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Infrared remote control experiment
Experiment component
1. IR remote control x1
2. Infrared receiving head x1
3. Buzzer x1
4. 220 Ω resistance x1
5. Breadboard & jumper wires
Experiment principle
If you want to decode remote control, you must understand the coding system of the remote
controller first. The coding system of the remote control we used is NEC protocol. Now let’s learn
about NEC protocol:
 NEC protocol introduction：
Feature：
（1）8-bit address spaces, 8-bit command spaces.
（2）address bits and command bits are transmitted twice for reliability.
（3）Pulse position modulation.
（4）Carrier frequency 38khz.
（5）Every bit’s time is 1.125ms or 2.25ms.
Protocol：
The above picture shows the typical NEC protocol pulse sequence. Note: This is the prior sending
the LSB (least significant bit) agreement.
Pulse propagation’s address is the 0x59 command 0x16 at the above. A message is start from a
9ms high level, followed by a 4.5ms low level (these two level made boot code) and then by the
address code and command code.
Address and command transfer twice. The second time all bits are inverted, can be used for use