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AM4372: Configuration pins of the boot source common to UART

albgarc2014
Genius 3295 points
Part Number: AM4372

Hi TI!

I need to use pins A19 and B19 as UART5_TX and UART5_RX respectively as the linux command output.
These pins are also used to configure the boot source. So they have two external resistors (pull down) connected to configure the boot source.

Can this generate a conflict?

I imagine that the UART5_RX (B19) must be connected (physically) to an external device after boot, otherwise there will be 3.3V on the B19 pin at power on and it will not boot.

Is this analysis correct?

Thanks very much. 

Best Regards. 

  • 0
    TI__Guru*** 131288 points

    Hello albgarc2014

    Thank you for the query.

    Is there a diagram that you could share.

    Regards,

    Sreenivasa

  • 0 in reply to Kallikuppa Sreenivasa
    Genius 3295 points

    Hello Sreenivasa, 

    Thank you very much. 

    Here the diagram. 

    Please note that, B19 and A19 pins are used to configure the boot source. I need to use the B19 and A19 as UART5 too. 

    1-) With the attached schematic the AM4372 starts correctly (according to the boot source selection pins)? After booting linux A19, B19 can work as UART5?

    2-) I imagine that B19 (UART5_RXD) must not be connected to any external chip. Because an external chip will put 3.3V and change the boot source selection. Am I right?

    3-) In this sense, if I use UART5 for linux command output, I would have to connect B19 (UART5_RXD) to a USB-UART bridge chip after linux starts. Am I right?

    Thank you very much. 

    Best ragrds. 

     

  • +1 in reply to albgarc2014
    TI__Guru*** 131288 points

    Hello albgarc2014

    Thank you for the inputs.

    With regard to the diagram you shared, the statements 1..3 makes sense.

    Pease note that the bootmode inputs should not change after reset to ensure the right configuration is latched.

    If there is any change at the inputs during latching, the boot configuration may not repeat.

    Regards,

    Sreenivasa