Casio Serial Cable

This Casio serial cable circuit interfaces the Casio "fx" range of calculators to the serial port of a PC computer. It was first tested and used with the Casio fx-7700gb calculator, which has the necessary data communications port. If you have programmed your calculator with math functions and you need to backup this data, then a cable such as this is useful for transferring the programs to the PC hard disk. Transferring and sharing programs is also a useful facility to have within a school environment.

Serial Communications

This circuit uses a minimum number of components, and is built on a small piece of prototyping board. I kept the design and build simple so that a student may be able to build it as an electronics project for school.

A MAX232CPE, which is a commonly available integrated circuit (IC) is used for serial communications to convert the voltage levels between CMOS and TTL standards. This type of communication interface is very common with modern handheld gadgets and appears to work well for this application.

Serial Ports

There are a huge number of programmable calculators on the market today, mainly by Texas Instruments and Casio, with a wide and differing array of communications ports. This circuit is only for those calculators capable of communicating with the serial port of a PC.

This particular circuit is for a Casio calculator with a three contact 2.5 mm jack plug that uses serial communications at TTL / CMOS levels. I have not tested this with every calculator, so you build this at your own risk. Do not use this circuit if your calculator has a different port.

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