' DS18B20_two_thermo.bas for Atmel AVR with BASCOM - AVR and Dallas
semiconductors DS18B20 temperature sensors - NO extra hardware
' Program
"DUAL DS Thermo"
' Messures and
displays temperature in 1/10 celcius on two DS sensors,
' stores and
displays minimum and maximum readings.
' This program
will NOT work on BASCOM earlier than 1.11.6.2, cause of the CRC-function
' and (maybe ?)
its not possible to declare functions in earlier environment.
' But the 1w-functions
work from 1.11.4 , I think.
' The program code
(BIN) will be ~3Kb so its NOT possible to run in DEMO-environment anyway
' Platform(s) :
Atmel devkit ~1996, used "AVR ISP programmer"-setting
' Dev - uC : Atmel
AT90s8515 (AVR) @ 4 Mhz
' BASCOM-AVR IDE
Version : 1.11.6.2 Compiler: Version 1.11.6.2 (released)
' This is a
TWO-sensor DS18b20 thermometer displayed on 2*16 LCD
' The sensors are
on the same 1-w bus :-) which is the
intresting part
' The bus used is
of 2-wire type, that means : Port-PIN to DQ, +5V to VDD and Gnd.
' See also
HTML-help-file in BASCOM regarding "Using the 1 WIRE protocol"
' Main goal is to
show basics of using two DS-sensors on the same uC-pin.
' The code is
written for easy understanding as goal, not optimized for anything else
' If you use it or
test it, please report to the author. (Not when only browsing )
' mailto:
gote@sys-op.com
' subject :
DS18B20_two_thermo.bas test-report
' message : type
of uC, Mhz, type of sensors used, type of cable and length
' platform (devkit
/ PCB ?), BASCOM-version, compiled code
size, (BIN file size)
' That will be
enough pay-back for non-commercial use.
' Changes in the
code will be allowed, if copy of changed program is sent to author,
' with comments in
English ( or German, Swedish ).
' For commercial
use, contact author.
' (c) 2001 Göte
Haluza, gote@sys-op.com, gote@hotmail.com (Sweden)
' version :1 ,
revision 2, Startdate : 18 apr 2001 Last
update : 27 Apr 2001
$regfile = "8515def.dat"
$crystal = 4000000
Declare Sub Init
Declare Sub ConvAllT ' Convert T on ALL sensors
Declare Function Decigrades(BYVAL sc(9) as byte) as integer
Config 1wire = Portb.6 '0,1,2 NOP 3,4,5,6,7 works
good ON MY Equipment
Config Lcd = 16 * 2
Config Lcdpin = Pin , Db4 = Porta.4 , Db5 = Porta.5 , Db6 = Porta.6 , Db7 = Porta.7 , E = Porta.3 , Rs = Porta.2
'Temp variables
Dim B As Byte
Dim W As Word
'Program variables
'Implicit Err created by compiler
Dim Dg As Integer 'DECIgrades, I call it, cause I have
no space for commas on the display....
Dim Min1 As Integer
Dim Min2 As Integer
Dim Max1 As Integer
Dim Max2 As Integer
Dim Dsid1(8) As Byte 'Dallas ID 64 bits incl CRC
Dim DsId2(8) As Byte
'When used like this : DsId(1) = 1wread(8)
'DsId(1) = family code 'Ds1820 10h, DS18B20 28h, Ds18s20
10h
'DsId(2) '48 Bits Serial, LSB
'DsId(3)
'DsId(4)
'DsId(5)
'DsId(6)
'DsId(7) '48 Bits Serial, MSB
'DsId(8) '8 CRC
Dim Sc(9) as byte 'Scratchpad 0-8 72 bits incl CRC, explanations for DS18b20
'Sc(1) 'Temperature LSB
'Sc(2) 'Temperature MSB
'Sc(3) 'TH/user byte 1 also SRAM
'Sc(4) 'TL/user byte 2 also SRAM
'Sc(5) 'config also SRAM x R1 R0 1 1 1 1 1 - the r1 r0 are config for resolution - write FF to
byte for 12 bit - others dont care
'Sc(6) 'res
'Sc(7) 'res
'Sc(8) 'res
'Sc(9) '8 CRC
'DALLAS DS18B20 ROM and scratchpad
commands''''''''''''''''''''''''''1wwrite....
'&H 33 read rom
- single sensor
'&H 55 match
rom, followed by 64 bits
'&H CC skip rom
'&H EC alarm
search - ongoining alarm >TH <TL
'&H BE read
scratchpad
'&H 44 convert
T
cls
lcd "This is a 2sensor DS18B20 thermometer"
locate 2,1
lcd " by
gote@sys-op.com"
wait 1
for b = 1 to 20
shiftlcd left
waitms 500
next
wait 2
cls
W = 1wirecount()
' Here I assume 2 sensors - no errorcontrol made, but
would be easy to do with the "Err"-variable
' Getting the two sensors IDs.
DsId1(1) = 1wsearchfirst()
Do
DsId2(1) = 1wsearchnext()
Loop Until Err = 1
' If displayed, everything went well.
' First sensor identified and stored in variable
if dsid1(8) = crc8(DsId1(1), 7) then ' Control that the received CRC match the calculated
locate 1,1
lcd "CRC OK Sensor 1 ID"
wait 1
locate 1,1
for B=1 to 8
lcd Hex(DsId1(b))
next
end if
' Second sensor
if dsid2(8) = crc8(DsId2(1), 7) then
locate 2,1
lcd "CRC OK Sensor 2 ID"
wait 1
locate 2,1
for B=1 to 8
lcd Hex(DsId2(b))
next
end if
wait 1
cls
Init
' Main loop
Do
ConvAllT ' "Convert ALL T on the 1w-bus"
Waitus 200 : waitus 200 : waitus 200 : waitus 200 'if you use
2-wire, could be reduced to 200us
1wverify DsId1(1) 'Issues the
"Match ROM "
locate 1,1
if err = 1 then
lcd "Err " 'Err = 1 if
something is wrong
elseif err = 0 then 'lcd " Sensor found"
1wwrite &HBE
Sc(1) = 1wread(9) 'read bytes into array
if sc(9) = crc8(sc(1),8) then
DG = DeciGrades(sc(9))
if min1 > dg then min1 = dg
if max1 < dg then max1 = dg
lcd dg : locate 1,7 : lcd min1 : locate 1,14 : lcd max1
end if
end if
1wverify DsId2(1)
locate 2,1
if err = 1 then
lcd "DsId2 not on bus "
elseif err = 0 then ' lcd " Sensor found "
1wwrite &HBE
Sc(1) = 1wread(9)
if sc(9) = crc8(sc(1),8) then
DG = DeciGrades(sc(9))
if min2 > dg then min2 = dg
if max2 < dg then max2 = dg
lcd dg : locate 2,7 : lcd min2 : locate 2,14 : lcd max2
end if
end if
wait 1
loop
end 'end program
'Sets variables and LCD for further
use'''''''''''''''''''''''''''''''''''''''''
Sub Init
Cls
Lcd " Min Max"
locate 2,1
Lcd " Min Max"
Min1 = 999 ' to get a real value from start
Min2 = 999
end sub
'Makes the Dallas "Convert T" command on the
1w-bus configured in "Config 1wire = Portb. "
'WAIT 200-750 ms after issued, internal conversion time
for the sensor''''''''''
'SKIPS ROM - so it makes the conversion on ALL sensors on
the bus simultaniously
'When leaving this sub, NO sensor is selected, but ALL
sensors has the actual
'temperature in their scratchpad ( within 750 ms )
Sub ConvAllT
1wreset ' reset the bus
1wwrite &HCC ' skip rom
1wwrite &H44 ' Convert T
End sub
'Makes a integer value of the first two bytes in
scratchpad'''''''''''''
'Works on DS18 B 20 , observe "B". The R0 and R1
in Sc(5) tells you how many bits are accurate
function Decigrades(Byval Sc(9) as byte)
Decigrades = 0
Decigrades = Makeint(Sc(1) , Sc(2))
Decigrades = Decigrades * 10
Decigrades = Decigrades / 16
end function
' If you have DS1820 or DS18 S 20 , you can use this algo instead:
' Observe that DsId1(1) contains the info value of which
sensor is used.
'(
Function Decigrades(byval Sc(9) As Byte)
Dim Tmp As Byte , T As Integer , T1 As Integer
Tmp = Sc(1) And
1 ' 0.1C precision
If Tmp = 1 Then
Decr Sc(1)
T = Makeint(sc(1)
, Sc(2))
'Print Hex(t)
'Print T
T = T * 50 'here we calculate the
1/10 precision like
T = T - 25 'DS18S20 data sheet
T1 = Sc(8) -
Sc(7)
T1 = T1 * 100
T1 = T1 / Sc(8)
T = T + T1
Decigrades = T /
10
'As integer, this routine gives T*10, with 1/10 degree
precision
End Function
')
