1. Interrupt

2. incoming Lab. Interrupt an asynchronous signal indicating the need for attention hardware interrupt/software interrupt call “interrupt service routine”(interrupt handler, interrupt routine) interrupt source/interrupt vector/interrupt priority

3. incoming Lab. 생활 속에 인터럽트 영화 감상 문자 영화 정지 답신 재생 중요 스팸 12341234 5678…5678… 1234512345 시간 Gom playercell phone interrupt

4. incoming Lab. program with or without interrupt b = *ADC0; c = *ADC1; a = b+c; i=0; while(i<10){ a += b; i++; } b = *ADC0; c = *ADC1; a = b+c; i=0; while(i<10){ a += b; i++; } without interrupt with interrupt if ( a>10 ) a = c; else a = b; interrupt service routine(ISR)

5. incoming Lab. interrupt is an asynchronous event b = *ADC0; c = *ADC1; a = b+c; i=0; while(i<10){ a += b; i++; } if ( a>10 ) a = c; else a = b; b = *ADC0; c = *ADC1; a = b+c; i=0; while(i<10){ a += b; i++; } if ( a>10 ) a = c; else a = b; ISR

6. incoming Lab. c.f.) function in program b = *ADC0; c = *ADC1; a = b+c; func(); i = 0; while(i<10){ a += b; i++; } b = *ADC0; c = *ADC1; a = b+c; i=0 while(i<10){ a += b; i++; } void func(){ if ( a>10 ) a = c; else a = b; }

7. incoming Lab. ATmega128 interrupt Source (I) 35 개

8. incoming Lab. ATmega128 interrupt Source (II)

9. incoming Lab. Interrupt 처리 과정 Interrupt request from an interrupt source 예 ) INT0 Signal If masked, ignore the interrupt. Program counter(PC) is saved. PC is changed to the program address according to the interrupt source 예 ) PC <= 0x0002 Jump to the Interrupt Service Routine (ISR) 예 ) jmp EXT_INT0 (PC <= EXT_INT0) After the end of ISR, PC is restored.

10. incoming Lab. Interrupt Vector Table memory address of an interrupt service routine

11. incoming Lab. External Interrupt : INT0~INT7 INT0~INT3 : PD0~PD3 (Port D) INT4~INT7 : PE4~PE7 (Port E)

12. incoming Lab. Global Interrupt Enable SREG(Status Register) I (7 bit) : Global Interrupt Enable 전체 인터럽트를 허용하도록 설정하는 비트 ‘1’ : interrupt enable ‘0’ : interrupt disable SEI : ‘1’ 로 변경 (interrupt enable) CLI : ‘0’ 으로 변경 (interrupt disable)

13. incoming Lab. EIMSK register External Interrupt MaSK register External Interrupt (INT0~INT7) 의 허용 여부를 제어 ‘1’ : enable ‘0’: disable 예 ) EIMSK = 0xA4; address : 0x59

14. incoming Lab. External Interrupt Control Register (EICRA, EICRB) Interrupt Trigger Level trigger  low level : ‘0’ 상태이면 interrupt trigger  high level : ‘1’ 상태이면 interrupt trigger Edge trigger  rising edge : ‘0’ -> ‘1’ 이면 interrupt trigger  falling edge : ‘1’ -> ‘0’ 이면 interrupt trigger EICRA, EIRCB 0x5A 0x6A

15. incoming Lab. EICRA, EICRB

16. incoming Lab. 예 ) Enable Interrupt INT0, rising edge DDRD &= 0xFE; /* PD0 : interrupt source, input */ EICRA = 0x03; EIMSK = 0x01; sei(); /* global interrupt enable */  SEI instruction 의 C code, mnemonic code  cli(); /* global interrupt disable */ INT7, falling edge; DDRE &= 0xEF; /* PE7 : interrupt source, input */ EICRB = 0x80; EIMSK = 0x80; sei(); /* global interrupt enable */

17. incoming Lab. Interrupt Service Routine ISR(vector, attributes) Format of WinAVR  C:\WinAVR-20100110\doc\avr-libc\avr-libc-user- manual.pdf 의 p.233 ~ vector : interrupt source  p.237 의 표 참조  예 ) INT0_vect : external interrupt 0 (PD0) attributes : interrupt 속성, 생략 가능 예 ) ISR(INT0_vect) { … } /* external interrupt 0 (PD0) 가 발생할 때 ISR */

18. incoming Lab. Interrupt Vector Table Initialize WinAVR : ISR(vector, attributes) ISR 의 시작 번지가 자동으로 해당 vector table 에 저장 in general ( 예 ) unsigned int *ivt; ivt = (unsigned int *)0x0002; *ivt = int_service_routine;  /* C program 에서는 함수의 이름이 주소를 나타냄 */ … void int_service_routine(){ /* interrupt service routine */ … }

19. incoming Lab. Interrupt Priority & EIFR 인터럽트의 우선 순위 두 개 이상의 인터럽트가 동시에 발생될 경우 하위 주소의 인터럽트가 상위 주소의 인터럽트 보다 우선 순위가 높다 예 ) INT0 > INT1 > … > USART0 > … interrupt flag register (EIFR) External Interrupt (INT0~INT7) 의 발생 여부를 나타냄

20. incoming Lab. Interrupt 실습 #include int main(){ DDRD = 0x18; EICRA = 0x02; /* falling edge */ EIMSK = 0x01; /* left S/W interrupt enable */ sei(); /* SEI instruction 의 C code, mnemonic code */ while(1); return 0; }

21. incoming Lab. falling edge or rising edge

22. incoming Lab. Interrupt Service Routine ISP(INT0_vect) { PORTD |= 0x10; }

23. incoming Lab. In flash program memory 0x0000 : jmp 0x0054 0x0002 : jmp 0x00a0 … 0x0054 : …. … 0x00a0 : …. …. …. : reti Reset or Restart INT0 (left S/W) main program interrupt service routine

24. incoming Lab. Interrupt 실습 : LED 다시 켜기, while 문만 변경 #include int main(){ … sei(); while(1) { if( (PIND & 0x01) == 1 ) PORTD &= 0xEF; } return 0; }

25. incoming Lab. Interrupt 실습 : INT1 (RIGHT) #include int main(){ DDRD = ________; EICRA = ________; EIMSK =________; sei(); while(1); return 0; }

26. incoming Lab. Interrupt Service Routine ISR(INT1_vect) { PORTD |= 0x10; }

27. incoming Lab. 실습 : INT0, INT1 모두 사용 #include int main(){ DDRD = ________; EICRA = ________; EIMSK =________; sei(); while(1); return 0; }

28. incoming Lab. 실습 : INT0, INT1 모두 사용 ISP(INT0_vect) /* Left S/W => LED Off */ { PORTD |= 0x10; } ISR(INT1_vect) /* Right S/W => LED On */ { PORTD &= 0xEF; }

29. incoming Lab. main switch problem : wait-polling int main() { … while (1) { cmd = rxd_char(); if( main S/W is left) { Motor Off; } else { switch(cmd){ case … unsigned char rxd_char() { unsigned char data; while( (UCSR0A & 0x80) == 0) ; data = UDR0 ; return data ; }

30. incoming Lab. one possible solution : still polling int main() { … while (1) { if( (UCSR0A & 0x80) != 0 ) cmd = UDR0 ; if( main S/W is left) { Motor Off; } else { switch(cmd){ case …

31. incoming Lab. solution with interrupt (I) int main() { … while (1) { cmd = rxd_char(); if( main S/W is left) { Motor Disable; } else { switch(cmd){ case … ISR(INT0_vect) { Motor Disable; } main S/W interrupt

32. incoming Lab. solution with interrupt (II) int main() { … while (1) { cmd = rxd_char(); if( … ) { Left Motor Disable; } else if (… ) { RightMotor Disable; } else { switch(cmd){ case … ISR(INT0_vect) { Left Motor Disable; } left S/W interrupt ISR(INT1_vect) { Right Motor Disable; } right S/W interrupt

33. incoming Lab. USART Interrupt USART0 사용 USCR0B Register RXCIE0 (7 bit) = ‘1’; USCR0B : ’18’ -> ’98’

34. incoming Lab. USART0 Interrupt Service Routine ISR(USART0_RX_vect) { Cmd_U0 = UDR0; /* Cmd_U0 : global 변수 */ } … unsigned char Cmd_U0; /* global 변수 선언 위치 */ int main() { …

35. incoming Lab. 변수의 허용 범위 block : {} 내의 선언문 및 실행문 block 내에서 선언된 변수는 block 내에서 만 유효 Example) int a = 2; printf(“%d\n”,a); { int a = 3; printf(“%d\n”,a); } printf(“%d\n”,a);

36. incoming Lab. USART0 interrupt program #include unsigned char Cmd_U0; int main(){ /* 초기화 code, Port I/O, USART0, Interrupt Enable */ while(1){ switch(Cmd_U0) { case : … } return 0; }

37. incoming Lab. USART0 interrupt 실습 ‘n’ : LED on, ‘f’ : LED off switch(Cmd_U0){ case ‘n’ : PORTD &= 0xEF; break; case ‘f’ : PORTD |= 0x10; break; default : }

38. incoming Lab. 실습 과제 모든 input 은 interrupt 로 처리 Left S/W 를 이용하여 left motor enable/disable ‘0’ : Disable ‘1’ : Enable Right S/W 를 이용하여 right motor enable/disable ‘0’ : Disable ‘1’ : Enable UART 통신을 이용하여 Motor 제어 Key map 정의  예 ) R : right forward, r : right backward