I have a 2 dof hexapod, and to control it ive gone low-fi, and just used an arduino mega with a sensor shield. The shield has a power selector, so you can either power it via your arduino or an external battery. When the jumpers are jumped it feeds off the arduino, and when they're not it draws from the battery. When I power it from the battery, however, it shuts down my laptop, and on my pc the com port dissapears. Any idea what would cause this?
This would be a DIRECT SHORT somewhere in your circuit.
Best would be to trace the positive and negative rails with a multimeter to find them and double check they are correct (doubtful)
Bob.
I checked it all over, then i realized i had another one, so i hooked that up the same way and now when i upload (the com port shows), it gets past compiling, and gets stuck on "uploading..." heres my error code
Arduino: 1.8.7 (Windows 7), Board: "Arduino/Genuino Mega or Mega 2560, ATmega2560 (Mega 2560)"
Sketch uses 3432 bytes (1%) of program storage space. Maximum is 253952 bytes.
Global variables use 194 bytes (2%) of dynamic memory, leaving 7998 bytes for local variables. Maximum is 8192 bytes.
avrdude: stk500v2_ReceiveMessage(): timeout
avrdude: stk500v2_ReceiveMessage(): timeout
avrdude: stk500v2_ReceiveMessage(): timeout
avrdude: stk500v2_ReceiveMessage(): timeout
avrdude: stk500v2_ReceiveMessage(): timeout
avrdude: stk500v2_ReceiveMessage(): timeout
avrdude: stk500v2_getsync(): timeout communicating with programmer
An error occurred while uploading the sketch
This report would have more information with
"Show verbose output during compilation"
option enabled in File -> Preferences.
By any chance are you using pin 0 and 1 ?
If so disconnect whatever is using them.
Bob.