28139 Parallax Inc, 28139 Datasheet - Page 25

• 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

Measuring the Resting State between Messages
When you press and hold a given key on the remote, the remote sends the code for that
key, then waits a while and sends it again. CountStartPulses.bs2 also can be modified to
search for this resting time between messages. This resting time is shown in Figure 1-9,
and it turns out to be an important factor in Boe-Bot navigation.
To measure this resting state with the BASIC Stamp module, all you have to do is think
of the high time between messages as a positive pulse with a very long duration. The
PULSIN
argument from 0 to 1. The
action if the measured time is less than 1000 (2 ms). This ensures that the brief high
pulses between the start pulse and data bits won't be reported. Instead, only the longer
high time between messages will be reported.
Example Program: CountRestingStates.bs2
√
√
√
√
Enter and run CountRestingStates.bs2.
Point the remote at the IR detector, and press and hold the 5 key.
Make sure high pulses in the 20 to 35 ms range (20,000 to 35,000 µs) are
detected.
Make a note of the actual duration of the resting state between messages here:
_____________.
command must be modified to search for a positive pulse by changing the
IR message
Resting time between messages
IF…THEN
statement also has to be modified so that it takes no
Chapter 1: Infrared Remote Communication · Page 15
IR message
Figure 1-9
Two IR
Messages
This screen
capture from
the Parallax
USB
Oscilloscope
shows two IR
messages and
the resting
state between
them.
State