.

Danilo A. said:
Are there any prerequisites or conditions that must be met before calling pinmux_init() (e.g., unlocking MMRs, clock initialization)?

There is no particular prerequisites for this, even unlocking and locking the MMRs is done by the Pinmux APIs: https://github.com/TexasInstruments/mcupsdk-core/blob/next/source/drivers/pinmux/am64x_am243x/pinmux.c#L133

Best Regards,

Meet.

0 Kanno Itsuki 3 months ago in reply to Meet Thakar

Prodigy 50 points

Hi Meet,

Thank you for the clarification from Danilo.

I understood that pinmux_init() should be called only after Dpl_init() and PowerClock_init().
Was that a misunderstanding on my part?
At the very least, I believed that GPIO output should be done after those initializations(Dpl_init() and PowerClock_init()).

Based on Danilo’s explanation, it’s good to know that pinmux_init() can be safely called at the very beginning of the bootloader, and that the Pinmux APIs handle MMR unlocking internally.

Best regards,
KANNO, Itsuki

0 Yashraj Motwani 3 months ago in reply to Kanno Itsuki

TI__Prodigy 310 points

Hi Kanno Itsuki,

The concerned expert is out of office. Please expect a delay in response.

Thanking you

Yashraj

0 Meet Thakar 3 months ago in reply to Yashraj Motwani

TI__Genius 17420 points

Kanno Itsuki said:
I understood that pinmux_init() should be called only after Dpl_init() and PowerClock_init().

There is no such restrictions, this is sequence followed in the SBL but I don't think there is any dependency on these 2 APIs for pinmux_init.

Kanno Itsuki said:
Based on Danilo’s explanation, it’s good to know that pinmux_init() can be safely called at the very beginning of the bootloader, and that the Pinmux APIs handle MMR unlocking internally.

This is correct.

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AM2431: AM243x SDK Bootloader: Conditions and Timing for Calling pinmux_init()