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The Casio FP-12 Thermal Printer

• User's Manual (415kB)
• Circuit diagram
• Sanyo LB1256 driver IC data sheet
• Photograph of the PCB (component side)
• Photograph of the PCB (foil side)
• Photograph of the printing mechanism (bottom view)
• Photograph of the printing mechanism (top view)
• Sample printout - character codes $00 to $7F

Some notes to the circuit diagram

The microprocessor gets its power from the calculator (the internal rechargeable battery powers only the printing mechanism and the LB1256 driver).
The thermal head pulse width is ca. 1.5 ms.
The tacho magnet is attached to the motor's shaft. It allows (along with the switch) to determine the head position.

Construction project - parallel to FP-12 interface

This interface allows to drive the Casio FP-12 printer from the PC parallel port. It emulates a standard ASCII text printer, and should work with any operating system. The required +5V supply can be drawn from the keyboard, PS2 mouse, or USB port.

Only a minimal subset of Centronics control signals has been implemented. Particularly the Ack signal is omitted. However, this signal was designed to be used for an interrupt driven data transfer, and is usually ignored. When necessary it could be generated from the falling edge of the Busy signal with a monostable.

The project was meant to be an exercise to verify the reverse-engineered communication protocol.

par2fp12.zip - AVR source code