Stepper motor PWM controller with single fiber optic input.1. The single fiber optic input, provide a complete electric insulation between the PC and the laser engraver. => Finished product (Work as expected)īoards with XC95144XL CPLD, implementing bidirectionnal linkįinished jan/24/2014 work as expected ApplicationĪn application : A replacement card for a laser engraver (model K40), with stepper motor driver. Serial to parallel and Parallel to serial fiber optic PCB module including 5V to 3.3V IO buffer. PLR/PLT133-T7 Everlight electronic fiber optic modulesĪudio (SPDIF) fiber optic cable Perspective XC9572XL Xilinx CPLD (1 for transmitter + 1 for receiver) The deserializer will compare the number of step of each frame with the previous frame and allow/disallow a pulse on the corresponding output.įortunately the serializer OR deserializer fit into a single XC9572XL CPLD. The Serializer transmit the number of step (modulo 2) + the DIR value on the most recent step edge. The serializer, in that case incorporate a 1-bit step counter and a dir latch. The STEP and DIR signals cannot be transmitted on the serial link like normal control signals, because they are registered pulse signals. At each step edge, the controller sample the DIR signal and advance motor in the direction of DIR. The controller count rising edges of the STEP signal. Lets explain how a CNC stepper motor controller works I will talk more about that in the next paragraph. It is ok also for variable signals in the range 1000-3000Hz like PWM speed control.īut it is not enough for stepper motor control signals (STEP and DIR). are transmitted each second and this update frequency is ok for normal digital signals like clear, enable, relay control. The receiver can easily detect the frame delimiter pattern as well as each bit '0' or '1' of the frame.Ģ00.000 frames approx. The frame delimiter is 1.5 bit duration and is the overhead that add to payload of each frame.

Stepper motor signals (STEP and DIR) of each of 4 axis X,Y,Z,A The function of the control signals are either : Parallel port SUBD-25 pin with controls (s0-s11), input (i0,i4)

This is the close view of the data wire (white color). The FPGA device serialize the control signals from the parallel port, transport the data through a single wire, then deserialize the data at arrival. I would like to show you how I control my CNC equipment (which is usually controlled by a PC parallel port) with a single wire using a special FPGA device. Moreover, the data wire is intended to be a fiber optic in the final form of the project. It can transport all signals of the PC parallel port into a single wire.

A device that convert a PC parallel port to serial, then serial to parallel.

Parallel to serial converter buffer