Introduction
Service Manual for the Accutherm Ultra Printer 1-9
Control Electronics
Overview
The printer has a main controller board containing microprocessor, FPGA,
memory, motor drivers, and sensor conditioning circuits used to control the
mechanism. The basic system clock was chosen to be 19.6608 Mhz. This clock is
multiplied in the main processor with a PLL to maximize execution speed and
used by the FPGA for optimum thermal print head load speed. External
communications is USB only.
Processor and Memory
The processor used in the Accutherm Ultra is a Motorola ColdFire MCF5253
running at 140 Mhz. with integrated USB controller. The processor interfaces,
through a 16 bit external bus, to a 64Mb Synchronous Dynamic Ram (SDRAM),
32Mb of Flash Memory, 8Kb of EEPROM, and a 2,910 logic element Field
Programmable Logic Array (FPGA). The processor contains general purpose I/O
pins which are used to directly control many of the printer functions including:
• Status LEDs
• USB Communications
• Print Head Data and Timing
• Print Head Temperature and Voltage monitoring
• Programming the FPGA
The remaining printer functions are
controlled though the FPGA including:
• Stacker motor control
• Cutter motor control
• Paper feed motor control
• Thermal print head loading and protection
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