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Using EMU0 and EMU1 as GPIOs

Frank Wu95
Intellectual 390 points

I want use EMU0 and EMU1 as GPIOs. But they are required by the debugger like the link below. 

My questions are,

1) can we still use debugger while we are using them as GPIOs? In my case, they are using as output with high impedance, and pull-up resistors are connected.

2) can we fully control those special GPIOs using the debugger?

Thanks,

Frank

  • 0
    TI__Guru**** 393215 points
    Hi,

    Please see Errata Advisory 1.0.36 for EMU0/1 usage.
  • 0 in reply to Biser Gatchev-XID
    TI__Guru*** 125430 points
    If you're going to use EMU0 and EMU1 as GPIO, I highly suggest using them as output pins (and including an external pullup). That avoids the issue described in the advisory. If you were planning to use them as inputs, I recommend instead swapping with another GPIO on the board so that EMU0/1 can be an output and another "normal" GPIO pin can be an input.
  • 0
    Mastermind 8040 points

    To add: EMU0 and EMU1 are not strictly required by a debugger. If I recall correctly CCS has settings regarding their use and probably by default the XDS100v2 keeps them high-impedance (i.e. they will not interfere with your GPIO use), or to be sure you could cut the connection of those pins in the debug cable. If you ever need wait-in-reset mode you can still manually ground EMU0 while powering on your board and then connect using CCS.

    update: cutting the connection is probably overkill though since the XDS100v2 has 470 ohm series resistors on EMU0 and EMU1, so even if it attempts to drive one low while you're using the pin as GPIO output it should not be able to cause any harm or interference.

  • 0
    Mastermind 8040 points

    I've also posted more details about the EMU pins here and here, if you are interested to understand their purpose.

    Note that the XDS100v2 can only use a limited subset of their functionality, since it cannot use EMU2-4 at all (no hw connection) and can use EMU0-1 only as open-drain outputs (limitation of CPLD firmware).