CC2541 I/o output on reset

The default status of IO should be GPI after reset. You can check PxSEL and PxDIR registers after reset them.

When the device is in reset all pins are configured as inputs with internal pull-ups. As soon as the device leaves reset the pins will be configured to whatever register settings you have defined in your SW.

Best regards,
Fredrik

Can I please get confirmation that a reset pin (internal pull up set as an input) if probed will be high? 

As I mentioned in my initial post I have a fet on the I/O with a pull down resistor and upon reset the l/O line goes high activating the fet very briefly until I am able to set the I/O low with software. Due to what the fet controls this is an issue.

Can anything be done to solve this reset issue?

Great, thank you for confirming my understanding. One last question on this before I mark it as answered. To confirm their is no firmware magic that can be done in the form of messing around with the linker or other lower level memory that would change the boot configuration. 

Thanks!

Hi Ansgar,

The reset state of GPIOs is 100% HW controlled. There is no FW magic that can change this.

Cheers,
Fredrik

Thanks!

Hi Ansgar,

You can make the pull down resistor much smaller than the internal pull-ups. The data sheet says typical value is 20K Ohm, so if you use a 5K pull down, the voltage should only go up to 1/4 DVDD for the brief period of time before the firmware turns the pull-up to a pull down. Depending on which FET you are using, this may be below the gate-(source-drain) threshhold.