Looking through the datasheet there's a set of graphs that looks like what I want on page 25. I'm a bit confused as to what they mean.
For example, let's focus on the two graphs on the right which correspond to Vcc = 3v. I think the top graph is what would happen if you try to sink current with P1.7 and the bottom graph is what would happen when you try to source current with P1.7. I'm not entirely sure what these graphs are saying, though. Why would the pin voltage change? I thought the device was supposed to hold the pin voltages steady at 0v or Vcc when you output low and high respectively. Additionally, I can't seem to find a maximum sum current rating for all of the pins.
The project I'm trying to do specifically is to light groups of LEDs using multiple pins like this. This is my first attempt at using a micro controller outside of class and I'm rather new at this, so any help would be appreciated!