I would assume the digital I/O pins operate at 5V (so as to interface with most ICs). Is this correct? I need to know so I can calculate resistor values for LEDs on these pins.
Yes that is correct when a pin is high, it is approx. 5 V
The I/O pins output a high voltage about equal to the supply voltage wired to the processor chip. Most common Arduino boards use +5vdc, but some small breadboard/stamp module models use 3.3vdc.
I ordered a Duemillanove, so I'm assuming then it will be about 5V. This is good. Now that I've calculated the resistance needed for my LEDs, I can place my component order (about 80 bucks worth of toys ;D)
I can place my component order (about 80 bucks worth of toys)
You will realise once you get into arduino that $80 of stuff is not that much and you always want something else :D
I have purchased more than $300 of stuff or something like that in the half a year that i've been doing arduino stuff. I have also used a lot of second hand (free stuff) in projects, so make sure that if you see something, you take it because you will want a big bits box to take things from for future projects ;)
Anyway, hope you enjoy arduino. Out of interest, what stuff have you purchased?
LEDs, caps, pots, resistors, dip switches, 555 timers, off-mom switches, 4051's, and some terminal strips. I also picked up a few items for PCB etching (I'll probably build a UV LED box for photoresist in the next week or so). My interest in electronics isn't Arduino specific, but coming from a computer science background, it's nice for circuits involving logic (sure beats boolean algebra and a bunch of NAND gates).
sure beats boolean algebra and a bunch of NAND gates
I would assume the digital I/O pins operate at 5V
Or 4.75 volts when its hooked up to my computers USB…
The data sheet says that if the chip is being powered by 5V and is supplying 20mA then the minimum high level output voltage is 4.2V.