DMA Fab Lab Encoder/Stepper demo project

Parts list:

• Arduino Leonardo - Could be anything, we used what we had around
• Stepper motor - NEMA-17 size - 200 steps/rev, 12V 350mA
• Encoder - Yumo E6B2-CWZ3E
• 2 X Pololu Universal Aluminum Mounting Hub for 5mm Shaft
• Nylon spacers for PCBs
• 3 x 3 mm magnet
• Reed switch
• Female Threaded Hex Standoff, 13mm Hex, 52mm Long, M6 x 1mm Thread - Any spacer longer than 1.75" will do
• 4 X 3 mm LEDs
• 12mm Momentary Push Button Switch 1/2" Mounting Hole - We're using these ones but any momentary switch will do
• 12 V DC power supply - Something like this should do
• DRV8880 Stepper Motor Driver
• Jumper wires or ribbon cable - we're using ribbon cable with crimpable connectors
• 40 x 60 mm perfboard
• 4 X 470 Ω resistors
• 22AWG Solid core wire
• Assorted screws and nuts for mounting parts

Code:

• Use the EncoderProject_06 arduino sketch from the Code folder
• This project uses two libraries: the Encoder library and the StepperDriver library
• Code is a bit messy and not very commented for now

Fabrication:

• This project requires some laser cutting. There are two files in the Fabrication folder:
  • Electronics plate laser cut.ai
  • Main plate laser cut.ai.
  • Both files contain instructions for materials
• There are two optional 3D printed parts. Both can be found in the Fabrication folder:
  • CableGuide v3 is a small cable routing part that can help managing the wires
  • Reed Switch Holder v2 supports the reed switch at the correct rotation relative to the magnet

How it works:

• Once plugged in, the stepper motor will turn until it finds the "home" position (3 o'clock)
• From there, you rotate the encoder arm by hand until it matches the 3 o'clock position
• Now you can turn the encoder arm and the stepper motor will follow
• If both arms get misaligned, you can press the "Reset" button, that will make the stepper search for its home position again
• If you spin the encoder arm too quickly, the stepper will stop, the "Mode/State" LED will blink and the the stepper will search for its home position again

Documentation images and video can be found in the Photos folder.