Stepping motor control device capable of reducing load on CPU

摘要

A stepping motor control device comprises a plurality of buffers for storing data for driving a stepping motor, a read unit for reading the data from the buffer, and a write unit for writing the data in the buffer. The write unit includes a first mode for writing the data in the buffer in a process performed in a predetermined order, and a second mode for writing the data in the buffer in response to a request from the read unit to write the data.

主权项

1. A stepping motor control device included in an image forming apparatus comprising:
a CPU for performing a steady process normally including a series of processes regarding an image formation in the image forming apparatus in predetermined order and performing an interrupt process when said CPU receives a request for said interrupt process; a ring buffer having a plurality of buffers for storing pulse data, which contains a pulse width of a pulse to be outputted and the number of outputs of the pulse having the pulse width, for driving a stepping motor; and a read unit for reading pulse data from said ring buffer and outputting a pulse to a motor drive unit for driving said stepping motor based on the read pulse data; wherein said CPU determines, from a buffer designated by a write position register to the buffer preceding the buffer designated by a read position register along a predetermined circular moving direction of said write and read position registers among said plurality of buffers as a buffer in which pulse data can be written, in said steady process; and said CPU writes pulse data in said determined buffer when said CPU determines there is a buffer in which pulse data can be written and performs the series of processes regarding the image formation when said CPU determines there is no buffer in which pulse data can be written, in said steady process, and writes pulse data in all the plurality of buffers in said interrupt process when said CPU receives said request for said interrupt process; wherein said read unit determines from a buffer designated by the read position register to the buffer preceding the buffer designated by the write position register along said predetermined circular moving direction among said plurality of buffers as a buffer from which pulse data can be read, while said steady process is performed by said CPU; and said read unit reads pulse data from the determined buffer when said read unit determines there is a buffer from which pulse data can be read, and outputs said request for said interrupt process to said CPU when said read unit determines there is no buffer from which pulse data can be read.