User`s manual

BL4S100 User’s Manual 43

4.2.2 Serial Communication

The following sample programs are found in the SAMPLES\BL4S1xx\RS232 subdirectory.

• PARITY.C—This sample program repeatedly sends byte values 0–127 from Serial Port D

to Serial Port F. The program will cycle through parity types on Serial Port D. Serial

Port F will always be checking parity, so parity errors should occur during most

sequences. The results are displayed in the Dynamic C STDIO window.

Connect Tx/1-W to CTS (RxF) on header J5 before compiling and

running this sample program. You may wish to do <Ctrl-Q> to stop

the program to see the data, which go by rather quickly.

NOTE: For the sequence that does yield parity errors, the errors won't

occur for each byte received. This is because certain byte patterns along with the stop bit will

appear to generate the correct parity for the UART.

• SIMPLE3WIRE.C—This program demonstrates basic RS-232

serial communication using the Dynamic C STDIO window. Fol-

low these instructions before running this sample program.

Connect Tx/1-W to CTS (RxF), then connect Rx to RTS (TxF)

before compiling and running this sample program.

• SIMPLE5WIRE.C—This program demonstrates 5-wire RS-232 serial communication

using the Dynamic C STDIO window. Follow these instructions before running this

sample program.

Before you compile and run this sample program, connect Tx/1-W

to Rx, then connect RTS to CTS.

To test flow control, disconnect RTS from CTS while running this

program. Characters should stop printing in the Dynamic C STDIO

window and should resume when RTS and CTS are connected again.

•

COMPUTER_PARITY.C—This sample program demonstrates using parity over a simple

three-wire RS-232 connection. Parity is selected for the BL4S100 and for the serial ter-

minal emulation program. Characters typed in either the Dynamic C STDIO window or

in the serial terminal emulation program are echoed in both displays. Parity errors are

counted and displayed by the Rabbit microprocessor on the BL4S100.

Before you compile and run this sample program, use the

long serial cable (Part No. 540-0094) to connect Tx (brown

wire), Rx (red wire) and GND (black wire) on header J5 to

a PC COM port.

Open a Hyperterminal session (

Start > Accessories >

Communications

). Select the PC COM port the cable is

connected to and set the default serial parameters:

Bits per second: 115200

Data bits: 8

Parity: None

RX TX/1W CTS RTS +5 V GND

GND