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Chapter 1. Overview Chapter 2. Emulation Guide Chapter 3. Build Your First Project Chapter 4. In System Programming
Chapter 5. USB Interface Installation Chapter 6. LED Display Application Chapter 9. FAQ Chapter 10. System Configuration and Service
Chapter 7. Basic Experiments
7.1. Experiment with LED 7.2. Experiment with Flowing LEDs 7.3. Experiment with Keys 7.4. Experiment with Beeper
7.5. Experiment with Relay 7.6. Experiment with LED Display 7.7. Experiment with Serial Port  
8.1. Experiment with Matrix Key 8.2. Experiment with Stepping Motor 8.3. Experiment with 1-Wire Digital Thermometer DS18B20
8.4. Experiment with 24C01 EEPROM 8.5. Experiment with 93C46 Serial EEPROM 8.6. Experiment with DS1302 Real-time Clock
8.7. Experiment with 8-bit Serial AD Converter ADC0832 8.8. Experiment with 1602 Character LCD Module 8.9. Experiment with 12864 Graphic LCD
8.10. Experiment with Infra-red Remote Controller 8.11. Experiment with Wireless Encoding Module Chapter 11. User Feedback

Chapter 8. Advanced Experiments

8.10. Experiment with Infra-red Remote Controller

Remote controller is widely used in daily life. Most of the consumer electronic product equipped with infra-red remote controlling facility. The remote controller basically is a simple transmitter of coded key signal, inside which transmitter IC is generally used for encoding. In this experiment, transmitter IC µPD6121 is used.

The µPD6121 is infrared remote control transmission ICs using the NEC transmission format that are ideally suited for TVs, VCRs, audio equipment, air conditioners, etc. By combining external diodes and resistors, a maximum of 65,536 custom codes can be specified. The IC comes in small packages, thus facilitating the design of light and compact remote control transmitters.

Transmission Format

The NEC transmission format consists of the transmission of a leader code, 16-bit custom codes (Custom Code, Custom Code’), and 16-bit data codes (Data Code, Data Code) at one time, as shown below.

Data Code is the inverted code of Data Code.

The leader code consists of a 9-ms carrier waveform and a 4.5-ms OFF waveform and is used as leader for the ensuing code to facilitate reception detection.

Codes use the PPM (Pulse Position Modulation) method, and the signals “1” and “0” are fixed by the interval between pulses.

Output Waveform

Remote (REM) output (from stage 2 , transmission occurs only when key is kept depressed)

Magnification of stage 1

Magnification of waveform 3

Magnification of waveform 2

Carrier waveform (Magnification of HIGH period of codes)

Schematic Diagram

Program Flow Chart

Step 1, read and check if the leader code is correct, otherwise initialize check condition and return.

Step 2, read custom and data code, then display.

Timer must be started before checking 0 and 1 code, otherwise, error will be caused.

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