Saturday, July 30, 2011

TTL/RS-232 module

I developed this TTL/RS232 module using a typical MAX232 chip.  It is a RS-232 serial communiations transceiver with two transmit and two receive channels.  It converts from TTL logic (0V=low, 5V=high) to RS-232 signals (approximately -10V to +10V in this case); see the datasheet for more specifics.  The 6 pin header has 5V, GND, RX, TX, DTR, CTS.  The 10 pin header includes all the DB-9 pins, with the DB-9 female connector attached via ribbon cable and socket.  This model of the Maxim chip uses 0.1uF capacitors.  I could have used the MAX233 which has is an extra 2 pins wide but doesn't need any added capacitors so is easier to work with.  LEDs are included to show send/receive and cts/rts activity.  Two of the resistors for the LEDs ended up on the reverse side of the board.

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