Hi,
I have a problem with my Arduino. When I plug it to a certain chip (ADXL345) as pointed out in the datasheet the Arduino IDE Tool>Serial Ports menu is automatically grayed out.
After some experimenting I discovered that grounding the arduino 3v out (I assume it's not a healthy thing to do?) also makes it disappear. Disconnecting either the power or the ground when the chip is connected gets the Arduino back in the menu also. So basically I have two questions:
Is the arduino behavior something you'd expect?
Is the chip broken?
Edit: When I break the circuit (disconnect either ground or 3v) TX/RX both blink rapidly for about half a second
Sounds like your chip (ADXL345) or wiring to it from the Arduino is causing a short circuit condition. That could activate the 500ma thermal fuse or fail the on board USB FTDI chip on the Arduino board to fail, causing your PC to think the USB port is unplugged so it removes the USB comm port.
Make sense?
PS: Keep in mind also that the on board 3.3v pin can only supply around 30ma of current and if you draw too much that might cause the same problem/symptom.
Lefty
In general it does makes sense. How do I check if the chip is problematic, and if it is, how is it causing the problem (ie shorting or drawing too much)?
And I'll repeat my first question (couldn't infer the answer from your reply) is that normal Arduino behavior to disappear when shorted?
Thanks
