Engine Controller - Printronix P5000 Maintenance Manual

Chapter 6
Controller Board

Engine Controller

The engine controller (EC) consists of four main elements:
•
80C166 Microcontroller
•
128KB 5.0V-only FLASH program memory, organized as 64K x 16 bits.
This memory is not expandable.
•
MECA (Mechanism Engine Control ASIC)
•
Analog drive circuitry
80C166 Microprocessor
The Siemens SAB 80C166 is a high-integration microcontroller. It has 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
80C166 is referred to as either the EC or the 166.
Bus Configuration
The 166 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 166 chip has two power reduction modes: idle and Energy Star. Idle
mode is not used. In Energy Star mode, +48V and all motors are de-
energized, but the 166 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 (through the serial or
parallel ports). At run time, the EC also stores tables in shared DRAM, which
is accessed through the Cajun bus.
MECA ASIC
The 166 uses numerous counters, PWM generators, and FIFOs in the MECA
to control many 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 are used to monitor
the operation and status of critical components within the printer.
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