code [code@mxhub.net] says:
I have written a asm recently for reading temperature with [the Dallas] ds18s20 and putting it out to a LCD. You might find some help in it
LIST P=16F84A ; 16F84A Runs at 10 MHz
INCLUDE "p16f84a.inc"
__CONFIG _PWRTE_ON & _HS_OSC & _WDT_OFF ; uses 10 MHz crystal
ERRORLEVEL -224 ; supress annoying message from tris
ERRORLEVEL -302 ; supress message from page change
; Define Information
#DEFINE RS PORTA, 0 ; RA0 is RS line of LCD
#DEFINE E PORTA, 1 ; RA1 is E line of LCD
CONSTANT DATA_PIN=4
CONSTANT BASE_VAR=0C
CONSTANT DATA_BUFF=28H
CONSTANT BUFF_SIZE=7
N EQU BASE_VAR+0
INDEX EQU BASE_VAR+1 ; these vars used by the
O_BYTE EQU BASE_VAR+2 ; common 1-wire routines
I_BYTE EQU BASE_VAR+3
TEMP EQU BASE_VAR+4
LOOP1 EQU BASE_VAR+5 ; used for timing
TEMP_1 EQU BASE_VAR+6 ; used for calculating CRC
DATA_BIT EQU BASE_VAR+7
SHIFT_REG EQU BASE_VAR+8
FB EQU BASE_VAR+9
TEMP_MSB EQU DATA_BUFF+0 ; first location in DATA_BUFF
TEMP_LSB EQU DATA_BUFF+1
TH_R EQU DATA_BUFF+2
TL_R EQU DATA_BUFF+3
COUNTREMAIN EQU DATA_BUFF+4
COUNTPERC EQU DATA_BUFF+5
CRC EQU DATA_BUFF+6
; Macro
EStrobe MACRO ; Strobe the "E" Bit
bsf E
bcf E
ENDM
CBLOCK 0CH
countdown ;
Temp ; a temporary variable
count ; counter
cntmsec ; used in counting milliseconds
bin ; binary number to be converted to BCD
hundreds ; BCD hundreds result
tens_and_ones ; BCD tens and ones result
ENDC
ORG 0 ; start at location 0
goto MAIN ; jump over to main routine
;----------------------------------------------------------------------;
; Initialize the ports ;
;----------------------------------------------------------------------;
Init:
clrf PORTA
clrf PORTB
movlw B'00011100' ; RA4, RA2 input, others outputs
tris PORTA
movlw B'00110000' ; RB4, RB5 input, others outputs
tris PORTB
movlw B'00100011' ; pull-ups enabled
; prescaler assigned to RA4
; prescaler set to 1:16
option
return
;----------------------------------------------------------------------;
; Initialize the LCD ;
;----------------------------------------------------------------------;
initlcd:
movlw D'40'
call nmsec ; Wait 40 msecs before Reset
bcf RS ; send an 8 bit instruction
movlw 0x03 ; Reset Command
call NybbleOut ; Send the Nybble
call Dlay5 ; Wait 5 msecs before Sending Again
EStrobe
call Dlay160 ; Wait 160 usecs before Sending 2nd Time
EStrobe
call Dlay160 ; Wait 160 usecs before Sending 3rd Time
bcf RS ; send an 8 bit instruction
movlw 0x02 ; Set 4 Bit Mode
call NybbleOut
call Dlay160
movlw 0x028 ; 4 bit, 2 Line, 5x7 font
call SendINS
movlw 0x010 ; display shift off
call SendINS
movlw 0x001 ; Clear the Display RAM
call SendINS
call Dlay5 ; Note, Can take up to 4.1 msecs
movlw 0x006 ; increment cursor
call SendINS
movlw 0x00C ; display on cursor off
call SendINS
return
;----------------------------------------------------------------------;
; Send the character in W out to the LCD ;
;----------------------------------------------------------------------;
SendASCII
addlw '0' ; Send nbr as ASCII character
SendCHAR ; Send the Character to the LCD
movwf Temp ; Save the Temporary Value
swapf Temp, w ; Send the High Nybble
bsf RS ; RS = 1
call NybbleOut
movf Temp, w ; Send the Low Nybble
bsf RS
call NybbleOut
return
;----------------------------------------------------------------------;
; Send an instruction in W out to the LCD ;
;----------------------------------------------------------------------;
SendINS ; Send the Instruction to the LCD
movwf Temp ; Save the Temporary Value
swapf Temp, w ; Send the High Nybble
bcf RS ; RS = 0
call NybbleOut
movf Temp, w ; Send the Low Nybble
bcf RS
call NybbleOut
return
;----------------------------------------------------------------------;
; Send the nibble in W out to the LCD ;
;----------------------------------------------------------------------;
NybbleOut ; Send a Nybble to the LCD
movwf PORTB
EStrobe ; Strobe out the LCD Data
call Dlay160 ; delay for 160 usec
return
;----------------------------------------------------------------------;
; Change binary nbr in bin to BCD ;
;----------------------------------------------------------------------;
binary_to_bcd ; by Scott Dattalo
clrf hundreds
swapf bin, W
addwf bin, W
andlw B'00001111'
skpndc
addlw 0x16
skpndc
addlw 0x06
addlw 0x06
skpdc
addlw -0x06
btfsc bin,4
addlw 0x16 - 1 + 0x6
skpdc
addlw -0x06
btfsc bin,5
addlw 0x30
btfsc bin, 6
addlw 0x60
btfsc bin,7
addlw 0x20
addlw 0x60
rlf hundreds, f
btfss hundreds, 0
addlw -0x60
movwf tens_and_ones
btfsc bin,7
incf hundreds, f
return
;----------------------------------------------------------------------;
; time delay routines ;
;----------------------------------------------------------------------;
Dlay160: movlw D'40' ; delay about 160 usec,(4/loop )
micro4 addlw H'FF' ; subtract 1 from 'W'
nop
nop
nop
nop
nop
nop
btfss STATUS,Z ; skip when you reach zero
goto micro4 ; more loops
return
Dlay5: movlw 5 ; delay for 5 milliseconds
goto $ + 2
msec250: movlw D'250' ; delay for 250 milliseconds
;*** N millisecond delay routine ***
nmsec: movwf cntmsec ; delay for N (in W) millisec
msecloop: movlw D'248' ; 1 usec for load
call micro4 ; this instruction takes 995 usec
nop ; 1 usec
decfsz cntmsec,f ; 1 usec, (2 if skip taken)
goto msecloop ; 2 usec here makes 995+5=1 msec
return
;----------------------------------------------------------------------;
; Display binary value in W in decimal ; ;
;----------------------------------------------------------------------;
DispDec
movwf bin
call binary_to_bcd
movf hundreds, W
call SendASCII
swapf tens_and_ones, W
andlw H'F'
call SendASCII
movf tens_and_ones, W
andlw H'F'
call SendASCII
return
;----------------------------------------------------------------------;
; The Main routine ;
;----------------------------------------------------------------------;
MAIN:
call Init ; initialize ports, set up timer
call initlcd ; initialize the LCD
MAIN1:
CALL INITDS1820 ; init DS1820
MOVLW 0CCH ; skip ROM
MOVWF O_BYTE
CALL OUT_BYTE
MOVLW 44H ; perform temperature conversion
MOVWF O_BYTE
CALL OUT_BYTE
CALL WAIT ; wait for conversion to complete
; wait for all ones from 1820
CALL INITDS1820
MOVLW 0CCH ; skip ROM
MOVWF O_BYTE
CALL OUT_BYTE
MOVLW 0BEH ; read scratchpad
MOVWF O_BYTE
CALL OUT_BYTE
CALL IN_BYTE ; get from DS1820 and save
movwf TEMP_LSB
CALL IN_BYTE
movwf TEMP_MSB
movlw 0x001 ; Clear the Display RAM
call SendINS
call Dlay5 ; Note, Can take up to 4.1 msecs
movlw 0x006 ; increment cursor
call SendINS
movlw 0x00C ; display on cursor off
call SendINS
movlw "A"
call SendCHAR
movlw "m"
call SendCHAR
movlw " "
call SendCHAR
movlw "T"
call SendCHAR
movlw "e"
call SendCHAR
movlw "m"
call SendCHAR
movlw "p"
call SendCHAR
movlw ":"
call SendCHAR
movlw " "
call SendCHAR
rrf TEMP_MSB, f
btfsc STATUS, C
goto dispnega
movlw "+"
call SendCHAR
goto showlsb
dispnega:
movlw "-"
call SendCHAR
goto showlsb
showlsb:
bcf STATUS, C
rrf TEMP_LSB, f
btfsc STATUS, C
goto got5
movf TEMP_LSB,0
CALL DispDec ; display the value
movlw "."
call SendCHAR
movlw "0"
call SendCHAR
CALL msec250
GOTO displayrest
got5:
movf TEMP_LSB,0
CALL DispDec ; display the value
movlw "."
call SendCHAR
movlw "5"
call SendCHAR
displayrest:
movlw "C"
call SendCHAR
CALL msec250
GOTO MAIN1 ; do it again
; The following are standard 1-Wire routines.
INITDS1820:
CALL PIN_HI
CALL PIN_LO
MOVLW 50 ; 500 us delay
CALL DELAY_10USEC
CALL PIN_HI
MOVLW 50 ; 500 usec delay
CALL DELAY_10USEC
RETURN
WAIT:
CALL IN_BYTE
MOVLW 0FFH
SUBWF I_BYTE, W
BTFSS STATUS, Z
GOTO WAIT
RETURN
IN_BYTE: ; returns byte in W
MOVLW 8
MOVWF INDEX
CLRF I_BYTE
IN_BYTE_1:
CALL PIN_LO ; momentary low on DATA_PIN
NOP
NOP
NOP
CALL PIN_HI
NOP
NOP
NOP
NOP
NOP
NOP
NOP
NOP
NOP
NOP
NOP
NOP
NOP
NOP
NOP
MOVF PORTA, W ; 7 usecs later, fetch from DATA_PIN
MOVWF TEMP
BTFSS TEMP, 4
BCF STATUS, C ; its a zero
BTFSC TEMP, 4
BSF STATUS, C ; its a one
RRF I_BYTE, F
MOVLW 6 ; now delay 60 usecs
CALL DELAY_10USEC
DECFSZ INDEX, F
GOTO IN_BYTE_1
MOVFW I_BYTE ; return the result in W
RETURN
OUT_BYTE:
MOVLW 8
MOVWF INDEX
OUT_BYTE_1:
RRF O_BYTE, F
BTFSS STATUS, C
GOTO OUT_0
GOTO OUT_1
OUT_BYTE_2:
DECFSZ INDEX, F
GOTO OUT_BYTE_1
RETURN
OUT_0:
CALL PIN_LO ; bring DATA_PIN low
MOVLW 6 ; for 60 usecs
CALL DELAY_10USEC
CALL PIN_HI
GOTO OUT_BYTE_2
OUT_1:
CALL PIN_LO ; momentary low
CALL PIN_HI
MOVLW 6
CALL DELAY_10USEC
GOTO OUT_BYTE_2
;;;;;;
PIN_HI:
BSF STATUS, RP0
BSF TRISA, DATA_PIN ; high impedance
BCF STATUS, RP0
RETURN
PIN_LO:
BCF PORTA, DATA_PIN
BSF STATUS, RP0
BCF TRISA, DATA_PIN ; low impedance zero
BCF STATUS, RP0
RETURN
DELAY_10USEC: ; provides a delay equal to W * 10 usecs
MOVWF LOOP1
DELAY_10USEC_1:
NOP
NOP
NOP
NOP
NOP
NOP
NOP
NOP
NOP
NOP
NOP
NOP
NOP
NOP
NOP
NOP
NOP
NOP
NOP
NOP
NOP
NOP
DECFSZ LOOP1, F
GOTO DELAY_10USEC_1
RETURN
end
Ruben Jönsson [rubenj@pp.sbbs.se] says:
HiI have built an RS485 master/slave networked temperature measurement system were each RS485 node can connect to up to 32 DS18S20 devices on a 1-wire network.
The system is used for measuring temperatures on grain at different heights in a grain bin. The temp sensors are inside a cable that is hanging from the ceiling in the bin. Each cable is connected to one RS485 node.
The network is connected to a PC which displays a physical layout of the site (could be a picture or a scanned blueprint) with temperature values overlayed on the image at different colors depending on alarm and warning levels.
The board for the RS485 node is equiped with 1 SX18 processor at 4MHz, 1 24LC16 EEPROM for storing the 1-wire device addresses of each sensor connected to this node (the addresses are automatically scanned and detected with a ROM search upon power up), the 485 circuitry (2400bps, half duplex), interface circuitry for the 1-wire, 2 BCD switches to set the address of the node and 2 leds for status indication.
I have also done a version of this board that is a stand alone hand held battery operated unit with an LCD and two buttons. This is limited to cables with max 14 1-wire tempsensors.
I have used the EEPROM in the 1820 sensor to store an index number of the physical location of the sensor on the 1-wire network in the cable. When the device address is found during the ROM search I know at which height level this sensor is located in this cable.
==============================
Ruben Jönsson
AB Liros Elektronik
Box 9124, 200 39 Malmö, Sweden
TEL INT +46 40142078
FAX INT +46 40947388
ruben@pp.sbbs.se
==============================
See:
Questions:
HI,James Newton replies: See: PIC LCD routines+
I'm facing some problems in programming the LCD with the assemply language.
I need to know how to program the LCD to interface it with the PIC 16F877.
Regards,
Sara K.
Hi,+
I am having trouble with my Maxim DS18S20 sensor which I am trying to interface with PIC16F877. To test the sensor, I am trying to transmit the temperature byte by implementing USART. I get some kind of output on the DQ pin, which I see using an oscilloscope. But the output that I get is 8 bits which are all ones, followed by an almost equal interval of the pin driven low and then it is back to its high impedance state. Another question I have is... if I am using a 4 MHz crystal, then one instruction is executed in 1 us or 0.25 us. Any help on this would be appreciated greatly. Thank you very much.
Comments:
See also:
http://www.micro-examples.com/public/microex-navig/doc/083-keypad-library.html hi...i would like to ask some assistance from someone out there who had already experienced connecting DS1820 sensor to PIC16F8777A..i was just confused about the relationship of DS1820 with the analog+
MCP9700A...
| file: /Techref/microchip/ds1820-code.htm, NaNKB (1 imgs) in 0.082s is NaNKBps, updated: 2009/4/22 23:21, local time: 2025/4/21 21:37,
18.190.207.149:LOG IN
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