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TMS320F28069MPZT - why are some pins HIGH on power up by default ie without any program on it.

 I just designed a board using TMS320F28069MPZT. When the board came in,  I powered the processor up and I haven't added any firmware yet, some pins look HIGH by default.

I was expecting them to be all input hi-Z by default. This is dangerous, I could have damaged some i/o pins especially ones I was expecting to be inputs are being driven by buffers from input devices, if the GPIO stays high by default then its same as connecting the output pin of two devices which can lead to a short circuit. Are some pins on 

TMS320F28069MPZT supposed to be HIGH by default?

thanks

Subrat

  • Hi Subrat,


    By default, some of the GPIOs are pulled up and hence we use GPxPUD register to pull the same down whenever required.

    Refer the TRM of F28069 to get more info; esp. Figure 1-73 onwards : for eg.

    Regards,

    Gautam