I have found this code for the PIC microcontroller for digital temperature sensor, could you please help me? How do I compile this code and which software I can use it? Which programmer do you suggest me to upload this code to microcontroller. I am an engineering student I just started to study about assembly language. please advice me.
Thanks
LIST P=PIC16F628A
INCLUDE P16F628A.INC
__config _CP_OFF & DATA_CP_OFF & _LVP_OFF & _BODEN_OFF & _MCLRE_OFF & _PWRTE_ON & _WDT_OFF & _INTRC_OSC_NOCLKOUT
errorlevel -302 ;Eliminate bank warning
CBLOCK H'20'
HUNS ; Jump pointer for Hundreds digit
TENS ; Jump pointer for Tens digit
ONES ; Jump pointer for Ones digit
DECI ; Jump pointer for Decimal digit
THOU_COL ; 7 Segment Display Thousands Column, used within ISR
HUNS_COL ; 7 Segment Display Hundreds Column, used within ISR
TENS_COL ; 7 Segment Display Tens Column, used within ISR
ONES_COL ; 7 Segment Display Ones Column, used within ISR
COLSEL ; Stores COLUMN SELECT information
DIGIT ; Used for Indirect Addressing in Interrupt Service Routine
TEMPLO_C ; BS18B20 Celsius Temperature Result Low Byte
TEMPHI_C ; BS18B20 Celsius Temperature Result High Byte
COUNT ; For counting execution times in various routines
SHIFT ; For storing data to shift into and out of the DS18B20
DELAYGPR1 ; Used in delay subroutines
FLAGS ; -------X Unused
ENDC
W_ISR EQU H'70'
S_ISR EQU H'71'
P_ISR EQU H'72'
F_ISR EQU H'73'
ORG H'000' ; Processor reset vector location. On power up, the program jumps here
GOTO SETUP ;
ORG H'004' ; Interrupt vector location. When an Interupt occurs, the program jumps here
; (Thanks Mike, K8LH for help with this ISR routine. Contact via Electro-Tech-Online.com)
; Save
MOVWF W_ISR ; Save W to W_ISR
SWAPF STATUS, W ; Use SWAPF instruction so status bits don't change
MOVWF S_ISR ; Save Status to S_ISR
CLRF STATUS ; Switch to Bank 0
MOVF PCLATH, W ; Move PCLATH to W register
MOVWF P_ISR ; Save PCLATH to P_ISR
CLRF PCLATH ; Force page 0
MOVF FSR, W ; Move FSR to W register
MOVWF F_ISR ; Save FSR to F_ISR
; Refresh display
CLRF PORTB ; Blank the display
MOVF PORTA, W ; Move PORTA's current state to W
ANDLW B'11100000' ; Clear ONLY Column Select Bits & leave upper nibble unchanged
IORWF COLSEL, W ; Inclusive OR above with COLSEL register
MOVWF PORTA ; Leave upper nibble of PORTA unchanged & select new column
MOVF DIGIT, W ; Column number (DIGIT is initialised to 0. Used for Indirect Addressing)
ADDLW THOU_COL ; Add 'DIGIT' to 'THOU_COL' GPR address
MOVWF FSR ; FSR = THOU_COL + (0forTHOUS, 1forHUNS, 2forTENS & 3forONES) as they are in sequencial order in RAM
MOVF INDF, W ; W register now holds the jump pointer for the corresponding digit to be displayed
CALL SEGMENT_TABLE ; Get 7 segment arrangement from SEGMENT_TABLE for corresponding digit
BTFSC COLSEL, 1 ; Is TENS Column active
IORLW B'00000001' ; Yes, so activate TEN's column deciaml point
MOVWF PORTB ; NO, hide deciaml point and display new column
; Prepare for next column interrupt
INCF DIGIT, F ; Increment DIGIT jump pointer (used when indirect addressing above)
BCF STATUS, C ; Clear C bit of STATUS register
RRF COLSEL, F ; Advance column select bit
BTFSS STATUS,C ; Was that the last column? (or, Is Carry Flag Set?)
GOTO $+D'3' ; NO, do not reset DIGIT and COLumnSELect
CLRF DIGIT ; Reset DIGIT jump pointer
BSF COLSEL, 3 ; Reset column select to THOU_COL (1XXX) (00001000)
; RESTORE
BCF PIR1, TMR2IF ; Clear TMR2 interrupt flag while still in Bank 0
MOVF F_ISR, W ; MOVE F_ISR to W
MOVWF FSR ; Restore FSR
MOVF P_ISR, W ; MOVE P_ISR to W
MOVWF PCLATH ; Restore PCLATH
SWAPF S_ISR, W ; Undo previous SWAPF, place result in W
MOVWF STATUS ; Restore STATUS
SWAPF W_ISR, F ; Use SWAPF instruction so status bits don't change
SWAPF W_ISR, W ; Undo previous SWAPF and restore W register
RETFIE ; Return From Interrupt
; 7 Segment Display Arrangement Lookup
SEGMENT_TABLE ; This routine assigns on/off arrangement to the 7 Segment Display
ADDWF PCL, F
; BAFGEDCp JUMP B|A|F|G|E|D|C|p DISPLAY
RETLW B'11101110' ; 0 B|A|F|-|E|D|C|- 0
RETLW B'10000010' ; 1 B|-|-|-|-|-|C|- 1
RETLW B'11011100' ; 2 B|A|-|G|E|D|-|- 2
RETLW B'11010110' ; 3 B|A|-|G|-|D|C|- 3
RETLW B'10110010' ; 4 B|-|F|G|-|-|C|- 4
RETLW B'01110110' ; 5 -|A|F|G|-|D|C|- 5
RETLW B'01111110' ; 6 -|A|F|G|E|D|C|- 6
RETLW B'11000010' ; 7 B|A|-|-|-|-|C|- 7
RETLW B'11111110' ; 8 B|A|F|G|E|D|C|- 8
RETLW B'11110110' ; 9 B|A|F|G|-|D|C|- 9
RETLW B'00000000' ; 10 -|-|-|-|-|-|-|- BLANK
RETLW B'00010000' ; 11 -|-|-|G|-|-|-|- -
RETURN
; Program Orgiginates Here
SETUP ; This rountine sets up the Microcontroller's Inputs and Outputs
MOVLW H'07' ; Turn Comparators off and enable pins for I/O functions
MOVWF CMCON ;
BSF STATUS, RP0 ; Bank 1
MOVLW B'01010000' ; RA<7><5><3:0> Output, RA<6><4> Input
MOVWF TRISA ;
CLRF TRISB ; RB<7:0> Outputs
BCF STATUS, RP0 ; Bank 0
CLRF PORTA
CLRF PORTB
ONE_OFF_INITIALISE
; Clear ALL Bank 0 RAM from 0X20 - 0X7F (96 bytes)
BCF STATUS, IRP ; Indirect addressing Bank 0/1
MOVLW H'20' ; Initialise pointer to RAM
MOVWF FSR ; (File Select Register)
CLRF INDF ; Clear Register indirectly
INCF FSR, F ; Increment pointer
BTFSS FSR, 7 ; All done?
GOTO $-D'3' ; No, Clear next byte
; Initialise Column Select
BSF COLSEL, 3 ; Set column select to THOU_COL (1XXX) (00001000)
; Setup TMR2 for 0.0005s or 500uS Interrupts
CLRF TMR2 ; Clear TMR2 register
BSF STATUS, RP0 ; Bank 1
MOVLW B'00000010' ; 00000010
MOVWF PIE1 ; -------0 Disable TMR1IE - TMR1 Overflow Interrupt Enable bit
BCF STATUS, RP0 ; Bank 0
CLRF PIR1 ; Clear Peripheral Interrupt Flags
MOVLW B'00000001' ; 00000001
MOVWF T2CON ; ------01 Prescale 1:4
; -----0-- TMR2 OFF
; -0000--- Postscale 1:1
; 0------- Unused
BSF STATUS, RP0 ; Bank 1
MOVLW D'250' ;
MOVWF PR2 ; Interrupt every 0.001s or 1mS
BCF STATUS, RP0 ; Bank 0
BSF INTCON, GIE ; Enable Global Interrupts
BSF INTCON, PEIE ; Enable Peripheral Interrupts
BSF T2CON, TMR2ON ; Start TMR2
GOTO GET_TEMP
; Dallas DS18B20 Temperature Sensor 'One Wire' Communication Routines
DS18B20_RESET ; This routine Resets the DS18B20
CALL DQ_LL ; Force the DQ Line to Logic Low
MOVLW (D'480'-5)/5 ; Reset pulse must be held a minimum of 480uS.
CALL DELAY ; For delays from 10uS to 1285uS. Example, MOVLW D'10' for 10uS, MOVLW D'500' for 500uS. (D'n'-5)/5; n must be divisable by 5
CALL DQ_HIZ ; Release DQ Line
MOVLW (D'60'-5)/5 ; Wait for recovery
CALL DELAY ;
BTFSC PORTA, 4 ; Test for 'Presence Pulse'
GOTO DS18B20_RESET ; If not present, Reset
MOVLW (D'420'-5)/5 ; Must wait a minmum of 480uS from when DQ line is released before moving on
CALL DELAY ;
RETURN ;
DS18B20_READ_BYTE ; This routine reads a byte of data from the DS18B20
MOVLW H'08' ; Amount of bits to shift out
MOVWF COUNT ; Store in COUNT GPR
CALL DS18B20_READ_BIT ; Read bit
RRF SHIFT, F ; Rotate bit out of carry into SHIFT GPR
DECFSZ COUNT, F ; Decrement COUNT
GOTO $-D'3' ; If not zero, read next bit
MOVF SHIFT, W ; If zero, move SHIFT GPR to W
RETURN ;
DS18B20_READ_BIT ; This routine reads one bit of data from the DS18B20
BCF INTCON, GIE ; Disable Global Interrupts
CALL DQ_LL ; Force the DQ Line to Logic Low
CALL DQ_HIZ ; Release DQ Line
BSF STATUS, C ; Preset Carry Flag
BTFSS PORTA, 4 ; Test DQ Line
BCF STATUS, C ; If zero, Clear Carry Flag
BSF INTCON, GIE ; Enable Global Interrupts
MOVLW (D'60'-5)/5 ; Wait for Time Slot to end
CALL DELAY ;
RETURN ;
DS18B20_WRITE_BYTE ; This routine writes a byte of data to the DS18B20
MOVWF SHIFT ; Move data to shift into DS18B20 to SHIFT GPR
MOVLW D'08' ; Amount of bits to shift in
MOVWF COUNT ; Store in COUNT GPR
RRF SHIFT, F ; Rotate valid data into Carry Flag
CALL DS18B20_WRITE_BIT ; Write bit
DECFSZ COUNT, F ; Decrement COUNT
GOTO $-D'3' ; If not zero, read next bit
RETURN ; If zero, RETURN
DS18B20_WRITE_BIT ; This routine writes one bit of data to the DS18B20
BCF INTCON, GIE ; Disable Global Interrupts
CALL DQ_LL ; Force the DQ Line to Logic Low
BTFSS STATUS, C ; Test Carry Flag
GOTO $+D'2' ; If zero, leave DQ Line Logic Low
CALL DQ_HIZ ; If not zero, release DQ Line to Logic High
MOVLW (D'60'-5)/5 ; Hold Logic Low, write 0
CALL DELAY ;
CALL DQ_HIZ ; If not zero, release DQ Line to Logic High, write 1
BSF INTCON, GIE ; Enable Global Interrupts
RETURN ;
DQ_HIZ ; This routine forces the DQ Line to an Input / High Impedance state
BSF STATUS, RP0 ; Bank 1
BSF TRISA, 4 ; Make Pin 3 an input, Pullup resistor forces line to logic 1, unless DS18B20 pulls it low
BCF STATUS, RP0 ; Bank 0
RETURN
DQ_LL ; This routine forces the DQ Line to Logic Low
BCF PORTA, 4 ; Clear output latch
BSF STATUS, RP0 ; Bank 1
BCF TRISA, 4 ; Make Pin 3 an output
BCF STATUS, RP0 ; Bank 0
RETURN
DELAY ; This routine can provide delays from 10uS to 1285uS depending on the number moved to the Working register prior to calling the delay
MOVWF DELAYGPR1 ; Move integer to GPR
NOP ; No Operation
NOP ; No Operation
DECFSZ DELAYGPR1, F ; Decrement GPR and place back in itself
GOTO $-D'3' ; Not finished, GOTO here - 3 instructions
RETURN ; Finished, Return
GET_TEMP
CALL DS18B20_RESET ; Reset
MOVLW H'CC' ; Skiprom
CALL DS18B20_WRITE_BYTE ; Skiprom
MOVLW H'44' ; Convert T
CALL DS18B20_WRITE_BYTE ; Convert T
CALL DS18B20_READ_BIT ; Initiate Read Time Slots
BTFSS STATUS, C ; DS18B20 transmits a 0 while the temperature conversion is in progress and a 1 when the conversion is done
GOTO $-D'2' ; Transmitting 0 therefore NOT done
CALL DS18B20_RESET ; Reset
MOVLW H'CC' ; Skiprom
CALL DS18B20_WRITE_BYTE ; Skiprom
MOVLW H'BE' ; Read Scratchpad
CALL DS18B20_WRITE_BYTE ; Read Scratchpad
CALL DS18B20_READ_BYTE ; Move Scrachpad Byte 0 to W
MOVWF TEMPLO_C ; Store in Celsius TEMPLO GPR
CALL DS18B20_READ_BYTE ; Move Scrachpad Byte 1 to W
MOVWF TEMPHI_C ; Store in Celsius TEMPHI GPR
DISPLAY_TEMP
BCF FLAGS, 1 ; Clear Negative Flag
BTFSS TEMPHI_C, 7 ; Test if Temperature is negative (2's complement format)
GOTO REARRANGE_DATA ; NOT Negative, skip 'Undo 2's Complement'
BSF FLAGS, 1 ; Set Negative Flag; used later
; Example Negative Temperature TEMPHI = 1111 1110 TEMPLO = 0110 1110 = -25.1250 (see datasheet)
COMF TEMPLO_C, F ; Invert TEMPLO
COMF TEMPHI_C, F ; Invert TEMPHI
INCFSZ TEMPLO_C, F ; Increment TEMPLO once; After inverting the data, add one to acheive equivalent positive number (see 2's complement)
GOTO $+D'2' ; No overflow skip next instruction
INCF TEMPHI_C, F ; Overflow occured, increment upper byte
; Example Negative Temperature AFTER undo TEMPHI = 0000 0001 TEMPLO = 1001 0010 = +25.1250
REARRANGE_DATA ; This routine rearranges the 2 Temperature result bytes into useable data.
MOVLW B'11110000' ; W = 1111 0000
ANDWF TEMPLO_C, W ; F = 1001 0001 W = 1001 0000
IORWF TEMPHI_C, F ; F = 0000 0011 F = 1001 0011
SWAPF TEMPHI_C, F ; F = 1001 0011 F = 0011 1001 (New TEMPHI_C)
MOVLW B'00001111' ; W = 0000 1111
ANDWF TEMPLO_C, F ; F = 1001 0001 F = 0000 0001 (New TEMPLO_C)
BIN_TO_DEC_C ; This routine converts the 8-bit number held in TEMPHI_C to Decimal and stores it in 3 GPR's; HUNS, TENS & ONES
INCF TEMPHI_C ; Preload TEMPHI + 1
CLRF HUNS ; HUNS = 0000 0000
MOVLW D'246' ; MOVE Decimal'246' to W
MOVWF TENS ; TENS GPR = 1111 0101
MOVWF ONES ; ONES GPR = 1111 0101
DECFSZ TEMPHI_C, F ; Decement TEMPHI register
GOTO $+D'2' ; NOT 0, skip next instruction
GOTO $+D'7' ; IS 0, TEMPHI = 0000 0000, skip next 6 instructions and calculate how many tens and hundreds
INCFSZ ONES, F ; Increment ONES register, skip if 0
GOTO $-D'4' ; NOT 0, GOTO here - 4 instructions
INCFSZ TENS, F ; IS 0, Increment TENS register skip if 0
GOTO $-D'7' ; GOTO here - 7 instructions & reset the ONES register to D'246'
INCF HUNS, F ; TENS overflowed, Increment HUNS
GOTO $-D'10' ; GOTO here - 10 instructions & reset the ONES and TENS registers to D'246'
SUBWF TENS, F ; W still holds D'246 so subract it from TENS register to determine how many 'TENS'
SUBWF ONES, F ; W still holds D'246 so subract it from ONES register to determine how many 'ONES'
FRACTION_ROUND ; This routine rounds the fraction portion of the Temperature data to the nearest .1
; Provided by & used with his permission from 'Pommy'. Contact via Electro-Tech-Online.com
; Examples
; TENTHS = Fraction * 10 / 16
; TENTHS = 00000100 ( D'4' * 0.0625 = 0.2500 Degrees C) * 10 / 16 = 3
; TENTHS = 00001001 ( D'9' * 0.0625 = 0.5625 Degrees C) * 10 / 16 = 6
; TENTHS = 00001101 (D'13' * 0.0625 = 0.8125 Degrees C) * 10 / 16 = 8
MOVLW B'00001111' ;
ANDWF TEMPLO_C, F ;
MOVF TEMPLO_C, W ;
ADDWF TEMPLO_C, F ; *2, C=0
RLF TEMPLO_C, F ; *4, C=0
ADDWF TEMPLO_C, F ; *5, C=0
BTFSS STATUS, Z ; Does HUNS = not 0?
GOTO $+D'5' ; Yes, do not blank TENS
MOVF TENS, W ; MOVF instruction affects Z bit of STATUS register
BTFSC STATUS, Z ; Does TENS = 0?
MOVLW B'00001010' ; Yes, jump Pointer for blank arrangement
MOVWF TENS ;
BCF INTCON, GIE ; Disable Interrupts
MOVF HUNS, W
MOVWF THOU_COL
MOVF TENS, W
MOVWF HUNS_COL
MOVF ONES, W
MOVWF TENS_COL
MOVF DECI, W
MOVWF ONES_COL
BSF INTCON, GIE ; Enable Interrupts
GOTO GET_TEMP
END
Thanks
LIST P=PIC16F628A
INCLUDE P16F628A.INC
__config _CP_OFF & DATA_CP_OFF & _LVP_OFF & _BODEN_OFF & _MCLRE_OFF & _PWRTE_ON & _WDT_OFF & _INTRC_OSC_NOCLKOUT
errorlevel -302 ;Eliminate bank warning
CBLOCK H'20'
HUNS ; Jump pointer for Hundreds digit
TENS ; Jump pointer for Tens digit
ONES ; Jump pointer for Ones digit
DECI ; Jump pointer for Decimal digit
THOU_COL ; 7 Segment Display Thousands Column, used within ISR
HUNS_COL ; 7 Segment Display Hundreds Column, used within ISR
TENS_COL ; 7 Segment Display Tens Column, used within ISR
ONES_COL ; 7 Segment Display Ones Column, used within ISR
COLSEL ; Stores COLUMN SELECT information
DIGIT ; Used for Indirect Addressing in Interrupt Service Routine
TEMPLO_C ; BS18B20 Celsius Temperature Result Low Byte
TEMPHI_C ; BS18B20 Celsius Temperature Result High Byte
COUNT ; For counting execution times in various routines
SHIFT ; For storing data to shift into and out of the DS18B20
DELAYGPR1 ; Used in delay subroutines
FLAGS ; -------X Unused
ENDC
W_ISR EQU H'70'
S_ISR EQU H'71'
P_ISR EQU H'72'
F_ISR EQU H'73'
ORG H'000' ; Processor reset vector location. On power up, the program jumps here
GOTO SETUP ;
ORG H'004' ; Interrupt vector location. When an Interupt occurs, the program jumps here
; (Thanks Mike, K8LH for help with this ISR routine. Contact via Electro-Tech-Online.com)
; Save
MOVWF W_ISR ; Save W to W_ISR
SWAPF STATUS, W ; Use SWAPF instruction so status bits don't change
MOVWF S_ISR ; Save Status to S_ISR
CLRF STATUS ; Switch to Bank 0
MOVF PCLATH, W ; Move PCLATH to W register
MOVWF P_ISR ; Save PCLATH to P_ISR
CLRF PCLATH ; Force page 0
MOVF FSR, W ; Move FSR to W register
MOVWF F_ISR ; Save FSR to F_ISR
; Refresh display
CLRF PORTB ; Blank the display
MOVF PORTA, W ; Move PORTA's current state to W
ANDLW B'11100000' ; Clear ONLY Column Select Bits & leave upper nibble unchanged
IORWF COLSEL, W ; Inclusive OR above with COLSEL register
MOVWF PORTA ; Leave upper nibble of PORTA unchanged & select new column
MOVF DIGIT, W ; Column number (DIGIT is initialised to 0. Used for Indirect Addressing)
ADDLW THOU_COL ; Add 'DIGIT' to 'THOU_COL' GPR address
MOVWF FSR ; FSR = THOU_COL + (0forTHOUS, 1forHUNS, 2forTENS & 3forONES) as they are in sequencial order in RAM
MOVF INDF, W ; W register now holds the jump pointer for the corresponding digit to be displayed
CALL SEGMENT_TABLE ; Get 7 segment arrangement from SEGMENT_TABLE for corresponding digit
BTFSC COLSEL, 1 ; Is TENS Column active
IORLW B'00000001' ; Yes, so activate TEN's column deciaml point
MOVWF PORTB ; NO, hide deciaml point and display new column
; Prepare for next column interrupt
INCF DIGIT, F ; Increment DIGIT jump pointer (used when indirect addressing above)
BCF STATUS, C ; Clear C bit of STATUS register
RRF COLSEL, F ; Advance column select bit
BTFSS STATUS,C ; Was that the last column? (or, Is Carry Flag Set?)
GOTO $+D'3' ; NO, do not reset DIGIT and COLumnSELect
CLRF DIGIT ; Reset DIGIT jump pointer
BSF COLSEL, 3 ; Reset column select to THOU_COL (1XXX) (00001000)
; RESTORE
BCF PIR1, TMR2IF ; Clear TMR2 interrupt flag while still in Bank 0
MOVF F_ISR, W ; MOVE F_ISR to W
MOVWF FSR ; Restore FSR
MOVF P_ISR, W ; MOVE P_ISR to W
MOVWF PCLATH ; Restore PCLATH
SWAPF S_ISR, W ; Undo previous SWAPF, place result in W
MOVWF STATUS ; Restore STATUS
SWAPF W_ISR, F ; Use SWAPF instruction so status bits don't change
SWAPF W_ISR, W ; Undo previous SWAPF and restore W register
RETFIE ; Return From Interrupt
; 7 Segment Display Arrangement Lookup
SEGMENT_TABLE ; This routine assigns on/off arrangement to the 7 Segment Display
ADDWF PCL, F
; BAFGEDCp JUMP B|A|F|G|E|D|C|p DISPLAY
RETLW B'11101110' ; 0 B|A|F|-|E|D|C|- 0
RETLW B'10000010' ; 1 B|-|-|-|-|-|C|- 1
RETLW B'11011100' ; 2 B|A|-|G|E|D|-|- 2
RETLW B'11010110' ; 3 B|A|-|G|-|D|C|- 3
RETLW B'10110010' ; 4 B|-|F|G|-|-|C|- 4
RETLW B'01110110' ; 5 -|A|F|G|-|D|C|- 5
RETLW B'01111110' ; 6 -|A|F|G|E|D|C|- 6
RETLW B'11000010' ; 7 B|A|-|-|-|-|C|- 7
RETLW B'11111110' ; 8 B|A|F|G|E|D|C|- 8
RETLW B'11110110' ; 9 B|A|F|G|-|D|C|- 9
RETLW B'00000000' ; 10 -|-|-|-|-|-|-|- BLANK
RETLW B'00010000' ; 11 -|-|-|G|-|-|-|- -
RETURN
; Program Orgiginates Here
SETUP ; This rountine sets up the Microcontroller's Inputs and Outputs
MOVLW H'07' ; Turn Comparators off and enable pins for I/O functions
MOVWF CMCON ;
BSF STATUS, RP0 ; Bank 1
MOVLW B'01010000' ; RA<7><5><3:0> Output, RA<6><4> Input
MOVWF TRISA ;
CLRF TRISB ; RB<7:0> Outputs
BCF STATUS, RP0 ; Bank 0
CLRF PORTA
CLRF PORTB
ONE_OFF_INITIALISE
; Clear ALL Bank 0 RAM from 0X20 - 0X7F (96 bytes)
BCF STATUS, IRP ; Indirect addressing Bank 0/1
MOVLW H'20' ; Initialise pointer to RAM
MOVWF FSR ; (File Select Register)
CLRF INDF ; Clear Register indirectly
INCF FSR, F ; Increment pointer
BTFSS FSR, 7 ; All done?
GOTO $-D'3' ; No, Clear next byte
; Initialise Column Select
BSF COLSEL, 3 ; Set column select to THOU_COL (1XXX) (00001000)
; Setup TMR2 for 0.0005s or 500uS Interrupts
CLRF TMR2 ; Clear TMR2 register
BSF STATUS, RP0 ; Bank 1
MOVLW B'00000010' ; 00000010
MOVWF PIE1 ; -------0 Disable TMR1IE - TMR1 Overflow Interrupt Enable bit
BCF STATUS, RP0 ; Bank 0
CLRF PIR1 ; Clear Peripheral Interrupt Flags
MOVLW B'00000001' ; 00000001
MOVWF T2CON ; ------01 Prescale 1:4
; -----0-- TMR2 OFF
; -0000--- Postscale 1:1
; 0------- Unused
BSF STATUS, RP0 ; Bank 1
MOVLW D'250' ;
MOVWF PR2 ; Interrupt every 0.001s or 1mS
BCF STATUS, RP0 ; Bank 0
BSF INTCON, GIE ; Enable Global Interrupts
BSF INTCON, PEIE ; Enable Peripheral Interrupts
BSF T2CON, TMR2ON ; Start TMR2
GOTO GET_TEMP
; Dallas DS18B20 Temperature Sensor 'One Wire' Communication Routines
DS18B20_RESET ; This routine Resets the DS18B20
CALL DQ_LL ; Force the DQ Line to Logic Low
MOVLW (D'480'-5)/5 ; Reset pulse must be held a minimum of 480uS.
CALL DELAY ; For delays from 10uS to 1285uS. Example, MOVLW D'10' for 10uS, MOVLW D'500' for 500uS. (D'n'-5)/5; n must be divisable by 5
CALL DQ_HIZ ; Release DQ Line
MOVLW (D'60'-5)/5 ; Wait for recovery
CALL DELAY ;
BTFSC PORTA, 4 ; Test for 'Presence Pulse'
GOTO DS18B20_RESET ; If not present, Reset
MOVLW (D'420'-5)/5 ; Must wait a minmum of 480uS from when DQ line is released before moving on
CALL DELAY ;
RETURN ;
DS18B20_READ_BYTE ; This routine reads a byte of data from the DS18B20
MOVLW H'08' ; Amount of bits to shift out
MOVWF COUNT ; Store in COUNT GPR
CALL DS18B20_READ_BIT ; Read bit
RRF SHIFT, F ; Rotate bit out of carry into SHIFT GPR
DECFSZ COUNT, F ; Decrement COUNT
GOTO $-D'3' ; If not zero, read next bit
MOVF SHIFT, W ; If zero, move SHIFT GPR to W
RETURN ;
DS18B20_READ_BIT ; This routine reads one bit of data from the DS18B20
BCF INTCON, GIE ; Disable Global Interrupts
CALL DQ_LL ; Force the DQ Line to Logic Low
CALL DQ_HIZ ; Release DQ Line
BSF STATUS, C ; Preset Carry Flag
BTFSS PORTA, 4 ; Test DQ Line
BCF STATUS, C ; If zero, Clear Carry Flag
BSF INTCON, GIE ; Enable Global Interrupts
MOVLW (D'60'-5)/5 ; Wait for Time Slot to end
CALL DELAY ;
RETURN ;
DS18B20_WRITE_BYTE ; This routine writes a byte of data to the DS18B20
MOVWF SHIFT ; Move data to shift into DS18B20 to SHIFT GPR
MOVLW D'08' ; Amount of bits to shift in
MOVWF COUNT ; Store in COUNT GPR
RRF SHIFT, F ; Rotate valid data into Carry Flag
CALL DS18B20_WRITE_BIT ; Write bit
DECFSZ COUNT, F ; Decrement COUNT
GOTO $-D'3' ; If not zero, read next bit
RETURN ; If zero, RETURN
DS18B20_WRITE_BIT ; This routine writes one bit of data to the DS18B20
BCF INTCON, GIE ; Disable Global Interrupts
CALL DQ_LL ; Force the DQ Line to Logic Low
BTFSS STATUS, C ; Test Carry Flag
GOTO $+D'2' ; If zero, leave DQ Line Logic Low
CALL DQ_HIZ ; If not zero, release DQ Line to Logic High
MOVLW (D'60'-5)/5 ; Hold Logic Low, write 0
CALL DELAY ;
CALL DQ_HIZ ; If not zero, release DQ Line to Logic High, write 1
BSF INTCON, GIE ; Enable Global Interrupts
RETURN ;
DQ_HIZ ; This routine forces the DQ Line to an Input / High Impedance state
BSF STATUS, RP0 ; Bank 1
BSF TRISA, 4 ; Make Pin 3 an input, Pullup resistor forces line to logic 1, unless DS18B20 pulls it low
BCF STATUS, RP0 ; Bank 0
RETURN
DQ_LL ; This routine forces the DQ Line to Logic Low
BCF PORTA, 4 ; Clear output latch
BSF STATUS, RP0 ; Bank 1
BCF TRISA, 4 ; Make Pin 3 an output
BCF STATUS, RP0 ; Bank 0
RETURN
DELAY ; This routine can provide delays from 10uS to 1285uS depending on the number moved to the Working register prior to calling the delay
MOVWF DELAYGPR1 ; Move integer to GPR
NOP ; No Operation
NOP ; No Operation
DECFSZ DELAYGPR1, F ; Decrement GPR and place back in itself
GOTO $-D'3' ; Not finished, GOTO here - 3 instructions
RETURN ; Finished, Return
GET_TEMP
CALL DS18B20_RESET ; Reset
MOVLW H'CC' ; Skiprom
CALL DS18B20_WRITE_BYTE ; Skiprom
MOVLW H'44' ; Convert T
CALL DS18B20_WRITE_BYTE ; Convert T
CALL DS18B20_READ_BIT ; Initiate Read Time Slots
BTFSS STATUS, C ; DS18B20 transmits a 0 while the temperature conversion is in progress and a 1 when the conversion is done
GOTO $-D'2' ; Transmitting 0 therefore NOT done
CALL DS18B20_RESET ; Reset
MOVLW H'CC' ; Skiprom
CALL DS18B20_WRITE_BYTE ; Skiprom
MOVLW H'BE' ; Read Scratchpad
CALL DS18B20_WRITE_BYTE ; Read Scratchpad
CALL DS18B20_READ_BYTE ; Move Scrachpad Byte 0 to W
MOVWF TEMPLO_C ; Store in Celsius TEMPLO GPR
CALL DS18B20_READ_BYTE ; Move Scrachpad Byte 1 to W
MOVWF TEMPHI_C ; Store in Celsius TEMPHI GPR
DISPLAY_TEMP
BCF FLAGS, 1 ; Clear Negative Flag
BTFSS TEMPHI_C, 7 ; Test if Temperature is negative (2's complement format)
GOTO REARRANGE_DATA ; NOT Negative, skip 'Undo 2's Complement'
BSF FLAGS, 1 ; Set Negative Flag; used later
; Example Negative Temperature TEMPHI = 1111 1110 TEMPLO = 0110 1110 = -25.1250 (see datasheet)
COMF TEMPLO_C, F ; Invert TEMPLO
COMF TEMPHI_C, F ; Invert TEMPHI
INCFSZ TEMPLO_C, F ; Increment TEMPLO once; After inverting the data, add one to acheive equivalent positive number (see 2's complement)
GOTO $+D'2' ; No overflow skip next instruction
INCF TEMPHI_C, F ; Overflow occured, increment upper byte
; Example Negative Temperature AFTER undo TEMPHI = 0000 0001 TEMPLO = 1001 0010 = +25.1250
REARRANGE_DATA ; This routine rearranges the 2 Temperature result bytes into useable data.
MOVLW B'11110000' ; W = 1111 0000
ANDWF TEMPLO_C, W ; F = 1001 0001 W = 1001 0000
IORWF TEMPHI_C, F ; F = 0000 0011 F = 1001 0011
SWAPF TEMPHI_C, F ; F = 1001 0011 F = 0011 1001 (New TEMPHI_C)
MOVLW B'00001111' ; W = 0000 1111
ANDWF TEMPLO_C, F ; F = 1001 0001 F = 0000 0001 (New TEMPLO_C)
BIN_TO_DEC_C ; This routine converts the 8-bit number held in TEMPHI_C to Decimal and stores it in 3 GPR's; HUNS, TENS & ONES
INCF TEMPHI_C ; Preload TEMPHI + 1
CLRF HUNS ; HUNS = 0000 0000
MOVLW D'246' ; MOVE Decimal'246' to W
MOVWF TENS ; TENS GPR = 1111 0101
MOVWF ONES ; ONES GPR = 1111 0101
DECFSZ TEMPHI_C, F ; Decement TEMPHI register
GOTO $+D'2' ; NOT 0, skip next instruction
GOTO $+D'7' ; IS 0, TEMPHI = 0000 0000, skip next 6 instructions and calculate how many tens and hundreds
INCFSZ ONES, F ; Increment ONES register, skip if 0
GOTO $-D'4' ; NOT 0, GOTO here - 4 instructions
INCFSZ TENS, F ; IS 0, Increment TENS register skip if 0
GOTO $-D'7' ; GOTO here - 7 instructions & reset the ONES register to D'246'
INCF HUNS, F ; TENS overflowed, Increment HUNS
GOTO $-D'10' ; GOTO here - 10 instructions & reset the ONES and TENS registers to D'246'
SUBWF TENS, F ; W still holds D'246 so subract it from TENS register to determine how many 'TENS'
SUBWF ONES, F ; W still holds D'246 so subract it from ONES register to determine how many 'ONES'
FRACTION_ROUND ; This routine rounds the fraction portion of the Temperature data to the nearest .1
; Provided by & used with his permission from 'Pommy'. Contact via Electro-Tech-Online.com
; Examples
; TENTHS = Fraction * 10 / 16
; TENTHS = 00000100 ( D'4' * 0.0625 = 0.2500 Degrees C) * 10 / 16 = 3
; TENTHS = 00001001 ( D'9' * 0.0625 = 0.5625 Degrees C) * 10 / 16 = 6
; TENTHS = 00001101 (D'13' * 0.0625 = 0.8125 Degrees C) * 10 / 16 = 8
MOVLW B'00001111' ;
ANDWF TEMPLO_C, F ;
MOVF TEMPLO_C, W ;
ADDWF TEMPLO_C, F ; *2, C=0
RLF TEMPLO_C, F ; *4, C=0
ADDWF TEMPLO_C, F ; *5, C=0
BTFSS STATUS, Z ; Does HUNS = not 0?
GOTO $+D'5' ; Yes, do not blank TENS
MOVF TENS, W ; MOVF instruction affects Z bit of STATUS register
BTFSC STATUS, Z ; Does TENS = 0?
MOVLW B'00001010' ; Yes, jump Pointer for blank arrangement
MOVWF TENS ;
BCF INTCON, GIE ; Disable Interrupts
MOVF HUNS, W
MOVWF THOU_COL
MOVF TENS, W
MOVWF HUNS_COL
MOVF ONES, W
MOVWF TENS_COL
MOVF DECI, W
MOVWF ONES_COL
BSF INTCON, GIE ; Enable Interrupts
GOTO GET_TEMP
END
