Adding a stepper motor to the binary scale to indicate when there is weight on it
Learned:
- How to talk between 2 microcontrollers
- That stepper motors create a lot of noise in a circuit when they are operating
- How a stepper motor works internally
I wanted to add a flag that would raise up when the scale detected weight and lower when the weight was
removed. This involved adding a second processor because a stepper motor requires 6 pins and the binary
scale required 2. The layout of the board is below. Essentially I combined the sample stepper motor circuit
with my scale circuit. The communication between the two microcontrollers is via one pin between the two. The
pin is set high to indicate the scale had weight and low when there was no weight. The stepper circuit would read an A/D
and raise the flag depending on the read value. The problem that I ran into was that when the stepper was operating it
would create a massive amount of noise via the power supplied to the microcontrollers and make getting a nice clean step
reading impossible. Here is a picture of the new setup.
Here are the files relevant to the stepper and scale circuit: