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** Notes for the CASIO Interface Schematic (schematic.gif) **
The circuit is essentially straight out of the Maxim data sheet as it's just a
straight TTL - RS-232 conversion. The power supply comes from the DTR and RTS
which must both be asserted (brought positive) by the software if the interface
is to work. The parts are relatively inexpensive and readily available.
It's a good idea to socket the MAX232 just in case you want to recycle it in future.
The RX and TX lines are at RS-232 levels while the Rx and Tx lines are at
logic levels. Remember that the CASIO must not experience voltages above
logic level so be very careful when wiring it up. All the GND lines should
be connected. The serial output is TX which is translated to casio-level Tx.
Likewise the casio level Rx is converted to RX at RS-232 levels.
The main idea behind this interface, unlike the others I have seen, is that
the cable to connect to the SF organizer is not an integral part of the interface.
Instead the interface has a 2.5mm socket just like an organizer and the cable that
connects the interface to the diary is the same as that for connecting two diaries
together, i.e. a (null modem) cable with two 2.5mm jacks at either end.
This gives you an SF interconnection cable for 'free'.
I built my interface in a small D25 box with a female D25 connector for
connection to old PC's and Amigas. More recent machines use a D-9 serial connector
so a simple D-25 to D-9 connector cable is needed (which comes in useful in any case).
NB - This may not work with some Digital Diaries - notably the SF-4300
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