So I was recently having a bunch of trouble with a Sparkfun XBEE shield... No surprise here. Attempting to program this device over the XBEE, or communicate with it AT ALL!
Upon hooking the oscilloscope to the serial lines, I noticed that it was never able to pull the line below... say 2 volts, but it was doing it fine on the Leonardo. Wasn't' that weird.... but then I realized that there are 1K resistors on pins 0 and 1... and ONLY on the pro. Needless to say, the 1K resistors on the level shifter circuit on the shield (which should have been 10K or more) was playing voltage divider with the 1K on the Arduino Pro. So clearly this is a problem with the Sparkfun board, but my question is this..
WHY does the Arduino Pro have 1K resistors on the TX and RX lines? (and not any other arduino including the Pro Mini?)
Am I missing something? Will I regret putting jumpers over these resistors in my project?