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Lin Shaodun A0066078X Delay 1s by NOP ; clock frequency is 40MHz, delay 1s = 200x250x200x4x25nS delay1s movlw D'200' movwf delay_cnt1,A loop1 movlw D'250' movwf delay_cnt2,A loop2 movlw D'19 movwf delay_cnt3,A loop3 nop decfsz delay_cnt3,F, A goto loop3 decfsz delay_cnt2,F, A goto loop2 decfsz delay_cnt1,F,A goto loop1 return Use PWM mode, output to CCP1. The value to be written to PR2:16M/4/16/2K-1=124 The value to be written to CCPR1L (and CCPR1H) =125x60%=75 start movlw 0x7C ;set period value to 124 movwf PR2, A movlw 0x4B ; set duty cycle value to 75 movwf CCPR1L, A movwf CCPR1H, A bcf TRISC,2,A ; configure CCP1 pin for output movlw 0x81 ; enable Timer 3 in 16-bit mode and use movwf T3CON, A ; Timer 2 as time base for PWM1 thru PWM5 clrf TMR2, A ; force TMR2 to count from 0 movlw 0x07 ; enable Timer 2 and set its prescaler to 16 movwf T2CON, A movlw 0x0C ;enable CCP1 PWM mode movwf CCP1CON, A Counting with interrupt and output to PORTD #include <p18F8720.inc> count_1 set 0x10 ; counter outputs to lower 4 bit of PORTD count_2 set 0x11 ; counter outputs to higher 4 bit of PORTD output set 0x12 ; combined output to PORTD org 0x00 goto start org 0x08 goto int0; interrupt vector retfie org 0x18 retfie start clrf count_1, A ; initialize the counter 1 to 0 clrf count_2, A ; initialize the counter 2 to 0 movlw 0x00 ; config PORTD pins for output movwf TRISD ; call update ; call “update” subroutine bsf RCON, IPEN, A ; enable priority interrupt bsf INTCON, GIE ; enable global interrupt bsf INTCON, INT0IE ; enable INT0 interrupt bsf INTCON3, INT1IE ; enable INT1 interrupt bsf INTCON2, INTEDG0 ; set edge triggering for INT0 bcf INTCON2, INTEDG1 ; set edge triggering for INT1 bcf INTCON,INT0IF ; clear INT0 flag bcf INTCON,INT1IF ; clear INT1 flag forever goto forever ; INT0 interrupt service routine int0 btfsc INTCON3,INT1IF ; check if INT1 interrupt trigged goto int1 ; goto int1 routine if INT1 trigged bcf INTCON,INT0IF ; clear the INT0 interrupt flag bit movlw 0x0F cpfseq count_1, A ; was count_1 equal to 15 already? goto count_1_add_1 ; goto count_1_add_1 if count_1 < 15 clrf count_1, A ; reset count_1 to 0 after reaching 15 goto count_1_update count_1_add_1 incf count_1, F, A;[count_1]=[count_1]+1 count_1_update call update; call “update” subroutine retfie fast ;INT1 interrupt service routine int1 bcf INTCON3,INT1IF ; clear the INT1 interrupt flag bit movlw 0x0F cpfseq count_2, A ; was count_2 equal to 15 already? goto count_2_add_1 clrf count_2,A ; reset count_2 to 0 after reaching 15 goto count_2_update count_2_add_1 incf count_2, F, A ; [count_2]=[count_2]+1 count_2_update call update ; call “update” subroutine retfie fast update movff count_2,output ; [output]=[count_2] swapf output,F,A; swap nibbles of [output] register movf count_1, W, A ; WREG = [count_1] xorwf output, F, A ; [output]=[count_1]XOR[output] movff output, PORTD ; sent combined output to port D return end Interrupt frequency = = , Instruction frequency = =4, Frequency ratio = = = 32000 = (124 + 1) × 16 × 16 movlw D’124’ ; load 124 into PR2 so that TMR2 counts movwf PR2,A ; up to 124 and reset bsf RCON,IPEN,A ; enable priority interrupt bsf IPR1,TMR2IP,A ; place TMR2 interrupt at high priority bcf PIR1,TMR2IF,A ; clear TMR2 interrupt flag movlw 0xC0 movwf INTCON, ; enable global interrupt movlw 0x7E ; enable TMR2, set prescaler to 16, movwf T2CON,A ; set postscaler to 16 bsf PIE1,TMR2IE,A ; enable TMR2 overflow interrupt Add 32 8-bit numbers, squared and averaged no_of_loop set 0x30 ;loop index sum_temp1 set 0x31 ;temporary data register for sum calculation sum_temp2 set 0x32 ;temporary data register for sum calculation sum_temp3 se t0x33 ;temporary data register for sum calculation org 0x00 goto start org 0x08 retfie org 0x18 retfie start movlw D’32’ ; WREG = array size (32) movwf no_of_loop ;set number of loops equal to array size movlw upper array movwf TBLPTRU,A movlw high array movwf TBLPTRH,A movlw low array movwf TBLPTRL,A loop TBLRD*+ ; read an array element into TABLAT movf TABLAT,W,A ;WREG = array element mulwf TABLAT,A ;square the array element movf PRODL,W,A ;WREG = lower byte of squared number addwf sum_temp1,F,A ; sum_temp1 = sum_temp1 + lower byte movf PRODH,W,A; WREG = upper byte of squared number addwfc sum_temp2,F,A; sum_temp2 = sum_temp2 + upper byte BNC next ; branch if no carry incf sum_temp3,F,A ; sum_temp3 = sum_temp3 + 1 (from carry) next decfsz no_of_loop,F,A bra loop movlw 0x05 ; set loop count to 5 (2 5 =32) div bcf STATUS, C, A ; clear the C flag rrcf sum_temp3, F, A ; shift the bits to right 1 place rrcf sum_temp2, F, A rrcf sum_temp1, F, A decfsz WREG, W, A ; have we shifted right five places yet? bra div ; not yet, continue movff sum_temp2,0x22 movff sum_temp1,0x21 end Brake motor brake bsf PORTB,RB4,A ; reverse the applied voltage movlw 0x00 . movwf CCPRlL,A ; set PWMl duty cycle to 0 call brake-time ; wait for brake time bcf PORTB,RB4,A ; stop braking return Display in 7-segment LED with 1s delay In 100 ms, =1x10 6 instructions. Using prescaler 16, 1x10 6 =16x62500. 65535-62500=3035. org 0x00 goto start org 0x08 retfie org 0x18 retfie start clrf TRISD, A ; configure port D for output movlw 0x04 ; 4 digits to be displayed movwf loop_cnt movlw upper display_tab movwf TBLPTRU, A movlw high display_tab movwf TBLPTRH, A movlw low display_tab movwf TBLPTRL, A loop tblrd*+ movff TABLAT, PORTD call wait_1s ; wait for 1 second decfsz loop_cnt, F, A ; decrement the loop count goto loop forever goto forever wait_1s movlw 0x83 ;enable TMR0, select internal clock movwf T0CON, A ;set prescaler to 16 movlw 0x0A ;load 10 into PRODL movwf PRODL, A loopd movlw 0x0B ;load 3035 into TMR0, it will roll over in 62500 clock cycles movwf TMR0H, A movlw 0xDB movwf TMR0L, A bcf INTCON, TMR01F, A ;clear TMR0IF flag wait btfss INTCON, TMR01F, A ;wait until 100 ms is over bra wait decfsz PRODL, F, A bra loopd ;repeat 10 times to get 1s delay return display_tab db 0x79, 0x6D, 0x30, 0x7E end Scan Keypad , return value in WREG keypad_dir equ TRISB ; keypad direction control register keypad equ PORTB ; keypad port get_key movlw 0x0F ; configure the upper four pins of keypad movwf keypad_dir,A ; port for output, others for input movlw 0xF0 iorwf keypad, F ; set all keypad rows to high scan_r0 movlw 0xEF andwf keypad,F,A ; prepare to scan row 0 (driven by RB4) scan_k0 btfss keypad,0,A ; check key 0 goto db_key0 scan_k1 btfss keypad,1,A ; check key 1 goto db_key1 scan_k2 btfss keypad,2,A ; check key 2 goto db_key2 scan_k3 btfss keypad,3,A ; check key 3 goto db_key3 scan_r1 movlw 0xFF iolwf keypad,F,A bcf keypad,5 ; prep to scan row 1 (by RB5) scan_k4 btfss keypad,0,A ; check key 4 goto db_key4 scan_k5 btfss keypad,1,A ; check key 5 goto db_key5 scan_k6 btfss keypad,2,A ; check key 6 goto db_key6 scan_k7 btfss keypad,3,A ; check key 7 goto db_key7 … … db_key0 call wait10ms btfsc keypad,0,A ; is key 0 still closed? goto scan_k1; key 0 not pressed, check key 1 movlw 0x30 return db_key1 call wait10ms btfsc keypad, 1, A ; is key 1 still closed? goto scan_k2 movlw0x31 return db_key2 call wait10ms btfsc keypad,2,A ; is key 2 still closed? goto scan_k3 movlw0x32 return db_key3 call wait10ms btfsc keypad,3,A goto scan_r1 movlw0x33 db_key4 call wait10ms btfsc keypad,0,A goto scan_k1; movlw 0x34 return db_key5 call wait10ms btfsc keypad,1,A goto scan_k2 movlw0x35 return db_key6 call wait10ms btfsc keypad,2,A goto scan_k3 movlw0x36 return db_key7 call wait10ms btfsc keypad,3,A goto scan_r2 movlw0x37 return … … return Delay 10mS by interrupt ; Creates a 10 ms delay using timer 0 with f OSC= 32 MHz. wait10ms bcf INTCON,INT0IE,A ; disable TMR0 interrupt bcf INTCON,INT0IF,A ; clear TMR0IF flag movlw 0x03 ; configure TMR0 with 1:16 prescaler movwf T0CON,A ; configure TMR0 movlw 0xEC movwf TMR0H,A movlw 0x83 movwf TMR0L,A ; load 60547 into TMR0 ; TMR0 will overflow in (5000-12) counts bsf T0CON,TMR0ON,A ;enable TMR0 dlyloop btfss INTCON,INT0IF,A ;is 10 ms over yet? goto dlyloop return Use Timer0 as a timer to create a one-second delay and use Timer1 as a counter to count the rising (or falling) edges of an unknown signal (at the T1CKI pin) t1ov_cnt set 0x00 ; Timer1 rollover interrupt count freq set 0x01 ; to save the contents of Timer1 at the end org 0x00 goto start org0x08 btfss PIR1,TMR1IF,A ; skip if Timer1 roll-over interrupt retfie ; return if not Timer1 interrupt bcf PIR1, TMR1IF,A ; clear the interrupt flag incf t1ov_cnt,F,A ; increment Timer1 roll-over count retfie org0x18 retfie start clrf t1ov_cnt, A ; initialize Timer1 overflow cnt to 0 clrf freq,A clrf freq+1,A ; initialize frequency to 0 clrf TMR1H clrf TMR1L ; initialize Timer1 to 0 clrf PIR1 ; clear all interrupt flags bsf RCON,IPEN,A ; enable priority interrupt movlw 0x01 movwf IPR1,A ; set TMR1 interrupt to high priority movwf PIE1,A ; enable Timer1 roll-over interrupt movlw 0x87 ; enable Timer1, select external clock, set movwf T1CON,A ; prescaler to 1, disable crystal oscillator movlw 0xC0 movwf INTCON,A ; enable global and peripheral interrupt movlw 0x0A movwf PRODL,A ; prepare to call delay to wait for 1 second call delay ; Timer1 overflow interrupt occur in this second movff TMR1L,freq ; save frequency low byte movff TMR1H,freq+1 ; save frequency high byte bcfINTCON,GIE,A ; disable global interrupt forever nop bra forever end Enable A/D interrupt Bsf RCON,IPEN ; enable priority interrupt Bsf IPR1,ADIP ; enable A/D to high priority Bcf PIR1,ADIF ; clear ADIF flag Bsf PIE1,ADIE ; enable A/D interrupt movlw 0xC0 movwf INTCON ; enable global and peripheral interrupts Use the CCP channel 1 in capture mode to measure the period of an unknown signal org 0x00 goto start org 0x08 retfie org0x18 retfie start bsf TRISC,CCP1,A ; configure CCP1 pin for input movlw 0x81 movwf T3CON,A ; use TMR1 as the time base of CCP1 capture bcf PIE1,CCP1IE,A ; disable CCP1 capture interrupt movlw 0x81 ; enable Timer1, prescaler set to 1, movwf T1CON,A ; 16-bit TMR, use instruction cycle clock movlw 0x05 movwf CCP1CON,A ; set CCP1 to capture on every edge bcf PIR1,CCP1IF,A ; clear the CCP1IF flag edge1 btfss PIR1,CCP1IF,A ; wait for the first edge to arrive bra edge1 movff CCPR1H,PRODH movff CCPR1L,PRODL ; save the1st edge movff CCPR1L,PRODL bcf PIR1,CCP1IF,A ; clear the CCP1IF flag edge2 btfss PIR1,CCP1IF,A ; wait for the second edge to arrive bra edge2 clrf CCP1CON ; disable CCP1 capture movf PRODL,W,A subwf CCPR1L,W,A ; subtract first edge from 2nd edge movwf PRODL,A ; and leave the period in PRODH:PRODL movf PRODH,W,A subwfb CCPR1H,W,A movwf PRODH,A forever goto forever end Instruction cycle = 16MHz/4 = 4MHz = 2.5 x 10 -7 s = 250 ns Waveform = 1/ 2kHz = 5 x 10 -4 s 60% of duty cycle = (5 x 10 -4 ) x 0.6 = 3 x 10 -4 s No. of cycle = 3 x 10 -4 /2.5 x 10 -7 = 1200 40% of waveform = 2 x 10 -4 s No. of cycle = 2 x 10 -4 /2.5 x 10 -7 = 800 hi_lo equ 0xB0 ; number (1200) of clock cycles hi_hi equ 0x04 ; that signal is high lo_lo equ 0x20 ; number (800) of clock cycles lo_hi equ 0x03 ; that signal is low bcf TRISC, CCP1, A ; configure CCP1 for output movlw 0xC9 movwf T3CON ; configure TMR3 to 16 bit ; prescaler 1, TMR3 as time base, enable bcf PIR1, CCP1IF, A ; clear CCP1 flag bit movlw 0x09 ; load B’0000 1001’ to CCP1CON movwf CCP1CON ; CCP1 set high initially and pull low on match ; CCPR1=TMR3 + 1200 movlw hi_lo addwf TMR3L, W movwf CCPR1L movlw hi_hi addwfc TMR3H,W movwf CCPR1H bcf PIR1, CCP1IF, A ; clear CCP1 flag bit hi_time btfss PIR1, CCP1IF, A bra hi_time bcf PIR1, CCP1IF, A movlw 0x08 ; load B’0000 1000’ to CCP1CON movwf CCP1CON ; CCP1 set low initially and pull high on match ; CCPR1 =CCPR1 + 800 movlw lo_lo addwf CCPR1L, F movlw lo_hi addwfc CCPR1H, F lo_time btfss PIR1, CCP1IF, A bra lo_time bcf PIR1, CCP1IF, A movlw 0x09 movwf CCP1CON ; CCP1 set high initially and pull low on match movlw hi_lo addwf CCPR1L, F movlw hi_hi addwfc CCPR1H, F bra hi_time end
