MSP430F5438A-EP: ULP Advisor: Unused GPIO

Hello,

ZHI WEI TAN said:

1) Ultra-Low Power Adviser, from Texas instrument Wiki (http://processors.wiki.ti.com/index.php/Compiler/diagnostic_messages/MSP430/10372), has suggested using "P1SEL = 0xBE" to terminate unused GPIOs. However, 0xBE which is equivalent to 0b1011 1110, contradicts the datasheet (http://www.ti.com/lit/ds/symlink/msp430f5438a-ep.pdf#page=69) such that P1.7 has no secondary function. Moreover, I would like to know why bit 0 and bit 6 would be logic 0, as to selecting its I/O functions, leaving floating pins.

The ULP advisor provides recommendations. You'll need to confirm the settings based on the datasheet as you did. Adjust P1SEL according to your design with this general recommendation in mind.

ZHI WEI TAN said:

2) I would also like to know how selecting a pin's secondary function would save power and if there is any secondary functions that I should avoid selecting, for unused GPIO.

Check out the following threads.

Configue unused pins

Power consumption and unused pins

ZHI WEI TAN said:

3) Lastly, I would like to know if there is any difference to the amount of power saved from 'output direction logic & level 0' versus 'pin's secondary function'?

I can't provide a specific amount of power, but you could measure this using the MSP-FET and EnergyTrace. If you're unfamiliar with this, please search the forum to learn more about it.

Regards,

James