raspi cannot read USB serial

I have an arduino running Serial.println and I never get the output on my raspberry pi when it is connected. It does create the device in /dev and looks like it should work but I never get any output. I whittled down my arduino program to the point where it literally did nothing but hello world once a second, and I still never see the output. Using my PC and the arduino IDE, serial monitor shows the output I am looking for.

What gives? I swear this worked six months ago, too. Maybe kernel/raspbian changes getting in my way?

Oh, I should note that I am trying to read with both sudo cat and sudo tail -f on /dev/ttyACM0 , which is definitely my arduino device

No dice on my buddies powerbook either!

what is the voltage level of the raspi? 3.3V or 5.0V ? The Arduino is 5.

Oh, good idea, but these are plugged in via a powered hub so I made sure they still got full 5V. plus when I had sensors/LED attached they still behaved as expected, it is only the serial that I am failing to get

Can you run puTTY on the RPi?

...R

The problem is with the code on your Raspberry Pi.

/dev/ttyACM0 , which is definitely my arduino device

How do you know? I found that the Arduino could also show up on /dev/ttyACM1 as well almost at random.

I am trying to read with both sudo cat and sudo tail -f

Sorry that is Linux gobbledegook, have you tried reading it from a python sketch?