Pulsout - Parallax BASIC Stamp 2e Programming Manual

2
1 2
e
1
NOTE: Expressions are not
allowed as arguments on the BS1.
The range of the Pin argument on
the BS1 is 0 – 7.
Table 5.63: PULSOUT Quick Facts.
C
ONTROLLING THE POLARITY OF THE
.
PULSE
W
ATCH OUT FOR UNDESIRABLE PULSE
.
GLITCHES
5: BASIC Stamp Command Reference – PULSOUT

PULSOUT

2 2 PULSOUT Pin, Period
sx p
Function
Generate a pulse on Pin with a width of Period.
• Pin is a variable/constant/expression (0 – 15) that specifies the I/O
pin to use. This pin will be set to output mode.
• Period is a variable/constant/expression (0 – 65535) that specifies
the duration of the pulse. The unit of time for Period is described in
Table 5.63.
Quick Facts
Units in Period
Maximum pulse
width
Explanation
PULSOUT sets Pin to output mode, inverts the state of that pin; waits for
the specified Period; then inverts the state of the pin again; returning the bit
to its original state. The unit of Period is described in Table 5.63. The
following example will generate a 100 us pulse on I/O pin 5 (of the BS2):
PULSOUT 5, 50
The polarity of the pulse depends on the state of the pin before the
command executes. In the example above, if pin 5 was low, PULSOUT
would produce a positive pulse. If the pin was high, PULSOUT would
produce a negative pulse.
If the pin is an input, the output state bit, OUT5 (PIN5 on the BS1) won't
necessarily match the state of the pin. What happens then? For example:
pin 7 is an input (DIR7 = 0) and pulled high by a resistor as shown in
Figure 5.26a. Suppose that pin 7 is low when we execute the instruction:
PULSOUT 7, 5
Figure 5.26b shows the sequence of events on that pin. Initially, pin 7 is
high. Its output driver is turned off (because it is in input mode), so the
BS1 BS2 BS2e BS2sx BS2p
BS1 BS2
10 µs 2 µs
655.35 ms 131.07 ms
' Generate a pulse on pin 5.
' Generate a pulse on pin 7.
BASIC Stamp Programming Manual 2.0c • www.parallaxinc.com • Page 243
BS2e BS2sx
2 µs 0.8 µs
131.07 ms 52.428 ms
BS2p
1.18 µs
55.479 ms