Are the logic inputs TTL or CMOS? Could not find on this page:

http://mbed.org/handbook/mbed-NXP-LPC1768

It is confusing because the following page describes both cases but does not say which the MBED actually is.

http://mbed.org/users/4180_1/notebook/pushbuttons/

I need complete specs including low state threshold voltage. Thanks.

I think I have an answer but I STILL would like someone to do a sanity check on this (please). The attached is from the LPC1768 data sheet and it appears the "Standard ports" are TTL.

High-level input voltage must be greater than 2.0 V

Low-level input voltage must be less than 0.8 V

This assumes the ports on the LPC1768 go directly to the MBED pins. Is the above valid for all of the "blue" MBED pins (5 - 30)?

/media/uploads/Kramer/digital_pins.jpg

I don't know which special information do you need, but on the page you linked there is a sentence

Which means they are NOT TTL.

The digital ports are not TTL as Rene points out, but they are TTL compatible. That means the high-level out (3V3) is above the minimum input voltage of 2.0V that a TTL device expects. The low-level out is below the 0.8V level that a TTL device expects.

The mbed DigitalIn is TTL compatible because it sees the correct high and low levels that TTL devices provide. Note that the crucial point is that the lpc1768 can tolerate the 5V high levels on its inputs !

Just: the mbed pins 5-30 go directly to lpc1768 pins. You can check that in the schematic. http://mbed.org/media/uploads/chris/mbed-005.1.pdf

The Link is on http://mbed.org/handbook/mbed-NXP-LPC1768

Good analysis of the logic specs, appreciate the help. If you don't mind, I would like to state my opinion that a user shouldn't have to look in the forums to get this information. Whether a user is interfacing with linear ICs such as comparators or using discrete devices or diode logic, or simply wants to see what his noise margins are with traditional logic, these specifications are important and should be easy to find. It certainly should not require looking at the schematic and going to the LPC1768 specifications as we had to do. Just guessing, I would say the reason these specs don't appear on the pinout page is that the original engineer probably didn't know, but now we do! Every logic IC in the world has this information (really), so I suggest the good people at MBED add at least the basic I/O specs shown below to the pinout page.

By the way, the 40 mA spec is not exactly correct either. Please see the following new topic.

http://mbed.org/forum/bugs-suggestions/topic/3364/

MBED rocks, and I hope this helps.

Recommended wording of logic levels:

Digital IO: 
Input low state requires <= 0.8 V 
Input high state requires >= 2.0 V 
Input will tolerate up to 5 V high state
Output high state is >= 2.9 V with 4 mA current out of pin
Output low state is <= 0.4 V with 4 mA current into pin
Output short circuit limited to 40 mA (maximum 400 mA total)