Building the Serial Interface:
Discrete Version
Introduction:
There are many designs for serial interface circuits out there, most of them use IC's called transcievers.
The important thing to know about the Dreamcast serial port is that uses CMOS level transmission. Which
typically goes from 0 to 3V.
The PC's COM port on the other hand, uses the standard RS-232C voltage
levels, which are typically -12V to 12V, but are rated to go as high as -25 to +25V. The high voltage
the COM ports use is due to RS-232 technology's age, and its history with electromechanical devices.
Although nowadays RS-232 is being phased out, in 1999 it was still in frequent use and was viable
means of transmission for Dreamcast to Dreamcast communication. The nice thing about serial RS-232
transmission is that it is relatively simple in concept, compared to its successors like USB.
Discrete Component Design:
First I decided to test the simpliest design. It would be the quickest to build,
and would seemingly be the easiest to test and debug. Take a look at the schematic below:
The adapter shown in the schematic converts RS-232 levels to 0-5V TTL/CMOS signals.
This adapter does not support handshaking, that is CTS and RTS are not used. The circuit is a replica
of a serial interface to a PDA called the
"daVinci"
The circuit is said to be able to work at a 152000 baud rate
(thanks to Jesus Arias)
More Testing to be done soon, including PC Screenshots, better Circuit Picture, Voltage levels, Circuit Description, Etc.
For more information concerning Dreamcast serial transmission in the meantime refer to the
Transciever IC design.
Here is the breadboarded ready to use circuit I made:
Click here for the Serial Interface with Transciever Integrated Circuit
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