28139 Parallax Inc, 28139 Datasheet - Page 20

• Manufacturer Part Number: 28139
• Description: KIT REMOTE IR FOR BOE-BOT W/TEXT
• Manufacturer: Parallax Inc

Specifications of 28139

• Accessory Type: IR Remote
• Product: Microcontroller Accessories
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• For Use With/related Products: Boe-Bot®
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant, Contains lead / RoHS non-compliant

Let's say your program has a word variable named
duration. The 2.4 ms, 1.2 ms, and 0.6 ms pulses shown in Figure 1-7 are negative pulses.
To measure them with the IR detector circuit, you will have to use the command:
The high time between two low pulses can be measured as a positive pulse. True, it
doesn't contain any data, but it can be useful for figuring out how long an entire IR
message takes to transmit. By changing the
to 1, you can measure the duration of a positive pulse, like this:
Example Program: CountStartPulses.bs2
The first pulse that we will examine using the
This pulse won't be exactly 2.4 ms (2400 µs), but it should be fairly close, give or take
250 µs. This is the pulse that signifies that twelve more data pulses are about to be sent
by the remote.
PULSIN 9, 0, time
PULSIN 9, 1, time
High pulse vs. low pulse: If the voltage a BASIC Stamp I/O pin senses starts low, then
goes high for a while before returning to low, that's a high pulse. The term positive pulse
is also commonly used. The
high if the
A low pulse is the opposite: the signal will be high, then drop low for a while before
returning to the high state. It is also called a negative pulse. The
measures the amount of time the signal is low if the
State
argument is 1.
PULSIN
command measures the amount of time the signal is
PULSIN
PULSIN
time
command's
State
command is the 2.4 ms start pulse.
for storing the measured pulse
argument is 0.
State
PULSIN
argument from 0
Figure 1-7
A Closer Look at
the Pulses
command