1. KyungHee Univ. 2-0 Parallel Port LED Interfaces

2. KyungHee Univ. 2-1 Output LEDs

3. KyungHee Univ. 2-2 Output LEDs  Direct Interface : 각 Output Pin 에 하나의 LED 을 접속 한다.  Scanned Interface : LED 는 Matrix 구조로 배치된다.  Multiplexed Interface : Multiplexing Hardware 사용 하여 Scanned Interface 보다 더 많은 LED 를 배치 할 수 있다.

4. KyungHee Univ. 2-3 Single LED Interface  Open Collector 를 이용한 LED 제어

5. KyungHee Univ. 2-4 8.2.1 Single LED Interface  LED 의 전류를 제어 하는 대표적인 방법

6. KyungHee Univ. 2-5 8.2.1 Single LED Interface

7. KyungHee Univ. 2-6 Single LED Interface Id = 10mA, Vd = 2V

8. KyungHee Univ. 2-7 Single LED Interface

9. KyungHee Univ. 2-8 8.2.1 Single LED Interface Id = (Vcc – Vd – Vce) / R R = (Vcc – Vd – Vce) / Id

10. KyungHee Univ. 2-9 Seven-Segment LED Interface

11. KyungHee Univ. 2-10 Seven-Segment LED Interface

12. KyungHee Univ. 2-11 Seven-Segment LED Interface

13. KyungHee Univ. 2-12 Seven-Segment LED Interface

14. KyungHee Univ. 2-13 8.2.3 Scanned Seven-Segment LED Interface  LED 의 동작 점이 10mA, 2V 이고,  3 개의 LED 를 스캔 하는 경우  각 LED 의 Duty 는 33% 가 된기 때문에  Active 되는 LED 의 동작 전류는 30mA 가 되어야 한다.

15. KyungHee Univ. 2-14 8.2.3 Scanned Seven-Segment LED Interface

16. KyungHee Univ. 2-15 C software interface of a scanned LED display. // MC68HC812A4 // PB7-PB0 output, 7 bit pattern // PC2-PC0 output, selects LED digit unsigned char code[3]; // binary codes static unsigned char select[3]={4,2,1}; unsigned int index; // 0,1,2 #define C5F 0x20 #pragma interrupt_handler TOC5handler() void TOC5handler(void){ TFLG1=C5F; // Acknowledge TC5=TOC5+10000; // every 5 ms PORTC=select[index]; // which LED? PORTB=code[index]; // enable if(++index==3) index=0;} void ritual(void) { asm(" sei"); // make atomic index=0; DDRC=0xFF; // outputs 7 segment code DDRB=0xFF; // outputs select LED TMSK1|=C5F; // Arm OC5 TIOS|=C5F; // enable OC5 TSCR|=0x80; // enable TMSK2=0x32; // 500 ns clock TC5=TCNT+10000; asm(" cli"); }

17. KyungHee Univ. 2-16 Scanned LED Interface Using the 7447 Seven- Segment Decoder Seven-Segment Decoder

18. KyungHee Univ. 2-17 C software interface of a multiplexed LED display. // MC9S12C32, CodeWarrior C unsigned short Global; // 12-bit packed BCD const struct LED { unsigned char enable; // select unsigned char shift; // bits to shift const struct LED *Next; }; // Link typedef const struct LED LEDType; typedef LEDType * LEDPtr; LEDType LEDTab[3]={ { 0x04, 8, &LEDTab[1] }, // Most sig { 0x02, 4, &LEDTab[2] }, { 0x01, 0, &LEDTab[0] }}; // least sig LEDPtr Pt; // Points to current digit void interrupt 13 TC5handler(void){ TFLG1 = 0x20; // Acknowledge TC5 = TC5+10000; // every 5 ms PTT = (Pt->enable) + (Global >> (pt->shift)) << 4); // BCD Unpacking and // BCD code -> PT4 -> PT7 Pt = Pt->Next; } void LED_Init(void) { asm sei // make atomic DDRT = 0xFF; // outputs to LED's Global = 0; Pt=&LEDTab[0]; TIE |= 0x20; // Arm OC5 TIOS |= 0x20; // enable OC5 TSCR1 = 0x80; // enable TSCR2 = 0x01; // 500 ns clock TC5 = TCNT+10000; asm cli }

19. KyungHee Univ. 2-18 Integrated LED Interface Using the MC14489 Display Driver  MC14489 Display Driver 를 이용할 경우의 장점  Chip Count 가 감소한다.  Scanning Function 이 hardware 적으로 수행된다.  MC14489 를 Cascade 하게 구성하여 큰 규모의 Display 장치를 용이 하게 구현 할 수 있다.

20. KyungHee Univ. 2-19 Integrated LED Interface Using the MC14489 Display Driver Packed BCD 를 이용한 24Bit Data 전송 예 Decimal Point Control 5 Digit Packed BCD

21. KyungHee Univ. 2-20 Integrated LED Interface Using the MC14489 Display Driver

22. KyungHee Univ. 2-21 C software interface of an integrated LED display. // MC68HC812A4 // PS5/MOSI = MC14489 DATA IN // PS6/SCLK = MC14489 CLOCK IN // PS7 (simple output) = MC14489 ENABLE void ritual(void) { DDRS |= 0xE0; // outputs to MC14489 SP0CR1=0x50; // bit meaning // 7 SPIE=0 no interrupts // 6 SPE=1 SPI enable // 5 SWOM=0 regular outputs // 4 MSTR=1 master // 3 CPOL=0 match timing with MC14489 // 2 CPHA=0 // 1 SSOE=0 PS7 is simple output // 0 LSBF=0 MSB first SP0CR2=0x00; // no pull-up, regular drive SP0BR=0x02; // 1Mhz SCLK PORTS|= 0x80; // ENABLE=1 PORTS&= 0x7F; // ENABLE=0 SP0DR= 0x01; // hex format while(SP0SR&0x80)==0){}; PORTS|=0x80;} // ENABLE=1 void LEDout(unsigned char data[3]){ //packed PORTS &= 0x7F; // ENABLE=0 SP0DR = data[2]; // send MSbyte while(SP0SR&0x80)==0){}; SP0DR = data[1]; // send middle byte while(SP0SR&0x80)==0){}; SP0DR = data[0]; // send LSbyte while(SP0SR&0x80)==0){}; PORTS |= 0x80;} // ENABLE=1