drkm

When a GPIO in an input state the input is high impedance. Meaning that there is a large resistance between the any voltage that could be present on the pin and the GND/0V. Since V=IR, if R is high then we can guarantee that the current will be low. 
 
Pulling the pin low with a pull down resistor provides a path to ground (while maintaining a large input impedance) that any stray EMI from say an ossilator or power supply.
 
When a GPIO is set to an output it is either sinking or sourcing current. Meaning that if you were to pull the line low you are allowing the current path to go through the processor through the pin. ( I am simplifying this a fair bit since there are protection diodes, ect).
 
Does that make this clearer? Like I said earlier, the enviroment has alot to do with these variables as well. If you were working on a small board that had a ossilator ossilating at high frequencies, EMI becomes an issue.
 
For the RX pins that you are disconnecting, ect. I would leave the pins in high impedance such that if you had an accident or misplaced wire the risk of destroying something goes down significantly since there is no "easy" path to ground. 

Nice job!

I heard about this a few weeks ago from our AVNET sales guy. Its super exciting!
 
Apparently the automotive guys are going nuts over it since they can now get high resolution data with simple/cheap components without having to worry about hi-temp components. Think ABS, brake sensors, sensors closer to the combustion chamber, ect.
 
Even for motor control/robotics applications this is huge, especially the resolution you get out of this thing!

I heard about this a few weeks ago from our AVNET sales guy. Its super exciting!
 
Apparently the automotive guys are going nuts over it since they can now get high resolution data with simple/cheap components without having to worry about hi-temp components. Think ABS, brake sensors, sensors closer to the combustion chamber, ect.
 
Even for motor control/robotics applications this is huge, especially the resolution you get out of this thing!

I heard about this a few weeks ago from our AVNET sales guy. Its super exciting!
 
Apparently the automotive guys are going nuts over it since they can now get high resolution data with simple/cheap components without having to worry about hi-temp components. Think ABS, brake sensors, sensors closer to the combustion chamber, ect.
 
Even for motor control/robotics applications this is huge, especially the resolution you get out of this thing!

I love the m3, but I have to use the C28x line for speed. I was really excited about the LM4F (with floating point accelerorator!!!)
 
Now go and check attached image. Prepare for mind explosions...

I love the m3, but I have to use the C28x line for speed. I was really excited about the LM4F (with floating point accelerorator!!!)
 
Now go and check attached image. Prepare for mind explosions...