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Original question:

AM3354: EMU1 pin

Linux/AM3354: EMU1 output a 1MHz square wave when device powerup.

Sunny Guo
Prodigy 120 points
Part Number: AM3354

Tool/software: Linux

We have a design with am3354 and use gpio3_8(JTAG_EMU1) to work as gpio. 

But we found that sometimes GPIO3_8 output a 1MHz square wave at power on boot stage.   Do you have any suggestion about how to fix this issue?

The schematic and waveform are shown below: 

  • 0
    TI__Guru* 77470 points

    Can you show the rest of the JTAG signals on the schematic, especially TRST.  It seems like the emulation block in the AM335x is active.  Do you have JTAG connected when you see the EMU1 toggle, or is this when JTAG is disconnected?

    Also, you said you see it "sometimes".  Can you be more specific?  Does it show up on all boards or just some?  Does it show up after all power ups, or just some?

    Regards,

    James

  • 0 in reply to JJD
    Prodigy 120 points

    It's resolved now.

    When I configure the pinmux of GPIO3-8 in u-boot, it never happened  again.