Week 7 · Displays & Signals

Session 33: IR remote control

Teach & buildFlex120 minLesson 22: Infrared Remote Control

Learning outcomes

Explain how a 38 kHz receiver demodulates a remote's signal
Wire the IR receiver after checking its pinout
Capture your remote's codes with IRremote 4.x
Map remote buttons to actions with a switch

Kit and components

Uno, IR receiver module, kit remote, servo or RGB LED circuit
Oscilloscope

Pre-reading about 20 min

Students read these on their phones before class. They are listed on the student Before class page.

Session plan

0:0010 min
Recap
Quiz: buses
0:1015 min
Demo
Light you cannot see
Point a phone camera at the remote to see its LED flash, then show the demodulated receiver output on the scope.
0:2530 min
Build
Capture the codes
Students run the worked sketch and record the protocol and command for at least six buttons.
0:5525 min
Measure
Scope the receiver output
Students capture one button press at 10 ms/div and identify the leader pulse and the data bits.
1:2030 min
Build
Remote-controlled outputs
Students use a switch on the command to set the servo angle or LED colour from their code table.
1:5010 min
Wrap-up
Remote or button?

Checkpoint: ready to move on?

Students have a table of their own remote's codes, and the remote controls an output through a switch.

Extension for fast finishers

Hold-to-repeat: make two buttons step the servo while they are held.

Catch-up path

Capture the codes and map two buttons only.

Homework and practice

Pre-reading for S34.

Facilitator notes

Receiver modules differ in pin order. Check the silkscreen before power - a reversed receiver gets hot.
Flex session: in a shorter course keep this lesson as final project material.