Basic interfacing of LEDs
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The document discusses interfacing LEDs with microcontrollers. It explains that LEDs are PN junction semiconductors that emit monochromatic light when forward-biased. It describes the data direction register (DDR) which determines whether pins on a given port are inputs or outputs. It also discusses the PORT register which sets the data values on pins. Finally, it provides a code example that blinks LEDs connected to port C using these registers and a delay function.
Basic interfacing of LEDs
- 2. A light-emitting diode (LED) is a PN junction semiconductor which emits monochromatic(single) light. When forward-biased (switched on), electron hole recombination releases energy in the form of photons. LIGHT EMITTING DIODES
- 3. Two configurations of LEDs…….. COMMON CATHODE COMMON ANODE
- 4. INTERFACING
- 5. DDR X Data Direction Register DDR X is used to determine the direction of data on each pin of a given port X Logic 1 -> specify pin as output port Logic 0 -> specify pin as input port Ex- DDRC=0 b 1 1 1 1 1 0 0 0 ; DDRC=0XF8; PC0 , PC1 , PC2 -> INPUT PINS PC3 , PC4 , PC5, PC6 , PC7 -> OUTPUT PINS
- 6. DDRB instruction gives the direction of data transfer as each port of atmega 16 is birectional..…… eg:DDRC=0b11110011; 0-- input 1-- output
- 7. INSTRUCTIONS USED PORT X PORT X is used to determine the data on each pin of a given port. Ex- PORTC=0 b 1 1 1 1 1 0 0 0 ;
- 8. PORT instruction gives data to be sent on the port eg- PORTC=0b01011011; 1 1 1 1 1
- 9. PORT instruction gives data to be sent on the port eg- PORTC=0b01011011;
- 10. INSTRUCTIONS USED _delay_ms(); It is used to provide a delay of specific time in milliseconds in the program. Ex- _delay_ms(1000); ->provides delay of 1 second
- 11. PROGRAM- #define F_CPU 16000000 #include <avr/io.h> #include <util/delay.h> int main(void) { DDRC=0 b 0 0 0 0 1 1 1 1; //data direction register for port C// while( 1 ) { //infinite loop// PORTC=0 b 0 0 0 0 1 1 1 1 ; //Data on port C// _delay_ms(1 0 0 0) ; //Delay of 1 sec// PORTC=0 b 0 0 0 0 0 0 0 0 ; _delay_ms(1 0 0 0) ; } }
- 12. OUTPUT 00:00 sec
- 13. OUTPUT 00:01 sec
- 14. OUTPUT 00:02 sec
- 15. OUTPUT 00:03 sec
- 16. Now try and generate the next pattern on your own……………………………………….
- 17. OUTPUT 00:01 sec
- 18. OUTPUT 00:02 sec
- 19. OUTPUT 00:03 sec
- 20. OUTPUT 00:04 sec