I'm new to microcontrollers and I'm a little confused about the P3 pin on the msp430g2553.
In this tutorial it mentions setting P3DIR and P3IN for the push button, but I can't see where P3 meets the microcontroller on the board itself. The button is labelled as P1.3 on the board rather than P3.
Also, when I searched msp430g2553.h I found that P3 was defined.
Is P3 a legacy pin or is it actually used?
Best Answer
The tutorial talks about a different model of the family which may have more I/O ports; however the 2553 does have port P3.
P3 is not a pin, but an 8 bit port therefore (up to) 8 pins P3.0 to P3.7.
Whether the pins are actually available will depend on the package option.
The 20 pin package (such as on the Launchpad) doesn't have enough pins to bring them out to actual device pins (though the logic will be there on the chip; not very useful but still visible to software as an extra register).
However according to the 2553 datasheet, the 28 pin package option does bring P3 out as 8 pins.