Page 138 - Making PIC Microcontroller Instruments and Controllers

rra clocKs. MEilollY. lllD socKETs

i,FlQma{btls ljsing the DSl82o (Prosam to read temp€rature bv
microEngineering (ContDued)
Labs)
ENDIF
CoMMAND = CO!4!AND >> 1 ; shift to nex! biL
NEXIT I
RETI'RN
; write a 0 bit to the Ds1802
WRIEE0 !
TJOW DQ
PAUSEIIS 50 ; low for > 60us for 0
DQ-DrR = 1 ; release data pin {set to rnpul
; for hish)
REl\tRN ; wrile a 1 bit Lo lhe DS1820
WRIBEl:
Irolr DQ ; low for < 15us for 1
eNoP ; delay 1us at 4mnz
DQ,DTR = 1 ; release daia pin (set to inpu!
; for hish)
PAusEus 50 ; use uP rest of line sLot
RlruRN ; tead ldperature fron the DS1820
READ1A2O:
F O R r - 1 t O 1 6 ; 1 6 b i t s t o a o r d
TEDTP - IEUP >> 1 ; shift dom bits
GOSUB RE:ADBI9 ; €reb lhe bit to lhe Lop of lenp
NEJKT I
RlrqRN ; tead a bit fron lhe Ds1820
READBIT t
TE!rP.15 = I ; presei read bi! !o 1
r,ow DQ ; slart the tirne sloL
qNoP ; delay 1us at 4mhz
DLDrR = 1 ; release data pin (seL to input
; for hish)
I F D Q = O T H E N
TEMP.15 = 0 ; se! bic to 0
ENIDIF
PAusEus 50 ; vait ouL res! of tine slo!
RTTURN
END

lo
li!&ijiiil*i.ilFf Using the Ds1620 (microEnsinee ng Labs prcsram read
This nicroEngineerincr Labs progran, too, can be found on
lheir tleb site. Use the latest versron
PICBASIC PRO proerran to read DS1520 Lhree-wire tenperaLure

and display tenperature on the LCD