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AM335x Time to control a GPIO

Sandeep Tammana
Intellectual 430 points
Other Parts Discussed in Thread: AM3354

Hello,

What is the minimum time to control a GPIO of AM3354 from the time PMIC starts powering ON? 

1) We need to make one GPIO High within 500mS from the time PMIC starts to power. Is this possible ? 

2) Is it possible to control GPIO after initialization of UBOOT ?

  • 0
    TI__Guru**** 393215 points

    Hi,

    You can control processor GPIOs only after MLO (first-stage bootloader) has been loaded into processor internal memory and MLO code execution has begun. Note that all GPIOs have determined state while processor is held in reset and at reset release time. See Table 4-1 in the AM335X Datasheet Rev. G for details. Also note that AM335X I/O pins are not fail-safe. No voltage should be applied to them before the processor supplies have fully ramped-up and stabilized. Only exception are USBx_VBUS pins, which are fail-safe.

  • 0 in reply to Biser Gatchev-XID
    Intellectual 430 points

    Thanks Biser.

    Any idea about the approximate time between "TPS65910A31 PMIC PWRONRSTn" release and "MLO code execution" to control GPIO ? Will this time be more than 500ms ?

    We will be booting from either MMC0 (uSD card) or MMC1 (eMMC)

    Regards,

    Sandeep 

     

     

  • 0 in reply to Sandeep Tammana
    TI__Guru**** 393215 points

    This will also depend on your SYSBOOT settings, and whether your boot device is first in the sequence. I would say that half a second will not be reached if you boot from the first device.