Parallax BASIC Stamp 2e, Programming Manual

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5: BASIC Stamp Command Reference – OUTPUT
BASIC Stamp Programming Manual 2.0c
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Page 195
OUTPUT
BS1 BS2 BS2e BS2sx BS2p
OUTPUT Pin
Function
Make the specified pin an output.
• Pin is a variable/constant/expression (0 – 15) that specifies which
I/O pin to set to output mode.
Explanation
There are several ways to make a pin an output. Commands that rely on
output pins, like PULSOUT and SEROUT, automatically change the
specified pin to output. Writing 1s to particular bits of the variable DIRS
makes the corresponding pins outputs. And then there’s the OUTPUT
command.
When a pin is an output, your program can change its state by writing to
the corresponding bit in the OUTS variable (PINS on the BS1). For
example:
OUTPUT 4
OUT4 = 1
When your program changes a pin from input to output, whatever state
happens to be in the corresponding bit of OUTS (PINS on the BS1) sets the
initial state of the pin. To simultaneously make a pin an output and set its
state use the HIGH and LOW commands.
Demo Program (INOUT.bas)
' This program demonstrates how the input/output direction of a pin is determined by
' the corresponding bit of DIRS. It also shows that the state of the pin itself (as
' reflected by the corresponding bit of PINS) is determined by the outside world when
' the pin is an input, and by the corresponding bit of PINS when it's an output. To
' set up the demo, connect a 10k resistor from +5V to P7 on the BASIC Stamp. The
' resistor to +5V puts a high (1) on the pin when it's an input. The BASIC Stamp can
' override this state by writing a low (0) to bit 7 of OUTS and changing the pin to output.
'{$STAMP BS1} 'STAMP directive (specifies a BS1)
INPUT 7 ' Make I/O pin 7 an input.
DEBUG "State of pin 7: ", #PIN7, CR
PIN7 = 0 ' Write 0 to output latch.
DEBUG "After 0 written to OUT7: ", #PIN7, CR
1 2
e
2
sx
2
p
2
1
1
NOTE: Expressions are not
allowed as arguments on the BS1.
The range of the Pin argument on
the BS1 is 0 – 7.
E
FFECTS OF SETTING AN INPUT PIN TO
AN OUTPUT
.