[EMI/EMC] Properly terminating unused pins from a connector

[omarmog]

I am designing a device consisting of a controller board connected to an interface board.

The controller board routes severals pins from the MPC5674F to an internal connector. The other side of this connector, in the interface board, routes these pins to conditioning and power circuits.

However, some digital I/Os that arrive in the interface is reserved for future. Should I set these spare pins as input or output? How should be the hardware termination (open, grounded, pull-up or pull-down) for these pins?

I will then be trying to get FCC/CE certifications for this device. And I would like to know the recommendations for these spare pins in the interface board considering EMI, EMC and power consumption.

Thanks!

Omar

[davidtosenovjan]

Hi,

for unused digital pins, it is recommended that software disable both the input buffers and the output buffers of the pads in the Pad Control Register for the pins. In addition, the weak pull-down device should be enabled.