20-101-1051 Datasheet, PDF (99/165 Pages) List of Unclassifed Manufacturers – C-Programmable Core Module with NAND Flash Mass Storage and Ethernet

B.4.6.1 RS-232
RS-232 serial communication on the Prototyping Board is supported by an RS-232 trans-
ceiver installed at U9. This transceiver provides the voltage output, slew rate, and input
voltage immunity required to meet the RS-232 serial communication protocol. Basically,
the chip translates the Rabbit 3000’s signals to RS-232 signal levels. Note that the polarity
is reversed in an RS-232 circuit so that a +5 V output becomes approximately -10 V and 0
V is output as +10 V. The RS-232 transceiver also provides the proper line loading for
reliable communication.
RS-232 can be used effectively at the RCM3365/RCM3375 module’s maximum baud rate
for distances of up to 15 m.
RS-232 flow control on an RS-232 port is initiated in software using the
serXflowcontrolOn function call from RS232.LIB, where X is the serial port (E or F).
The locations of the flow control lines are specified using a set of five macros.
SERX_RTS_PORT—Data register for the parallel port that the RTS line is on (e.g., PGDR).
SERX_RTS_SHADOW—Shadow register for the RTS line's parallel port (e.g., PGDRShadow).
SERX_RTS_BIT—The bit number for the RTS line.
SERX_CTS_PORT—Data register for the parallel port that the CTS line is on (e.g., PCDRShadow).
SERX_CTS_BIT—The bit number for the CTS line.
Standard 3-wire RS-232 communication using Serial Ports E and F is illustrated in the fol-
lowing sample code.
#define EINBUFSIZE 15 // set size of circular buffers in bytes
#define EOUTBUFSIZE 15
#define FINBUFSIZE 15
#define FOUTBUFSIZE 15
#define MYBAUD 115200 // set baud rate
#endif
main(){
serEopen(_MYBAUD);
serFopen(_MYBAUD);
serEwrFlush();
serErdFlush();
serFwrFlush();
serFrdFlush();
serEclose(_MYBAUD);
serFclose(_MYBAUD);
}
// open Serial Ports E and F
// flush their input and transmit buffers
// close Serial Ports C and D
User’s Manual
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