Specifications

2–21
Principles of Operation
Mechanism Driver Board
The mechanism driver board, acting on timing and control signals from the
CCB, controls real–time operation of the electromechanical printer systems.
Functionally, the board consists of the following subsystems:
• An 8032 microcontroller controls ribbon, shuttle, and platen drives,
and communication with the controller board. This 8032 is called
the RSP (Ribbon/Shuttle/Platen) controller.
• The interface to the power supply.
• Pulse–width modulator (PWM) current mode / voltage mode
full–bridge power amplifiers connected directly to the shuttle,
ribbon, paper feed, and platen open motors. Current mode is used
for the paper feed motor, voltage mode is used for the ribbon and
shuttle motors.
• The paper feed controller (PFC) accepts control codes from the
controller board for each motor phase to vector–control the paper
feed motor.
• The shuttle drive controller receives speed commands from the
controller board through the 8032 microcontroller and commands
the speed of the three–phase brushless DC shuttle motor.
• The ribbon drive controller, based around the 8032 microcontroller,
receives commands from the controller board and drives two DC
stepper motors, regulating the speed and tension of the ribbon and
monitoring the end of ribbon sensors.
• The platen drive controller for reverse paper feed receives
commands from the 8032 microcontroller (RSP).
• Fault detection circuitry samples and senses heat sink temperature,
ribbon speed, shuttle speed, hammer driver circuitry, hammer bank
coil temperatures, power supply voltages, and fault communication
with the controller board.
• Circuitry that registers magnetic pick–up unit (MPU) output,
processes it for the logic interface, and sends it to the controller
board for timing hammer fire.
Figure 2–14 summarizes mechanism driver board operation in block diagram
form.