SparkFun Forums

[jgarbers]

I realize that pins 0 and 1 are special on Arduino, as they're used for serial communication. However, it appears that they can also be used as digital outputs. If I don't intend to use Serial.begin in my sketch, can I connect LilyPad MicroLEDs to pins 0 and 1, and work with them the same as the other pins? Would doing that interfere with my ability to connect the FTDI interface for uploading sketches? Thanks in advance for any advice on this!

[TS-Liz]

Those pins can indeed be used as digital output pins. If you are not using them for serial communication, then they can be used for digital outputs. However, uploading code via the FTDI uses those two serial pins as well. At the minimum, any extra things (LEDS, motors, etc.) connected to those two pins will pulse or blink while you are uploading the code. Depending on the exact setup, the connected extras can even prevent a successful code upload. Unexpected behavior is likely.

If you are running out of pins and you happen to be using a LilyPad Arduino Simple (https://www.sparkfun.com/products/10274), you may consider moving to the LilyPad Arduino 328 Main Board (https://www.sparkfun.com/products/9266), which has more pins available.