Printronix P7000 Series Maintenance Manual page 389

Engine Controller
80C167 Microcontroller
The Siemens SAB 80C167 is a high-integration microcontroller with many
features that suit it extremely well to real-time control applications. This
controller and the MECA ASIC provide the functionality of three separate
processors used in earlier controller board architectures. In this manual, the
80C167 is referred to as the EC.
Bus Configuration
The 80C167 bus is configured for 18-bit address, 16-bit data, non-multiplexed
and segmented operation. The flash memory runs with zero wait states. An
external PAL is used for address decoding.
Power Reduction
The 80C167 chip has two power reduction modes: idle and Energy Star. Idle
mode is not used. In Energy Star mode, the +48V and all motors are
de-energized, but the EC operates as normal.
EC Flash Memory
The EC stores all boot code, program code, and tables in its own local flash
memory. This flash is organized as 64Kx16 bits and uses the same
technology as the DC flash: it is +5.0V-only and is rated for a minimum of
100,000 write/erase cycles. EC memory is fixed; it is soldered to the controller
board. Its contents can be updated through the DC. At run time, the EC also
stores tables in shared SDRAM, which is accessed through the Cajun bus.
MECA ASIC
The 80C167 uses many counters, PWM generators, and FIFOs in the MECA
to control printer motor functions. The MECA is a custom gate array,
specifically designed to drive this system.
Analog Drive Circuitry
The analog drive circuits convert +48 volts and +8.5 volts into the power used
to drive the motors and hammers in the printer. Sensors monitor the operation
and status of critical components within the printer.
The printer has five electric motors: two ribbon drive, one paper feed, one
platen open, and the shuttle motor. The shuttle motor is a brushless DC motor
driven by current control. The MPU encoder is used as feedback for motor
commutations, hammer fire timing, and motor stall detection. The paper feed
motor is a DC stepping motor driven by current control. The paper feed motor
may be driven in full, half, or 1/72 inch microsteps, depending on print
requirements. The ribbon drive system uses two DC stepping motors that
alternate drive and drag roles when the ribbon fabric reaches turnaround. The
drive ribbon motor is microstepped in voltage mode, while the drag motor is
loaded and monitored to maintain correct linear speed and tension. The
platen motor is driven in current mode and can be full or half stepped. The
overall current level may be reduced for standby modes.
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