28018 Parallax Inc, 28018 Datasheet - Page 6

• Manufacturer Part Number: 28018
• Description: MODULE SENSOR TEMP+HUMIDITY
• Manufacturer: Parallax Inc
• Series: Sensirion SHT11r

Specifications of 28018

• Output Type: Digital - 2-Wire
• Sensor Type: Humidity and Temperature
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant, Lead free / RoHS Compliant

' measure humidity
'
SHT_Measure_Humidity:
' sends "status"
'
SHT_Write_Status:
Parallax, Inc. • Sensirion SHT11 Sensor Module (#28018) • 07/2003
6
soT.LowByte = ioByte
' Note: Conversion factors are multiplied by 10 to return the
'
tC = soT ** $1999 - 400
tF = soT ** $2E14 - 400
RETURN
GOSUB SHT_Start
ioByte = ShtHumi
GOSUB SHT_Write_Byte
GOSUB SHT_Wait
ackBit = Ack
GOSUB SHT_Read_Byte
soRH.HighByte = ioByte
ackBit = NoAck
GOSUB SHT_Read_Byte
soRH.LowByte = ioByte
' linearize humidity
'
'
' for the BASIC Stamp:
'
'
' Conversion factors are multiplied by 10 to return tenths
'
rhLin = (soRH ** $67AE) - (soRH ** $83 * soRH ** $5B) - 40
' temperature compensated humidity
'
'
' Conversion factors are multiplied by 10 to return tenths
' -- simplified
'
rhTrue = (tC - 250) * (soRH ** $34) + rhLin
RETURN
GOSUB SHT_Start
ioByte = ShtStatW
rhLin = (soRH * 0.0405) - (soRH^2 * 0.0000028) - 4
rhLin = (soRH * 0.0405) - (soRH * 0.002 * soRH * 0.0014) - 4
rhTrue = (tc - 25) * (soRH * 0.00008 + 0.01) + rhLin
temperature values in tenths of degrees
' convert to tenths C
' convert to tenths F
' alert device
' humidity command
' send command
' wait for measurement
' another read follows
' get MSB
' last read
' get LSB
' alert device
' write to status reg cmd