28022 Parallax Inc, 28022 Datasheet - Page 7

• Manufacturer Part Number: 28022
• Description: KIT DS2760 THERMOCOUPLE
• Manufacturer: Parallax Inc

Specifications of 28022

• Lead Free Status: Contains lead
• Accessory Type: Thermocouple Kit
• For Use With/related Products: BASIC Stamp® Modules
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

' Reads cold junction (device) temperature
' -- each raw bit = 0.125 degrees C
' -- returns tmpCJ in whole degrees C
Read_CJ_Temp:
' Search currently selected TC table for nearest entry
' -- uses modified binary algorithm to find cjComp
' -- high end of search set before calling (tblHi)
' -- successful search sets tempC
TC_Lookup:
Parallax, Inc. • DS2760 Thermocouple Kit (#28022) • 01/2004
sign = tCuV.BIT15
tCuV = tCuV >> 3
IF sign THEN
ENDIF
tCuV = ABS tCuV */ 4000
RETURN
OWOUT OW, %0001, [SkipNet, RdReg, $18]
OWIN
IF (tmpCJ.BIT15) THEN
ELSE
ENDIF
RETURN
tblLo = 0
tempC = 22
READ (tblHi * 2), Word testVal
IF (cjComp > testVal) THEN
ELSE
tCuV = tCuV | $F000
tmpCJ = 0
tmpCJ = tmpCJ.HIGHBYTE
error = 1
DO
eePntr = (tblLo + tblHi) / 2
READ (eePntr * 2), Word testVal
IF (cjComp = testVal) THEN
ELSEIF (cjComp < testVal) THEN
ELSE
ENDIF
OW, %0010, [tmpCJ.BYTE1, tmpCJ.BYTE0]
EXIT
tblHi = eePntr
tblLo = eePntr
' save sign bit
' correct alignment
' pad 2's-compliment bits
' x 15.625 uV
' check sign
' disallow negative
' >> 5 x 0.125 (>> 3)
' low entry of table
' default to room temp
' check max temp
' out of range
' midpoint of search span
' read value from midpoint
' found it!
' search lower half
' search upper half
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