Arduino Infrared controller

Lala ·

更新时间:2024-09-21

· 839 次阅读

1. Hardwares parts Receiver

item	Quantity
SparkFun RedBoard	1
IR receiver	1
330 Ω\OmegaΩ resistor	1
Jumper	3
Cable	1

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Transmitter

item	Value
Arduino UNO Board	1
Infrared LED	1
330 Ω\OmegaΩ resistor	1
1 KΩ\OmegaΩ resistor	1
Bottom	1
Jumper	7
Cable	1

— Graphs are created by using Autodesk Tinkercad

Picture:
The red one is receiver. Blue one is transmitter. 在这里插入图片描述

2. Softwares Parts 1. Import library --IRremote 2. Receiver code

#include "IRremote.h"
int RECV_PIN = 12; //Define Receiver PinNumber 12
int a = 0;
IRrecv irrecv(RECV_PIN); //Create the receiver object
decode_results results; //Define results
void setup()
{
    Serial.begin(9600);
    irrecv.enableIRIn();     // Initializes the infrared receiver
}
void loop() {
    if (irrecv.decode(&results)) {// return true
        Serial.println(results.value, HEX); // HEX hexadecimal, or base 16
        irrecv.resume(); // After receiving, this must be called to reset the receiver
                         // and prepare it to receive another code.
    }
    delay(110);
}

3. Transmitter code

#include                   
const int buttonPin = 4; // Define Button PinNumber 4
int buttonState = 0; //Initial states =0                  
IRsend irsend; //Define infrared 
void setup()
{
pinMode(buttonPin, INPUT); // Setting Button Pin4 = Input
}
void loop()
{
buttonState = digitalRead(buttonPin);// Read 0 or 1
if (buttonState == HIGH) { //if 1 Sending messages
irsend.sendNEC(0x4CB3817E, 32);   // Sending NEC code
}

3. Build a TV controller Step 1

Upload code into board, open the Serial Monitor.
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Step 2

Recording signal from TV controller.
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We can see NEC code of the signal for turn on/ turn off is 4AB0F7B6.

Step 3

Open the transmitter code and update signal to 4AB0F7B6. Upload transmitter code to Arduino(transmitter)

Step 4

Testing!!! 在这里插入图片描述

4. Questions to Questions 1. What is NEC? How does it work?

The NEC Infrared Transmission Protocol uses pulse distance encoding of the message bits. Each pulse burst (mark – RC transmitter ON) is 562.5µs in length, at a carrier frequency of 38kHz (26.3µs).

Logical bits are transmitted as following:

Logical ‘0’ – a 562.5µs pulse burst followed by a 562.5µs space, with a total transmit time of 1.125ms
Logical ‘1’ – a 562.5µs pulse burst followed by a 1.6875ms space, with a total transmit time of 2.25ms

a 9ms leading pulse burst (16 times the pulse burst length used for a logical data bit) a 4.5ms space the 8-bit address for the receiving device the 8-bit logical inverse of the address the 8-bit command the 8-bit logical inverse of the command a final 562.5µs pulse burst to signify the end of message transmission.

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2. Why Hex number system in Arduino code?

The NEC system is 32 bits in Binary number systems which can be translated to 8 bits in Hex number system. It is more convenient to read for human.

In C/C++, Hex number must started with 0x

3. Why carrier frequency is 38Hz?

The range of carrier frequency always in 38Hz to 60Hz.
The range is decided by the crystal oscillator at topic. The frequency of crystal oscillator in IR LED is 455Hz. After a frequency divide processing, (455Hz /12 ≈\approx≈ 38Hz) We get a frequency which is 38Hz.

Frequency of Single-Chip Microcomputer . Crystal oscillator is 8
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