Programmable stepper motor controller

Claim 1

A method for controlling current through a motor winding, comprising the steps of: sensing a current level through the motor winding; switching a winding current supply off for a selected first time period when a sensed winding current level reaches a preselected level; after the first time period, switching the current supply on; also after the first time period, inhibiting said sensing step for a selected second time period so that said switching the supply off step cannot occur, wherein said sensing step is resumed after the second time period expires; and continuously repeating said sensing, switching and inhibiting steps.

Claim 2

A method for controlling current through a motor winding, comprising the steps of: sensing a current level through the motor winding; switching a winding current supply off for a selected first time period when a sensed winding current level reaches a preselected level; after the first time period, switching the current supply on; also after the first time period, inhibiting said sensing step for a selected second time period so that said switching the supply off step cannot occur, wherein said sensing step is resumed after the second time period expires; and continuously repeating said sensing, switching and inhibiting steps.

Claim 3

A method for controlling current through a motor winding, comprising the steps of: sensing a current level through the motor winding; switching a winding current supply off for a selected first time period when the winding current level reaches a preselected level; after the first time period, switching the current supply on for at least a selected second minimum time period; continuously repeating said sensing and switching steps; and upon receipt of a control signal indicating that operation should occur in a detent mode, forcing an indicator of sensed current level to a state which indicates that the winding current level is higher than the preselected level regardless of its actual value, whereby a next switching off step occurs immediately after each switching on step is completed.

Claim 4

A method for controlling current through a motor winding, comprising the steps of: sensing a current level through the motor winding; switching a winding current supply off for a selected first time period when the winding current level reaches a preselected level; after the first time period, switching the current supply on for at least a selected second minimum time period; continuously repeating said sensing and switching steps; and upon receipt of a control signal indicating that operation should occur in a detent mode, forcing an indicator of sensed current level to a state which indicates that the winding current level is higher than the preselected level regardless of its actual value, whereby a next switching off step occurs immediately after each switching on step is completed.

Claim 6

A system for controlling current through a motor winding, comprising: a sensor for sensing current flow through the winding; a comparator connected to said sensor for generating a first signal which indicates whether the current flow through the winding is greater than a preselected level; a timer for measuring first and second time periods of a preselected length; a control circuit connected to said timer and said comparator for, when the first signal is generated, generating a second signal for the first time period followed by a third signal for at least the second time period; means for switching a current supply to the motor winding in response to the second and third signals, wherein the supply is switched off when the second signal is generated and switched on when the third signal is generated; and means for selectably forcing the first signal to a level indicating that the current flow through the winding is greater than the preselected level regardless of its actual level, whereby said control circuit again generates the second control signal immediately after the second time period is completed.

Claim 7

A system for controlling current through a motor winding, comprising: a sensor for sensing current flow through the winding; a comparator connected to said sensor for generating a first signal which indicates whether the current flow through the winding is greater than a preselected level; a timer for measuring first and second time periods of a preselected length; a control circuit connected to said timer and said comparator for, when the first signal is generated, generating a second signal for the first time period followed by a third signal for at least the second time period; means for switching a current supply to the motor winding in response to the second and third signals, wherein the supply is switched off when the second signal is generated and switched on when the third signal is generated; and means for selectably forcing the first signal to a level indicating that the current flow through the winding is greater than the preselected level regardless of its actual level, whereby said control circuit again generates the second control signal immediately after the second time period is completed.

Claim 8

A system for controlling current through a motor winding, comprising: a sensor for sensing current flow through the winding; a comparator connected to said sensor for generating a first signal which indicates whether the current flow through the winding is greater than a preselected level; first and second registers for retaining values corresponding to first and second time periods; a timer for measuring the first and second time periods of a preselected length; a control circuit connected to said timer and said comparator for, when the first signal is generated, generating a second signal for the first time period followed by a third signal for at least the second time period; and means for switching a current supply to the motor winding in response to the second and third signals, wherein the supply is switched off when the second signal is generated and switched on when the third signal is generated.

Claim 9

A system for controlling current through a motor winding, comprising: a sensor for sensing current flow through the winding; a comparator connected to said sensor for generating a first signal which indicates whether the current flow through the winding is greater than a preselected level; first and second registers for retaining values corresponding to first and second time periods; a timer for measuring the first and second time periods of a preselected length; a control circuit connected to said timer and said comparator for, when the first signal is generated, generating a second signal for the first time period followed by a third signal for at least the second time period; and means for switching a current supply to the motor winding in response to the second and third signals, wherein the supply is switched off when the second signal is generated and switched on when the third signal is generated.

Claim 12

A system for generating a control signal, comprising: a counter; first and second registers selectively connected to a preload input of said counter; a memory element; a register selector for selecting one of said registers to be connected to the preload input; an input signal having at least first and second states; and logic means for, when said input signal is in the first state, loading a first value from said first register into said counter, causing said counter to count from the loaded value to zero, and setting said memory element to a first state, and for, when said counter has reached zero, setting said memory element to the second state, loading a second value from said second register into said counter, and causing said counter to count from the second value to zero, wherein the state of said input signal is ignored until after said counter has counted to zero from the second value.

Claim 13

A system for generating a control signal, comprising: a counter; first and second registers selectively connected to a preload input of said counter; a memory element; a register selector for selecting one of said registers to be connected to the preload input; an input signal having at least first and second states; and logic means for, when said input signal is in the first state, loading a first value from said first register into said counter, causing said counter to count from the loaded value to zero, and setting said memory element to a first state, and for, when said counter has reached zero, setting said memory element to the second state, loading a second value from said second register into said counter, and causing said counter to count from the second value to zero, wherein the state of said input signal is ignored until after said counter has counted to zero from the second value.