Stepper driver

3-axis-controller

A manipulator device to operate microscope stage XYZ translations. This project was specifically designed for the OpenFlexure Delta Stage.

Assembly

Assembling the Board

1. Order the (2 layer) board from a PCB manufacturer (e.g. JLCPCB) by uploading this file.
2. Using the BOM, solder together the integrated board from electronics/integrated_board. The board is labeled with the locations and values of resistors, capacitors etc.
   • Make sure to solder socket headers to the board and slot in the esp32 and pcf8575 modules rather than soldering them directly to the board. Sometimes things go wrong and they will be very hard to remove...
   • All parts are intended to be soldered as sitting on the top face of the board - any differences seen in the 3D view of the PCB in KiCAD should be ignored

Software

Setting up MicroPython with Thonny IDE

1. Follow the tutorial on this page if you haven't already done so when assembling the board.

Upload the Code

1. Download the code here
2. Open them all in Thonny.
   • Connect your board to your PC via micro USB.
3. In Thonny, in the files panel (view > files) navigate to the location of the code to be installed
4. Highlight all files and folders, including lib
5. Right click and select Upload to /
6. CHECK: Does the file layout in the esp32 look like that on this GitHub?

Assembling the controller

1. Assemble the JST-XH cables mentioned in the BOM
2. For each button and flip switch, cut one crimped wire in half and solder before attaching to the JST-XH head Orientation doesn't matter.
   
3. Print the enclosure top and assemble as shown. Include the other rotary encoders and switches (not shown). The appropriate washers and nuts to screw onto the front face should be shipped with each component. Use M3x10 screws for the LCD.
4. Use a 4-pin JST cable to connect the LCD to the marked port. Make sure the GND and VCC pins are attached to the same connection on the main and LCD board.
   • NOTE: there is a variable resistor on the back of the LCD board that adjusts the contrast, so don't screw the whole box shut until you've tested the text appears correctly
5. Use a 5-pin JST cable for each rotary encoder. MAKE SURE the GND pin connects to the pin marked with "-" on the encoder.
6. Plug in all the switches to the board to their closest port.
   • DO NOT PLUG SWITCHES INTO THE PORTS MARKED AS 12V/GND AS IT MAY START A FIRE AND SOME FEATURES MAY NOT WORK AS INTENDED
7. Once you are confident the LCD is displaying text correctly when powered on, assemble the enclosure as shown. Make sure to print the feet in some TPU for grip. Use M3x16 (or longer).

• Note you should have all components wired up and screwed in at this point, not all of this is shown on the diagram.

  

Connecting to the Delta Stage

1. Split the length (2M) of ribbon cable at the ends into 3 strips of 5 wires, and 3 strips of 2 wires. You can peel away the remaining wires and discard them.
   • Note it may be helpful for cable management not to entirely separate the 3x5 and 3x2 strips.
2. Crimp one end of the cable, and slot into JST XH 5 or 2 cable headers respectively.
3. Put a short length of heat-shrink tubing on each remaining end of all wires.
4. Next, solder the remaining 3x5 wires to straight JST HX 5 pin headers (male)
   • Ensure the orientation of both ends of the cable is such that each lane could form a complete loop if it were plugged into itself without any twist. (i.e. each in and out pin is the same)
5. Solder the sets of 2 wires to the footswitches - one to the middle-pin, the other to the pin towards the hinge of the lever.
   • Ensure this configuration is such that a circuit is made (not broken) when the switch is pressed
6. Use hot air or a soldering iron to shrink the heat-shrink tubing and cover these solder joints.
7. Use m2x8 screws to attach the switches to the modified feet of the Delta Stage and use these in place of the ones on the official models when assembling the actuators
   • Make sure to use the modified models found here for the open 2-photon project

Installing the I2C library

You may need to install the lib portion of the I2C code another way - the above method should work, so only follow these instructions if something is not behaving as expected.

1. Download micropython-i2c-lcd-0.1.1.tar.gz
2. In Thonny go to Tools > Manage Packages
   • make sure the esp32 is still plugged in to your computer
3. Click the Install from local file link and select the .tar.gz file you downloaded
4. CHECK: Does the file layout in the esp32 look like that on this GitHub? You should not need to but you may have to rename the folder to ensure all the code is looking in the right place...