BASIC stamp manual v2.2

5: BASIC Stamp Command Reference – INPUT
BASIC Stamp Syntax and Reference Manual 2.2 • www.parallax.com • Page 243
INPUT
BS1 BS2 BS2e BS2sx BS2p BS2pe BS2px
INPUT Pin
Function
Make the specified pin an input.
• Pin is a variable/constant/expression (0 – 15) that specifies which
I/O pin to set to input mode.
Quick Facts
Table 5.41: INPUT Quick Facts.
BS1 All BS2 Models
Input Pin
Variables
PINS; PIN0 through PIN7 INS; IN0 through IN15
Related
Commands
OUTPUT and REVERSE
Explanation
There are several ways to make a pin an input. When a program begins,
all of the BASIC Stamp's pins are inputs. Commands that rely on input
pins, like PULSIN and SERIN, automatically change the specified pin to
input. Writing 0s to particular bits of the variable DIRS makes the
corresponding pins inputs. And then there’s the INPUT command.
When a pin is an input, your program can check its state by reading the
corresponding INS variable (PINS on the BS1). For example:
INPUT 4
Hold:
IF IN4 = 0 THEN Hold ' stay here until P4 = 1
The code above will read the state of P4 as set by external circuitry. If
nothing is connected to P4, it will alternate between states (1 or 0)
apparently at random.
What happens if your program writes to the OUTS bit (PINS bit on the
BS1) of a pin that is set up as an input? The value is stored in OUTS (PINS
on the BS1), but has no effect on the outside world. If the pin is changed to
output, the last value written to the corresponding OUTS bit (or PINS bit
1
A
ll 2
NOTE: Expressions are not allowed as
arguments on the BS1. The range of
the PIN argument on the BS1 is 0 – 7.
1
All 2