Switching between sketches/projects

Using Arduino General Electronics
#1

Likely a rookie question here....

I've been tinkering with the Stepper and LCD tutorials today. Some of the scripts use the same pins to drive the motor or LCD. As I switch between projects/sketches, I'll unplug the Arduino USB, pull the LCD circuit pin wires out, and hookup for the Stepper project on the pins/breadboard. However, when I plug the USB back in, it will still have the LCD sketch on it until I can upload the other Stepper sketch. Makes sense?!?

I can easily imagine a scenario where the Arduino is anticipating an OUTPUT but gets input from some component on the breadboard. Is there a risk to components or the Arduino itself with the sketch vs circuit mismatch?

#2

Risk, Yes.

Suggest you upload new sketch before hooking up the new connections.

#3

Yes, there is the potential for damage due to sketch-vs-circuit mismatch. It's unlikely with an LCD shield and motor driver since they would both tend to receive signals from the Arduino, which might lead to a brief period of confusing behavior, but no damage. Worse would be if a shield had an output pin (input to the Arduino), and the sketch configured that pin as an output as well.

If you are disciplined, you can upload a "dummy sketch" into the Arduino whenever you switch shields:

setup() {} loop() {}

-- The Ruggeduino: compatible with Arduino UNO, 24V operation, all I/O's fused and protected

#4

Thanks for the super fast replies. I like both of those strategies.

For others following this thread in the future, the dummy sketch needs to be this (added the VOID keywords):

// Dummy sketch to avoid any sketch vs circuit mismatch.  
// Use to protect your arduino when switching projects

void setup() {} 
void loop() {}
#5

The Ruggeduino: compatible with Arduino UNO, 24V operation, all I/O's fused and protected

Excellent product! Like it 8)

#6

Or just untach the wires, upload, unplug then wire new

#7