Automatic coil winder and 18F4550 PIC microcontroller based control unit and Linistepper drivers.

This is the 2nd version of my Microchip PIC based Automatic Coil Winder Control Unit. It is based on the PIC18F4550 microcontroller.

The controller has more flash memory to expand and improve the winder program. A faster microcontroller, 12 MIPS versus 5 MIPS. An updated board layout to better access to the microcontroller's built in features.

The controller outputs are now compatible with readily available stepper motor driver boards such as the LiniStepper driver for unipolar stepper motors that I paired the controller with.


Top view of PIC18F4550 based coil winder control unit.

You can check out my previous PIC16F887 / PIC16F886 based coil winder control unit that this unit replaces.

I migrated my main winder program from the PIC16F887 microcontroller to the new PIC18F4550. At this point the program information from my first pic based main winder program is valid for this winder.

Although, I did add a microsecond main loop step delay adjustment. This is in addition to the existing millisecond adjustment.


Inside view of PIC18F4550 based coil winder control unit.

Under the hood of the automatic coil winder control unit you can see the 40 pin 18F4550 microcontroller used to run the coil winder program.

I have a 3 pin header strip for the RX, TX and a ground pin of the microcontroller for serial reprogramming and a button to reset the microcontroller.

For possible future use I have a 3 pin header strip for I2C communications and lands in place and holes drilled for a USB connector.

The blue trimmer potentiometer is for adjusting the lcd display contrast. I set the lcd backlight brightness with a 330 ohm resistor.


Coil Winder board layout printed on toner transfer material. Etched and drilled PIC18F4550 based coil winder controller circuit board.

For the new controller board I drew the schematic diagram and board layout using KiCad open source software. This was the first time I used KiCad and I really like the software.

When it came time to print out the board layout, I was happy to see that it printed out to scale, but disappointed to find that I had no control to position the layout on the paper, which would have resulted in wasting a full sheet of paper or toner transfer material to print one copy of the layout. I ended up doing a screen capture of the print preview and pasting the image into Paint Shop Pro so I could have control over the printout. This was important because toner transfer material is not inexpensive and I didn't have any full sheets left.


Populated coil winder 18F4550 based controller board.

Here is the populated PIC18F4550 based coil winder board.



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