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TMDSSK3358 automatic boot upon power-up

Dav01
Expert 2300 points
Other Parts Discussed in Thread: TPS65910A

Hi, 

On the TMDSSK3358 eval-board, by default you have to press and hold SW5 to get the board to boot (via the PMIC TPS65910A3 -> PWRON).

Is there a simple way to get these boards to just boot on power-up (when the 5V main power is applied)

best D

  • 0
    Expert 2300 points

    Bumping this one. Any ideas?

  • 0 in reply to Dav01
    TI__Mastermind 21285 points

    Hi Dav,

    Without modification of the board, unfortunately there is not a way to obtain  an immediate boot upon application of board power.

  • 0 in reply to Michael S
    Expert 2300 points

    Seems like that yes. Can you suggest a solution for how to make this PMIC start on boot?

    Feels like a "hack" to short-circuit the pwron button as the bootloader will have to disable the "push and hold to restart" feature.

    best

    david

  • 0 in reply to Dav01
    TI__Mastermind 21285 points

    I'll take a look at the schematics and see if I can come up with an idea.

    I'll post again as soon as I have something.

     

    edit - I can say with 100% certainty that shorting PWRON will not work.  It just power cycles the board.  One of the biggest problems that I can think of would be the FTDI chip.  Without reset functionality, it's going to be hard trying to get debug messages through a USB to serial connection that is controlled by the same PMIC.

  • 0 in reply to Michael S
    Expert 1530 points

    <<Can you suggest a solution for how to make this PMIC start on boot?>>


    You need to get PWRHOLD = high :

    Unscrew four hex stands and find R27 & C25 on the board's solder side.

    Disconnect R27 from VAUX33 and connect it to C25.VBAT instead.

  • 0 in reply to sviss
    TI__Guru**** 393215 points
    Just take care that you power your board from a 5V adapter. PWRHOLD input of PMIC works up to 5.5V (absolute maximum is 7V, but this shouldn't be reached).
  • 0 in reply to Biser Gatchev-XID
    Expert 2300 points

    Thanks for info. Actually solved it by shorting PWRON after all and then immediately after power-up (in our boot-loader) disable the long-press off-funciton in register INT_STS_REG..  

    But seems PWRHOLD is easier, but won't that prevent me from using sleep?


    I looked at the TPS65217B as well (used on beagle bone) since it seems like a more simple option. Any pros/cons of using TPS65217B vs. TPS65910A for powering the AM335x.

    I need to be able to put the system to sleep and wake from an IRQ (reading the http://processors.wiki.ti.com/images/7/72/AM335x_Power_Solution.pdf it says "sleep mode" under other features for TPS65910A, but I don't see why I can't control that from the MCU over I2C!?). Anyone been using/coding these two that knows more on the whole power-control state machine of TPS65910A vs. doing it all in code?

    best
    David