Abstract: A system for controlling a stepper motor is disclosed that includes a microprocessor for directly generating current command signals. The microprocessor has a memory wherein the memory includes a function table, a first function table address, and a second function table address. A velocity signal (indicating a rotational position change per unit time) is calculated by the microprocessor during each update interval. Each update interval comprises a plurality of interrupt intervals. The microprocessor, in accordance with software-selectable current magnitude parameter values and microstepping parameter values, determines a first and second current value by accessing the function table at the first and second function table addresses, during each interrupt interval. The first and second current values generated by the microprocessor correspond to a pair of digital words representing a pair of phase current commands.

Abstract: A system for controlling a stepper motor is disclosed that includes a microprocessor for directly generating current command signals. The microprocessor is of the type having memory wherein the memory includes two transfer tables. The microprocessor, in accordance with software-selectable current magnitude parameter values and microstepping parameter values, determines a sequence of digital words to populate a first one of the tables. The stepper motor is a two-phase motor and the digital words correspond to the phase current commands are generated by the microprocessor using sine, and cosine law function tables. A DMA (Direct Memory Access) controller in the microprocessor outputs the populated transfer table to a drive circuit to energize the stepper motor while the main control software executing in the microprocessor populates the second-transfer table. Once the first transfer table has been completely output to the drive circuit, the roles of the transfer tables are reversed and the process is repeated.