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BPSSTEP Stepper driver hardware and software for PC

Four axes micro step driver/controller. Switching power supply for micro step control. One turn is divided into 1600 positions with 50 pole stepper. All software is written in assembly language (real-time 8086/88, 80286 or 80486). All hardware designed by same author (L298 based drivers).

Hardware is divided into two parts:

  1. Driver - output stage for coils; synchronized switching regulation of coil current. Each coil driver has three inputs: output enable (digital), output polarity (digital) and desired coil current (analog). Also, in order to enable synchronization, there is clock input. The L298 IC is used as output stage.
  2. Interface card - PC controls steppers through interface card. I made that interface as ISA bus card. It is possible to make that interface to be connected to PC via parallel port. Each stepper I've implemented uses two analog (four bit) and four digital outputs, so, this interface adapter has eight analog (four bit) outputs and sixteen digital (TTL) outputs.

Software is little bit complicated:

  1. Real time TSR driver. By hooking INT0 it is solved real time controlling. System timer is 1024 times faster than standard BIOS timer thus enabling time base of ~50 microseconds. Standard BIOS INT0 service routine is kept at standard speed (55ms). This driver works fine under DOS, but because of low level access to system resources it is not possible to implement under Windows 95.
  2. BIOS extensions. To allow application to access TSR modules, BIOS service 14h is extended (COM port services). All TSR modules are written in assembly language.

I made this for use in analytical stereo comparator which is property of Geodetski Zavod dd Rijeka (Croatia), but this can be used in different projects: NC tool machines, robots, etc.

Detail of output stage