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beatkrik
Joined: 17 May 2006
Posts: 13
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 Posted: Mon Mar 02, 2015 12:30 pm Post subject: HTU21D temperature and humidity sensor 3V3 |
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Tested the HTU21D Sensor, you can order an Arduino breakout board
14bit's resolution temperature reading
12bit's resolution humidity readout
have to check out CRC.
| Code: |
'Name: M32 HTU21D Test04.bas
'Purpose: Validation Test
'Date: 26-02-2015
$regfile = "m32adef.dat" ' specify the used micro
$crystal = 16000000 ' used crystal frequency
$hwstack = 100 ' default use 32 for the hardware stack
$swstack = 100 ' default use 10 for the SW stack
$framesize = 150 ' default use 40 for the frame space
$baud = 19200
'
'------- For Timer 0 routine --------
Dim Cnt As Byte
Dim Timestamp As Dword
Dim Sec_flag As Bit
'--------------HTU21D----------------
dim temp as single
dim hum as single
dim hum_comp as single
'--------- Config I/O Pin's ---------
Config Portd.7 = Output 'Enable pin for Alive LED
Reset Portd.7
Led Alias Portd.7
'
Config Porta.7 = Output 'RS485 enable pin
Rs485_en Alias Porta.7
Reset Rs485_en
'
'------------------------- SUB Routine's ---------------------------------------
declare function HTU21D_temp() as single
declare function HTU21D_hum() as single
declare sub init_htu21d
'------------------- Config Timer0 for 1 second TICK ---------------------------
Const Timer0reload = 250
Config Timer0 = Timer , Prescale = 256
On Ovf0 Timer0_isr_250ms
Load Timer0 , Timer0reload
Enable Timer0
Start Timer0
'------------------- Config and init I2C bus -----------------------------------
Config Sda = Portc.1
Config Scl = Portc.0
Config I2cdelay = 10 '100KHz clock
I2cinit
'-------------------------------------------------------------------------------
'
'--------------------- Open Soft comport for data output -----------------------
Open "comc.3:38400,8,n,1" For Output As #2
Print #2,"#" ; Version(3) ; ",";
Print #2,Version(1)
print #2,"HTU21D Output"
'
'-------------------------------------------------------------------------------
Enable Interrupts
'*******************************************************************************
'------------------------------------- MAIN ------------------------------------
call init_htu21d
Do
If Sec_flag = 1 Then
Reset Sec_flag
Toggle Led
print #2,timestamp;",";
temp=htu21d_temp()
print #2, fusing(temp,"#.##");",";
hum=htu21d_hum()
print #2, fusing(hum,"#.##");",";
hum_comp=25-temp
hum_comp=hum_comp*-.15
hum_comp=hum+hum_comp
print #2,fusing(hum_comp,"#.##")
End If
loop
'
close #2
'
End
'*******************************************************************************
'------------------------------ Sub routine's ----------------------------------
'-------------------------------------------------------------------------------
Timer0_isr_250ms:
Load Timer0 , Timer0reload
Incr Cnt
If Cnt > 249 Then
Cnt = 0
Incr Timestamp 'Increase every Second
Set Sec_flag
End If
Return
'-------------------------------------------------------------------------------
function htu21d_temp() as single
local msb as byte
local lsb as byte
local crc as byte
local temp as single
I2cstart
I2cwbyte &H80
i2cwbyte &HE3 'temp hold
I2cstart
i2cwbyte &H81
I2crbyte msb,ack
I2crbyte lsb , Ack
I2crbyte crc , Nack
I2cstop
temp=msb
shift temp, left ,8
temp=temp+lsb
shift temp,right,2 'trunc LSB status bits
shift temp,left,2
temp=temp/65536
temp=temp*175.72
temp=-46.85+temp
htu21d_temp=temp
end function
'-------------------------------------------------------------------------------
function htu21d_hum() as single
local msb as byte
local lsb as byte
local crc as byte
local hum as single
I2cstart
I2cwbyte &H80
i2cwbyte &HE5 'hum hold
I2cstart
i2cwbyte &H81
I2crbyte msb,ack
I2crbyte lsb , Ack
I2crbyte crc , Nack
I2cstop
hum=msb
shift hum, left ,8
hum=hum+lsb
SHIFT hum,right,2 'Trunc lsb status bits
shift hum,left,2
hum=hum/65536
hum=hum*125
hum=-6+hum
htu21d_hum=hum
end function
'-------------------------------------------------------------------------------
sub init_htu21d
'HTU21D Sensor Start up (set in idle mode)
set portc.1 'SCL
waitms 20
reset portc.1 'SCL
'Soft Reset
I2cstart
I2cwbyte &H80
i2cwbyte &HFE
I2cstop
end sub
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beatkrik
Joined: 17 May 2006
Posts: 13
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| Posted: Mon Mar 02, 2015 12:55 pm Post subject: |
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Dewpoint calculation added
| Code: |
'Name: M32 HTU21D Test05.bas
'Purpose: Validation Test
'Date: 02-03-2015
$regfile = "m32adef.dat" ' specify the used micro
$crystal = 16000000 ' used crystal frequency
$hwstack = 100 ' default use 32 for the hardware stack
$swstack = 100 ' default use 10 for the SW stack
$framesize = 150 ' default use 40 for the frame space
$baud = 19200
'
'------- For Timer 0 routine --------
Dim Cnt As Byte
Dim Timestamp As Dword
Dim Sec_flag As Bit
'--------------HTU21D----------------
dim temp as single
dim hum as single
dim hum_comp as single
dim tdew as single
'---------- Constant's --------------
const a=8.1332
const b=1762.39
const c=235.66
'--------- Config I/O Pin's ---------
Config Portd.7 = Output 'Enable pin for Alive LED
Reset Portd.7
Led Alias Portd.7
'
Config Porta.7 = Output 'RS485 enable pin
Rs485_en Alias Porta.7
Reset Rs485_en
'
'------------------------- SUB Routine's ---------------------------------------
declare function HTU21D_temp() as single
declare function HTU21D_hum() as single
declare function Calc_Dew() as single
declare sub init_htu21d
'------------------- Config Timer0 for 1 second TICK ---------------------------
Const Timer0reload = 250
Config Timer0 = Timer , Prescale = 256
On Ovf0 Timer0_isr_250ms
Load Timer0 , Timer0reload
Enable Timer0
Start Timer0
'------------------- Config and init I2C bus -----------------------------------
Config Sda = Portc.1
Config Scl = Portc.0
Config I2cdelay = 10 '100KHz clock
I2cinit
'-------------------------------------------------------------------------------
'
'--------------------- Open Soft comport for data output -----------------------
Open "comc.3:38400,8,n,1" For Output As #2
Print #2,"#" ; Version(3) ; ",";
Print #2,Version(1)
print #2,"HTU21D Output"
'
'-------------------------------------------------------------------------------
Enable Interrupts
'*******************************************************************************
'------------------------------------- MAIN ------------------------------------
call init_htu21d
Do
If Sec_flag = 1 Then
Reset Sec_flag
Toggle Led
print #2,timestamp;",";
temp=htu21d_temp()
print #2, fusing(temp,"#.##");",";
hum=htu21d_hum()
print #2, fusing(hum,"#.##");",";
hum_comp=25-temp
hum_comp=hum_comp*-.15
hum_comp=hum+hum_comp
print #2,fusing(hum_comp,"#.##");",";
tdew=calc_dew()
print #2,fusing(tdew,"#.##")
End If
loop
'
close #2
'
End
'*******************************************************************************
'------------------------------ Sub routine's ----------------------------------
'-------------------------------------------------------------------------------
Timer0_isr_250ms:
Load Timer0 , Timer0reload
Incr Cnt
If Cnt > 249 Then
Cnt = 0
Incr Timestamp 'Increase every Second
Set Sec_flag
End If
Return
'-------------------------------------------------------------------------------
function htu21d_temp() as single
local msb as byte
local lsb as byte
local crc as byte
local temp as single
I2cstart
I2cwbyte &H80
i2cwbyte &HE3 'temp hold
I2cstart
i2cwbyte &H81
I2crbyte msb,ack
I2crbyte lsb , Ack
I2crbyte crc , Nack
I2cstop
temp=msb
shift temp, left ,8
temp=temp+lsb
shift temp,right,2 'trunc LSB status bits
shift temp,left,2
temp=temp/65536
temp=temp*175.72
temp=-46.85+temp
htu21d_temp=temp
end function
'-------------------------------------------------------------------------------
function htu21d_hum() as single
local msb as byte
local lsb as byte
local crc as byte
local hum as single
I2cstart
I2cwbyte &H80
i2cwbyte &HE5 'hum hold
I2cstart
i2cwbyte &H81
I2crbyte msb,ack
I2crbyte lsb , Ack
I2crbyte crc , Nack
I2cstop
hum=msb
shift hum, left ,8
hum=hum+lsb
SHIFT hum,right,2 'Trunc lsb status bits
shift hum,left,2
hum=hum/65536
hum=hum*125
hum=-6+hum
htu21d_hum=hum
end function
'-------------------------------------------------------------------------------
sub init_htu21d
'HTU21D Sensor Start up (set in idle mode)
set portc.1 'SCL
waitms 20
reset portc.1 'SCL
'Soft Reset
I2cstart
I2cwbyte &H80
i2cwbyte &HFE
I2cstop
end sub
'-------------------------------------------------------------------------------
function Calc_Dew() as single
local PPtamb as single
local Tdew as single
PPtamb=temp+c
pptamb=b/pptamb
pptamb=a-pptamb
pptamb=10^pptamb
tdew=pptamb/100
tdew=tdew*hum
tdew=log10(tdew)
tdew=tdew-a
tdew=b/tdew
tdew=tdew+c
tdew=tdew*-1
calc_dew=tdew
end function
'-------------------------------------------------------------------------------
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albertsm
Joined: 09 Apr 2004
Posts: 6197
Location: Holland
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| Posted: Tue Mar 03, 2015 9:31 pm Post subject: |
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Hello beatkrik,
Thanks for sharing your code. Seems like an great sensor. Is this one better than the SH sensor ?
_________________
Mark |
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beatkrik
Joined: 17 May 2006
Posts: 13
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| Posted: Fri Mar 13, 2015 12:52 pm Post subject: |
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Hi Mark,
If you compare the datasheets, The resolution and accuracy between the HTU21 and the SHT21 are equal.
The HTU21 is a bit faster though.
If i have time, i will make some measurements with both sensors. |
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O-Family
Joined: 23 May 2010
Posts: 338
Location: Japan
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| Posted: Fri Mar 13, 2015 2:36 pm Post subject: |
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Hi beatkrik
I also just made a SHT21 of program.
Because I was calculating the CRC, please refer to.
| Code: |
'
' **********************************************
' * SHT21 Temperature & Humidity sensor test *
' * O-Family 2015. 3.13 *
' **********************************************
'
$regfile = "m88pdef.dat"
$crystal = 16000000
'
$hwstack = 64
$swstack = 10
$framesize = 24
Dim I2cbuff(20) As Byte
Dim Sht21comsel As Byte
Dim Temperature As Integer
Dim Humidity As Integer
'
Dim Tempw1 As Word
Dim Templ1 As Long
Dim Tempstr As String * 20
' * LCD initialization *
Config Lcdmode = Port
Config Lcdbus = 4
Config Lcdpin = Pin , Db4 = Portb.3 , Db5 = Portb.2
Config Lcdpin = Pin , Db6 = Portb.1 , Db7 = Portb.0
Config Lcdpin = Pin , E = Portb.4 , Rs = Portb.5
Config Lcd = 16 * 2
'
Deflcdchar 0 , &H08 , &H14 , &H08 , &H06 , &H09 , &H08 , &H09 , &H06
Cursor Off
Cls
' * I2C initialization *
Config Scl = Portd.3
Config Sda = Portd.2
I2cinit
Main:
'
' * Send the measure command to SHT21 *
'
If Sht21comsel = 0 Then 'Temperature measurement?
I2cbuff(5) = &B1111_0011 'Send the Temperature measurement trigger(no-hold) command.
Sht21comsel = 1
Else
I2cbuff(5) = &B1111_0101 'Send the Humidity measurement trigger(no-hold) command.
Sht21comsel = 0
End If
'
I2cstart
I2cwbyte &H80
If Err <> 0 Then Goto Sht21error1 '[ACK] has not come back?
I2cwbyte I2cbuff(5)
Waitus 20 'no-hold waiting time.(20uS)
I2cstop
Waitms 100 'Waiting for measuring time.
'
' * Receive the measurement data from SHT21 *
'
I2cstart
I2cwbyte &H81
If Err <> 0 Then Goto Sht21error2 'Measurement is not finished?
I2crbyte I2cbuff(1) , Ack 'Read the MSB data.
I2crbyte I2cbuff(2) , Ack 'Read the LSB data.
I2crbyte I2cbuff(3) , Nack 'Read the checksum.
I2cstop
'
Gosub Sht21crc 'Calculate the CRC8 for SHT21.
If I2cbuff(3) <> I2cbuff(4) Then Goto Sht21error3 'CRC Error?
'
' * Display the measurement data to LCD *
'
If I2cbuff(2).1 = 0 Then 'Temperature data?
Locate 1 , 1 'Received data HEX display.
Lcd Hex(i2cbuff(1)) ; Hex(i2cbuff(2)) ; Hex(i2cbuff(3)) ; " ";
'
I2cbuff(2) = I2cbuff(2) And &B1111_1100 'Mask the status bit.
Tempw1 = Makeint(i2cbuff(2) , I2cbuff(1)) 'Convert the 2-byte to one word.
Templ1 = 17572 * Tempw1 'Calculation of temperature conversion.
Temperature = Highw(templ1) '1/2^16
Temperature = -4685 + Temperature
Tempstr = Str(temperature)
If Temperature < 0 Then 'Negative value?
Lcd Format(tempstr , " 0.00") ; " " ; Chr(0)
Else
Lcd Format(tempstr , " 0.00") ; " " ; Chr(0)
End If
Else 'Case of humidity data.
Locate 2 , 1 'Received data HEX display.
Lcd Hex(i2cbuff(1)) ; Hex(i2cbuff(2)) ; Hex(i2cbuff(3)) ; " ";
'
I2cbuff(2) = I2cbuff(2) And &B1111_0000 'Mask the status bit.
Tempw1 = Makeint(i2cbuff(2) , I2cbuff(1)) 'Convert the 2-byte to one word.
Templ1 = 12500 * Tempw1 'Calculation of humidity conversion.
Humidity = Highw(templ1) '1/2^16
Humidity = -600 + Humidity
Tempstr = Str(humidity)
Lcd Format(tempstr , " 0.00") ; " %"
End If
'
Main1:
Waitms 900 'Waiting time of 1 second cycle.
Goto Main
'
' * SHT21 Error (ACK is not returned) *
'
Sht21error1:
Locate 2 , 1
Lcd "#SHT21 ACK Error"
Goto Main1
'
' * SHT21 Error (Has not been completed measurement) *
'
Sht21error2:
I2cstop
Locate 2 , 1
Lcd "#SHT21 NACK Ret."
Goto Main1
'
' * SHT21 Error (CRC Error) *
'
Sht21error3:
Locate 2 , 1
Lcd "#SHT21 CRC Error"
'
Locate 1 , 1
Lcd Hex(i2cbuff(1)) ; Hex(i2cbuff(2)) ; Hex(i2cbuff(3)) ; ":" ; Hex(i2cbuff(4)) ; Spc(7)
Goto Main1
'
' * Calculate the CRC8 for SHT21 *
'
Sht21crc:
Loadadr I2cbuff(1) , Z
$asm
LDI R16,$02 'Number of bytes to calculate.
CLR R24 'CRC value.
LDI R22,$31 'POLYNOMIAL = 0x131 P(x)=x^8+x^5+x^4+1 = 1_0011_0001
Sht21crc1:
LD R25,Z+ 'To read the calculated byte.
EOR R24,R25 'CRC = CRC EXOR I2cbuff(x)
LDI R17,$08
Sht21crc2:
LSL R24 'CRC to the left I 1bit shift.
BRcc Sht21crc3 'bit7 of shift before the CRC [1]?
EOR R24,R22 'CRC = CRC EXOR &H31
Sht21crc3:
DEC R17
BRNE Sht21crc2 '8-bit or end?
DEC R16
BRNE Sht21crc1 'Number of bytes to calculate is over?
ADIW R30,1 'Stores the calculated CRC value for the next received byte CRC.
ST Z,R24
$end Asm
Return
'
'
End
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beatkrik
Joined: 17 May 2006
Posts: 13
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| Posted: Mon Mar 16, 2015 12:22 pm Post subject: |
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Thank's O-Family
I wil try to implement your CRC code in my program. Great work ! |
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