How can I find out if my MCU has any transients when powered up?

Discussion in 'The Projects Forum' started by HunterDX77M, Jul 23, 2013.

  1. HunterDX77M

    Thread Starter Active Member

    Sep 28, 2011
    I am trying to figure out if the microcontroller I'm using is known to have any transients at it's general purpose I/O pins when it is first powered up. I want to know the potential effects this could have on other circuits on the board.

    I've scoured the datasheet trying to see if anything like that is mentioned, but so far no luck. Is there anyway of find out something like this, before I hook everything up to an oscilloscope and check it pin-by-pin?

    FYI, the MCU in question is CC430F6137.
  2. LDC3

    Active Member

    Apr 27, 2013
    Most MCUs have a high impedance state for their IO pins. I believe that the IO pins are in this state until programmed.
  3. JohnInTX


    Jun 26, 2012
    That's usually the case. Assuming a good power supply/reset circuit, a good hardware design will take this HiZ condition into account and pull the pins to some benign state whenever they are HiZ. When initializing outputs, its usually best to write the initial states to the PORT flip/flops before setting the direction. These initial values will usually be what the pins are pulled to in the HiZ state so the power up/reset transition is transparent to the system.

    That said, I haven't used the CC430F6137 so I defer to the datasheet..