Marquette Hellige GmbH
MicroSmart V 2.xx
Page 26
Servicing Instructions 227 470 35 B - 97.12
Motor control
The stepping motor is controlled in three stages. A TPU channel is used in the controller 68332
which generates the frequency of the stepping sequence. Using this frequency, the "state machine"
FSM_STEPPER generates the sequence for the quater step operation of the stepping motor in the
complex PLD. From the control sequence the motor driver module generates the signals for both
motor windings in two full bridges. To reduce power loss, the windings are controlled with constant
current.
The motor speed is set via the frequency of the stepping sequence. To avoid stepping loss, the
software changes the frequency of the stepping sequence when the motor is started.
The "state machine" has one input allowing the direction of rotation to be changed.
Once the motor is started, the processor does not require any more processing power for the motor.
No compensation is required for the motor. The internal TPU stepping motor control is not used
because it is designed for a positioning system and would constantly require CPU power for
continuous operation. To save energy during printing breaks, the motor driver is released or locked
via the lead MOTOR_INH_.
Photoelectric barrier analysis
The reflective light barrier has several functions:
-
checks if paper is available
-
mark reader in case of Z-fold paper
-
identifying an open paper
-
monitors if motor runs when using Z-fold paper
The paper signal PAPER_ERR_ reaches the CPLD via a comparator. The error state is stored in the
CPLD (signal PAPER_).
PAPER_ERR_ = PAPER_ = low
no paper, flap open, or mark below sensor
The processor polls the lead PAPER_ and resets the signal PAPER_ back to high via the lead
PAPER_RES.
