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CC2541: i/o port pins goes high when powered up

Athul P Satheesan
Intellectual 710 points
Part Number: CC2541


Hi,

I have a custom board using CC2541 in which Port 1 is used as gpio output port. The problem is, when i power up the device all gpio pins becomes high. Since i have connected some output devices to the pins, the devices are turned on. i noticed that there is a register P1INP in which the internal pull up/pull down is set. the reset value of the register makes it 0 and hence the pins are pulled up. How can I change this? is there any way to solve this problem? 

  • 0
    Guru 735685 points
    If I remember correctly, all io pins are set to GPI. I suppose you can set the pins that you connect to devices to proper GPO status to solve your issue.
  • 0
    TI__Guru** 106705 points
    Hi Athul,

    As you have seen all IOs are configured with internal pull-up in reset. When the device boots the pins will have this configuration until your application code starts running. There is no way to change this. Note though that P1_0 and P1_1 do not have internal pull-ups and can be used for signal where this is a problem.

    Cheers,
    Fredrik