28139 Parallax Inc, 28139 Datasheet - Page 14

• 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

Page 4 · IR Remote for the Boe-Bot
HOW THE REMOTE SENDS MESSAGES
Figure 1-3 shows how the handheld remote can be used to send messages to a Boe-Bot.
When a button on the remote is pressed, it flashes its IR LED on/off at 38.5 kHz to
broadcast a code for that button. The code is produced by controlling the brief amounts
of time the IR LED flashes on and off. The sequence of IR broadcast times shown in the
figure corresponds to the beginning of the code that tells a SONY TV the 3 button has
been pressed. To send messages to a SONY TV, the remote has to broadcast IR for 2.4
ms signaling that a message is about to start. The message that follows consists of a
combination of 1.2 ms (binary-1) and 0.6 ms (binary-0) broadcasts. Notice how the IR
detector on the Boe-Bot sends low signals that match the time pattern broadcast by the
remote. The BASIC Stamp can then be programmed to detect, measure, record and
interpret the durations of low pulses in this pattern to figure out which key on the remote
was pressed.
Figure 1-3: Handheld Remote Infrared Messages