My home-built Automatic Coil winder and PIC microcontroller based control unit.

My Microchip PIC based Automatic Coil Winder Control Unit is the latest addition to the coil winder eliminating the need for a pc with a parallel port to run the coil winder. Since I already built the stepper motor driver board this control unit interfaces directly with the original automatic coil winder driver board.

This microcontroller based control unit offers more precise control over the winding process than the original pc based coil winder program.

To use the winder you input the values needed by depressing the push buttons located at the bottom of the lcd display while stepping through the menus. One of the menus allows you to jog the carriage into position before starting the winding process.

Top view of coil winder control unit.

When you get to the last menu you have a choice to loop through the menus again or start the coil winder.

When the winding is complete the control unit will play a few musical notes to let you know the coil is done and you will be prompted to park the carriage and return to the start menu or just return to the start menu.

The winder can also be paused during a run, then you can continue the run where it left off or abort the run and you have the option to park the carriage.

Rear view of winder control unit.

When I took the photos for this web page I was running the main winder program on a PIC16F877A microcontroller and the step motor sequencing program on a PIC16F876A.

I am now using the newer PIC16F887 and PIC16F886 microcontrollers.

Inside view of winder control unit.

Under the hood of the automatic coil winder control unit you can see the 40 pin 16F877A microcontroller running the main winder program and the 28 pin 16F876A microcontroller running the motor step sequencing program.

I have header pins in place for the RX and TX pins of the microcontrollers for serial reprogramming and buttons to reset each of the microcontrollers.

The first of the four dip switches is used to select standard stepping mode or wave step. The second switch is used to select half step mode. The other two dip switches are currently unused. The blue trimmer potentiometer is for adjusting the lcd display contrast. I set the lcd backlight brightness with a 330 ohm resistor.

Etched on drilled circuit boards for coil winder control unit.

I laid out the circuit boards with Paint Shop Pro X. I normally layout boards with Eagle Layout but I did not want to spend the extra time it would have taken to do the layout.

I printed the layout with my laser printer onto a special transfer material and used a clothes iron to transfer the toner to the circuit board.

I always create the circuit layout images over-sized and scale them to size in the print dialog box on the computer when I am printing them out. If I have an IC in the layout I use ic pin spacing to get the image scaling correct. I have found I get better results using this scaling method.

PIC based coil winder stepper motor driver board.

My revamped motor driver board with two sets of header pins to connect the control unit driver outputs to the driver board inputs.

Circuit board layout printed on paper to check component layout.

After laying out the circuit board on the computer, I printed the layout on paper, laid the paper on foam and inserted the components to check and adjust the layout.

When I finished etching and drilling the circuit boards I already had all the resistor and jumper leads formed so I could just move them over to the circuit board(s).

PIC based coil winder control unit built on breadbread for testing.

After laying out the circuit board and redrawing the schematic diagram to reflect programming changes to the i/o pin functions, I created the cleaned up breadboard version of the winder controller.

I have since dismantled the breadboard version and just work with my pcb version of the winder control unit.

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