[Menu]>[Guide to use the PIC]>[Circuits Gallery]>[Ultrasonic Range Meter]
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;
; Ultrasonic Range Meter
;
; Device : PIC16F873
; Author : Seiichi Inoue
;********************************************************
list p=pic16f873
include p16f873.inc
__config _hs_osc & _wdt_off & _pwrte_on & _lvp_off
;**************** Label Definition ********************
cblock h'20'
s_count ;Send-out pulse count adr
s_adj ;Adjustment data address
s_adj_count ;Rotate value save adr
s_digit ;Digit cont work address
g_time1 ;Guard timer address 1
g_time2 ;Guard timer address 2
p_countl ;Propagation L cnt adr
p_counth ;Propagation H cnt adr
digit_cnt ;Digit counter head adr
disp_ha ;Digit head address
disp_u ;1st digit address
disp_t ;10th digit address
disp_h ;100th digit address
seg7_ha ;7 segLED table head adr
seg70 ;Pattern 0 set adr
seg71 ;Pattern 1 set adr
seg72 ;Pattern 2 set adr
seg73 ;Pattern 3 set adr
seg74 ;Pattern 4 set adr
seg75 ;Pattern 5 set adr
seg76 ;Pattern 6 set adr
seg77 ;Pattern 7 set adr
seg78 ;Pattern 8 set adr
seg79 ;Pattern 9 set adr
seg7a ;Pattern A set adr
seg7b ;Pattern B set adr
endc
ra1 equ h'01' ;RA1 port designation
ra2 equ h'02' ;RA2 port designation
ra3 equ h'03' ;RA3 port designation
ra5 equ h'05' ;RA5 port designation
ccp1 equ h'02' ;CCP1(RC2) designation
seg7_0 equ b'01000000' ;-gfedcba Pattern 0
seg7_1 equ b'01111001' ; Pattern 1
seg7_2 equ b'00100100' ; Pattern 2
seg7_3 equ b'00110000' ; Pattern 3
seg7_4 equ b'00011001' ; Pattern 4
seg7_5 equ b'00010010' ; Pattern 5
seg7_6 equ b'00000010' ; Pattern 6
seg7_7 equ b'01111000' ; Pattern 7
seg7_8 equ b'00000000' ; Pattern 8
seg7_9 equ b'00010000' ; Pattern 9
seg7_a equ b'01111111' ; Detect error
seg7_b equ b'00100011' ; Illegal int
;**************** Program Start ***********************
org 0 ;Reset Vector
goto init
org 4 ;Interrupt Vector
goto int
;**************** Initial Process *********************
init
;*** Port initialization
bsf status,rp0 ;Change to Bank1
movlw b'00000001' ;AN0 to input mode
movwf trisa ;Set TRISA register
clrf trisb ;RB port to output mode
movlw b'00000100' ;RC2/CCP1 to input mode
movwf trisc ;Set TRISC register
;*** Ultrasonic sending period initialization (Timer0)
movlw b'11010111' ;T0CS=0,PSA=0,PS=1:256
movwf option_reg ;Set OPTION_REG register
bcf status,rp0 ;Change to Bank0
clrf tmr0 ;Clear TMR0 register
;*** Capture mode initialization (Timer1)
movlw b'00000001' ;Pre=1:1 TMR1=Int TMR1=ON
movwf t1con ;Set T1CON register
clrf ccp1con ;CCP1 off
;*** A/D converter initialization
movlw b'01000001' ;ADCS=01 CHS=AN0 ADON=ON
movwf adcon0 ;Set ADCON0 register
bsf status,rp0 ;Change to Bank1
movlw b'00001110' ;ADFM=0 PCFG=1110
movwf adcon1 ;Set ADCON1 register
bcf status,rp0 ;Change to Bank0
;*** Display initialization (Timer2)
movlw disp_u ;Set digit head address
movwf disp_ha ;Save digit head sddress
movlw h'0a' ;"Detect error" data
movwf disp_u ;Set 1st digit
movwf disp_t ;Set 10th digit
movwf disp_h ;Set 100th digit
movlw d'3' ;Digit counter
movwf digit_cnt ;Set digit counter
movlw seg70 ;Set 7seg head address
movwf seg7_ha ;Save 7seg head address
movlw seg7_0 ;Set 7segment pattern 0
movwf seg70 ;Save pattern 0
movlw seg7_1 ;Set 7segment pattern 1
movwf seg71 ;Save pattern 1
movlw seg7_2 ;Set 7segment pattern 2
movwf seg72 ;Save pattern 2
movlw seg7_3 ;Set 7segment pattern 3
movwf seg73 ;Save pattern 3
movlw seg7_4 ;Set 7segment pattern 4
movwf seg74 ;Save pattern 4
movlw seg7_5 ;Set 7segment pattern 5
movwf seg75 ;Save pattern 5
movlw seg7_6 ;Set 7segment pattern 6
movwf seg76 ;Save pattern 6
movlw seg7_7 ;Set 7segment pattern 7
movwf seg77 ;Save pattern 7
movlw seg7_8 ;Set 7segment pattern 8
movwf seg78 ;Save pattern 8
movlw seg7_9 ;Set 7segment pattern 9
movwf seg79 ;Save pattern 9
movlw seg7_a ;Set 7segment pattern A
movwf seg7a ;Save pattern A
movlw seg7_b ;Set 7segment pattern B
movwf seg7b ;Save pattern B
movlw b'00011110' ;OPS=1:4,T2=ON,EPS=1:16
movwf t2con ;Set T2CON register
bsf status,rp0 ;Change to Bank1
movlw d'157' ;157x64=10048usec
movwf pr2 ;Set PR2 register
bsf pie1,tmr2ie ;TMR2IE=ON
bcf status,rp0 ;Change to Bank0
;*** Interruption control
movlw b'11100000' ;GIE=ON,PEIE=ON,T0IE=ON
movwf intcon ;Set INTCON register
wait
goto $ ;Interruption wait
;*************** Interruption Process *****************
int
movfw pir1 ;Read PIR1 register
btfsc pir1,ccp1if ;Capture occurred ?
goto capture ;Yes. "Capture"
btfsc pir1,tmr2if ;TMR2 time out ?
goto led_cont ;Yes. "LED display"
movfw intcon ;Read INTCON register
btfsc intcon,t0if ;TMR0 time out ?
goto send ;Yes. "Pulse send"
;*************** Illegal interruption *****************
illegal
movlw h'0b' ;Set Illegal disp digit
addwf seg7_ha,w ;Seg7 H.Adr + digit
movwf fsr ;Set FSR register
movfw indf ;Read seg7 data
movwf portb ;Write LED data
bcf porta,ra1 ;RA1=ON
bcf porta,ra2 ;RA2=ON
bcf porta,ra3 ;RA3=ON
goto $ ;Stop
;************ END of Interruption Process **************
int_end
retfie
;*************** Pulse send-out Process ****************
send
bcf intcon,t0if ;Clear TMR0 int flag
clrf tmr0 ;Timer0 clear
;*** Received Pulse detection check
movfw portc ;Read PORTC register
btfsc portc,ccp1 ;Detected ?
goto detect_off ;Yes. Detected
movlw h'0a' ;"Detect error" data
movwf disp_u ;Set 1st digit
movwf disp_t ;Set 10th digit
movwf disp_h ;Set 100th digit
;*** Receive pulse detector off
detect_off
bcf porta,ra5 ;Set detector OFF
;*** Capture start
clrf tmr1h ;Clear TMR1H register
clrf tmr1l ;Clear TMR1L register
clrf ccpr1h ;Clear CCPR1H register
clrf ccpr1l ;Clear CCPR1L register
movlw b'00000101' ;CCP1M=0101(Capture)
movwf ccp1con ;Set CCP1CON register
bsf status,rp0 ;Change to Bank1
bsf pie1,ccp1ie ;CCP1 interruptin enable
bcf status,rp0 ;Change to Bank0
bcf pir1,ccp1if ;Clear CCP1 int flag
;*** 40KHz pulse send ( 0.5 msec )
movlw d'20' ;Send-out pulse count
movwf s_count ;Set count
s_loop
call pulse ;Call pulse send sub
decfsz s_count,f ;End ?
goto s_loop ;No. Continue
;*** Get adjustment data
bsf adcon0,go ;Start A/D convert
ad_check
btfsc adcon0,go ;A/D convert end ?
goto ad_check ;No. Again
movfw adresh ;Read ADRESH register
movwf s_adj ;Save converted data
movlw d'5' ;Set rotate value
movwf s_adj_count ;Save rotate value
ad_rotate
rrf s_adj,f ;Rotate right 1 bit
decfsz s_adj_count,f ;End ?
goto ad_rotate ;No. Continue
movfw s_adj ;Read rotated value
andlw b'00000111' ;Pick-up 3 bits
addlw d'54' ;(0 to 7) + 54 = 54 to 61
movwf s_adj ;Save adjustment data
;*** Capture guard timer ( 1 milisecound )
movlw d'2' ;Set loop counter1
movwf g_time1 ;Save loop counter1
g_loop1 movlw d'124' ;Set loop counter2
movwf g_time2 ;Save loop counter2
g_loop2 nop ;Time adjust
decfsz g_time2,f ;g_time2 - 1 = 0 ?
goto g_loop2 ;No. Continue
decfsz g_time1,f ;g_time1 - 1 = 0 ?
goto g_loop1 ;No. Continue
;*** Receive pulse detector on
bsf porta,ra5 ;Set detector ON
goto int_end
;*************** Pulse send-out Process ****************
pulse
movlw b'00010000' ;RC4=ON
movwf portc ;Set PORTC register
call t12us ;Call 12usec timer
clrf portc ;RC4=OFF
goto $+1
goto $+1
nop
return
;*************** 12 microseconds timer *****************
t12us
goto $+1
goto $+1
goto $+1
goto $+1
nop
return
;****************** Capture Process ********************
capture
bcf pir1,ccp1if ;Clear CCP1 int flag
clrf p_countl ;Clear L count
clrf p_counth ;Clear H count
clrf ccp1con ;CCP1 off
division
movfw s_adj ;Read adjustment data
subwf ccpr1l,f ;Capture - adjust
btfsc status,z ;Result = 0 ?
goto division2 ;Yes. "R = 0"
btfsc status,c ;Result < 0 ?
goto division1 ;No. "R > 0"
goto division3 ;Yes."R < 0"
division1 ;( R > 0 )
movlw d'1' ;Set increment value
addwf p_countl,f ;Increment L count
btfss status,c ;Overflow ?
goto division ;No. Continue
incf p_counth,f ;Increment H count
goto division ;Jump next
division2 ;( R = 0 )
movfw ccpr1h ;Read CCPR1H
btfss status,z ;CCPR1H = 0 ?
goto division1 ;No. Next
movlw d'1' ;Set increment value
addwf p_countl,f ;Increment L count
btfss status,c ;Overflow ?
goto digit_set ;Jump to digit set
incf p_counth,f ;Increment H count
goto digit_set ;Jump to digit set
division3 ;( R < 0 )
movfw ccpr1h ;Read CCPR1H
btfss status,z ;CCPR1H = 0 ?
goto division4 ;No. Borrow process
goto digit_set ;Jump to digit set
division4
decf ccpr1h,f ;CCPR1H - 1
movlw d'255' ;Borrow value
addwf ccpr1l,f ;CCPR1L + 255
incf ccpr1l,f ;CCPR1L + 1
goto division1 ;Next
;**************** Digit Set Process ********************
digit_set
clrf disp_u ;Clear 1st digit
clrf disp_t ;Clear 10th digit
clrf disp_h ;Clear 100th digit
;*** 100th digit
digit_h
movlw d'100' ;Divide value
subwf p_countl,f ;Digit - divide
btfsc status,z ;Result = 0 ?
goto digit_h2 ;Yes. "R = 0"
btfsc status,c ;Result < 0 ?
goto digit_h1 ;No. "R > 0"
goto digit_h3 ;Yes."R < 0"
digit_h1 ;( R > 0 )
incf disp_h,f ;Increment 100th count
goto digit_h ;Jump next
digit_h2 ;( R = 0 )
movfw p_counth ;Read H counter
btfss status,z ;H counter = 0 ?
goto digit_h1 ;No. Next
incf disp_h,f ;Increment 100th count
goto digit_t ;Jump to 10th digit pro
digit_h3 ;( R < 0 )
movfw p_counth ;Read H counter
btfss status,z ;H counter = 0 ?
goto digit_h4 ;No. Borrow process
movlw d'100' ;Divide value
addwf p_countl,f ;Return over sub value
goto digit_t ;Jump to 10th digit pro
digit_h4
decf p_counth,f ;H counter - 1
movlw d'255' ;Borrow value
addwf p_countl,f ;L counter + 255
incf p_countl,f ;L counter + 1
goto digit_h1 ;Next
;*** 10th digit
digit_t
;*** Range over check
movfw disp_h ;Read 100th digit
sublw d'9' ;9 - (100th digit)
btfsc status,z ;Result = 0 ?
goto digit_t0 ;Yes. "R = 0"
btfsc status,c ;Result < 0 ?
goto digit_t0 ;No. "R > 0"
movlw h'0a' ;"Detect error" data
movwf disp_u ;Set 1st digit
movwf disp_t ;Set 10th digit
movwf disp_h ;Set 100th digit
goto int_end
digit_t0
movlw d'10' ;Divide value
subwf p_countl,f ;Digit - divide
btfsc status,z ;Result = 0 ?
goto digit_t1 ;Yes. "R = 0"
btfsc status,c ;Result < 0 ?
goto digit_t1 ;No. "R > 0"
goto digit_t2 ;Yes."R < 0"
digit_t1 ;( R >= 0 )
incf disp_t,f ;Increment 10th count
goto digit_t ;Jump next
digit_t2 ;( R < 0 )
movlw d'10' ;Divide value
addwf p_countl,f ;Return over sub value
goto digit_u ;Jump to 1st digit pro
;*** 1st digit
digit_u
movfw p_countl ;Read propagetion counter
movwf disp_u ;Save 1st count
goto int_end
;**************** LED display control *****************
led_cont
bcf pir1,tmr2if ;Clear TMR2 int flag
movfw digit_cnt ;Read digit counter
movwf s_digit ;Save digit counter
decfsz s_digit,f ;1st digit ?
goto d_check1 ;No. Next
bsf porta,ra1 ;RA1=OFF
bsf porta,ra2 ;RA2=OFF
bcf porta,ra3 ;RA3=ON
goto c_digit ;Jump to digit cont
d_check1
decfsz s_digit,f ;10th digit ?
goto d_check2 ;No. 100th digit
bsf porta,ra1 ;RA1=OFF
bcf porta,ra2 ;RA2=ON
bsf porta,ra3 ;RA3=OFF
goto c_digit ;Jump to digit cont
d_check2
bcf porta,ra1 ;RA1=ON
bsf porta,ra2 ;RA2=OFF
bsf porta,ra3 ;RA3=OFF
c_digit
decf digit_cnt,w ;Digit count - 1
addwf disp_ha,w ;Digit H.Adr + count
movwf fsr ;Set FSR register
movfw indf ;Read digit
addwf seg7_ha,w ;Seg7 H.Adr + digit
movwf fsr ;Set FSR register
movfw indf ;Read seg7 data
movwf portb ;Write LED data
decfsz digit_cnt,f ;Digit count - 1
goto int_end ;Jump to interrupt end
movlw d'3' ;Initial value
movwf digit_cnt ;Set initial value
goto int_end ;Jump to interrupt end
;********************************************************
; END of Ultrasonic Range Meter
;********************************************************
end |
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