SERIAL PORTS
SECTION 4
Page 4-4 RPC -320
You can access C OM0 and COM 1 buffers in three w ays:
1.
INP UT sta tement. This re moves a ll charac ters in
the buffer up to the term inator cha racter and puts
them into a variable.
When using the INPUT statement, program
execution is susp ended until a < cr> (Enter key) is
received. W hether this is a problem depends on
your particular application.
INPUT strips bit 7. This means ASCII characters
from 0 to 127 are rec eived.
2.
GET function. Char acters ar e rem oved one at a
time as an ASCII value. A 0 is returned when the
buffer is e mpty. Use the C OM function to
determine if the buffer is empty or if a 0 is an
A S C II v al ue . U s e U I
n
to select the serial port for
G E T.
If you don' t read the b uffer an d the buffer fills, all
subsequent characters are discarded.
3.
COM$(n) retrieves all characters in the buffer,
including other control codes (except CR).
ACCESSING COM0 AND COM1
INPU T and GET functions retrieve data using the UIn
comm and. UI0 r outes inputs to C OM 0 while U I1 inputs
from the CO M1 port. PRINT outputs are set by the
UOn command. UO0 prints out COM0 while UO1
outputs COM1 using the PRIN T comm and. PR INT #1,
is an alternative way to print to COM 1.
The following show how UIn and U On work.
100 UI0
Set to COM0
110 INPUT A
Get data from COM0 port
520 UI1
Switch to COM1 port
530 INPUT B
Get data from COM1 port
800 REM
P r in t t o C O M 0
810 P R I NT " T e m pe r at ur e : " , T
900 REM Print to COM 1
910 P R I N T #1 , " S e t p r e ss u re a t: " , C A
Power up default is set to COM 0.
DISABLING CONTROL-C
Program execution is terminated by entering a
< Cntl> < C> . To disable < Cntl> < C> so program
execution is not terminated, execute the following
statemen t:
DBY(38) = DBY(38) .OR. 1
COMMANDS
The following is a list of RPBASIC-52 commands used
for serial I/O. These commands and functions are
explained in the
BASIC-52 Programm ing Manual
and
RPBASIC-52 Software Supplement
in this manua l.
Comm and
Function
C L E AR C O M $
Clears serial input buffer
C O M $
Returns string from buffer
COM
Returns number of characters
in buffer
C O N F I G BA U D
Sets serial port parameters
GET
Returns a character fr om the
serial buffer
I N P U T
Receives string from port
LIST
Outputs program listing
P R I N T
Outputs data in various
form ats
PRINT #,
Prints to a specified port
SPC
Print out n number of spaces
STR
String handling commands
TAB
Tabs to predetermined
positions
UI0
Reroute inputs to COM0
UI1
Route inputs to COM1
UO0
Rerou te PRIN T statem ent to
C O M 0
UO1
Route P RINT statement to
C O M 1
U S I N G
PRINT formatting statement
SERIAL PORT PIN OUT
Pin outs for J1 and J2 are shown below. Unused pins
are open.
J1 &
N a m e
Direction
J2
from card
3
Tx
Out
4
RTS*
In