Parallax BASIC Stamp 2e Programming Manual page 308

SEROUT - BASIC Stamp Command Reference
2. Pay attention to timing.
a. Be very careful to calculate and overestimate the amount of
time operations should take within the BASIC Stamp.
Misunderstanding the timing constraints is the source of most
problems with code that communicate serially.
b. If the serial communication in your project is bi-directional,
the above statement is even more critical.
3. Pay attention to wiring.
a. Take extra time to study and verify serial communication
wiring diagrams.
problems in communication, or no communication at all.
Make sure to connect the ground pins (Vss) between the
devices that are communicating serially.
4. Verify port setting on the PC and in the SERIN/SEROUT
commands.
a. Unmatched settings on the sender and receiver side will cause
garbled data transfers or no data transfers. If the data you
receive is unreadable, it is most likely a baud rate setting
error.
5. If data transmitted to the Stamp Editor's Debug Terminal is
garbled, verify the output format.
a. A common mistake is to send data with SEROUT in ASCII
format.
SEROUT 16, 84, [ DEC 0 ]. The first example will send a byte
equal to 0 to the PC, resulting in the Debug Terminal clearing
the screen (since 0 is the control character for a clear-screen
action).
Demo Program (SEROUT.bas)
' This program transmits the characters "A", "B", "C" and "D" (Inverted 2400 baud, N81) on
' I/O pin 0, followed by a number and a carriage return.
'{$STAMP BS1}
SYMBOL Result = W0
Result = 1500
Loop:
SERIN 0, N2400, ("ABCD"), #Result
PAUSE 1000
GOTO Loop
Page 306 • BASIC Stamp Programming Manual 2.0b • www.parallaxinc.com
A mistake in wiring can cause strange
For example, SEROUT 16, 84, [ 0 ]
'STAMP directive (specifies a BS1)
instead of
1