Engine Controller - IBM 6400 series Maintenance Manual

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.
The 166 used on the CMX board runs at 20MHz and is housed in a 100-pin
metric rectangular flat pack.
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 64K x16 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 functions convert 48 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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Principles of Operation