DS18B20 ID saving To and Reading From EEPROM

[snuff28]

I need a push in the right direction, the answer is probably very simple.

What I want to do is read the DS18B20 ID, save it to the EEPROM, read it back from the EEPROM into a variable to use in the program.

I will have up to 5 DS18B20's that I want to save the address to the eeprom incase one fails I can change on the fly with out reprogramming.

I know I'm going about this all wrong, BUT...

the typical read DS18B20 ID:

Start_Convert:
owout dq, 1, [$33] ' issue read rom command
ID_Loop:
owin dq, 0, [str id\8] ' Read 64-bit device data into the 8-byte array "ID"

From there I save it to the EEPROM:

        write 106, ID[0]
        write 107, ID[1]
        write 108, ID[2]
        write 109, ID[3]
        write 110, ID[4]
        write 111, ID[5]
        write 112, ID[6]
        write 113, ID[7]

Then I can read it from the EEPROM at program start

        READ 98, Tempsensor1[0]
        READ 99, Tempsensor1[1]
        READ 100, Tempsensor1[2]
        READ 101, Tempsensor1[3]
        READ 102, Tempsensor1[4]
        READ 103, Tempsensor1[5]
        READ 104, Tempsensor1[6]
        READ 105, Tempsensor1[7]
        READ 106, Tempsensor2[0]
        READ 107, Tempsensor2[1]
        READ 108, Tempsensor2[2]
        READ 109, Tempsensor2[3]
        READ 110, Tempsensor2[4]
        READ 111, Tempsensor2[5]
        READ 112, Tempsensor2[6]
        READ 113, Tempsensor2[7]
        READ 114, Tempsensor3[0]
        READ 115, Tempsensor3[1]
        READ 116, Tempsensor3[2]
        READ 117, Tempsensor3[3]
        READ 118, Tempsensor3[4]
        READ 119, Tempsensor3[5]
        READ 120, Tempsensor3[6]
        READ 121, Tempsensor3[7]
and so on...

And then I get totaly confused as to how I can select the right sensor and insert the corresponding ID

Right now I am trying with a select case lookup, but clearly thats not working...

 Begin:
    sensor= TEMPSENSOR      'I am reading 5 DS18b20 sensors...

    FOR hexbyte=0 TO 7  'each sensor address is 8 bytes
        GOSUB GetID     'go look up each sensors address
        ID[hexbyte]=col 'load the ID array with the retrieved address byte
    NEXT hexbyte        'go get the rest of the address bytes
    OWOUT DQ, 1, [$55,STR ID\8,$44] 'instructs sensors to match[$55] this[ID] rom code and
                                    'initiates[$44] temperature conversion on matching sensor
    CkAgn:
    OWIN DQ, 4, [Busy]      ' Check for still busy converting
    IF Busy = 0 THEN CkAgn  ' Still busy?, then loop
    OWOUT DQ,1,[$55,STR ID\8,$BE]   'instructs sensors to match[$55] this[ID] and start sending back scratchpad[$BE]
    OWIN DQ, 2, [Raw.LOWBYTE,Raw.HIGHBYTE]' Read two temperature bytes, then end communications
    Dummy = 1125 * Raw
    TempF = DIV32 100
    TempF = TempF + 3200

    GetID:
    SELECT CASE sensor
CASE 1 :LOOKUP hexbyte,[HEX Tempsensor1[0],HEX Tempsensor1[1],HEX Tempsensor1[2],HEX Tempsensor1[3],HEX Tempsensor1[4],_HEX Tempsensor1[5],HEX Tempsensor1 [6],HEX Tempsensor1[7]], col      
CASE 2 :LOOKUP hexbyte,[Tempsensor2[0],[Tempsensor2[1],[Tempsensor2[2],[Tempsensor2[3],_
    [Tempsensor2[4],[Tempsensor2[5],[Tempsensor2 [6],[Tempsensor2[7]], col  
CASE 3 :LOOKUP hexbyte,[Tempsensor3[0],Tempsensor3[1],Tempsensor3[2],Tempsensor3[3],_
    Tempsensor3[4],Tempsensor3[5],Tempsensor3[6],Tempsensor3[7],], col

;*** Temp Sensor 1**********************************************************
    ReadTemp1:
    TEMPSENSOR = 1
    GOSUB Begin
        RETURN
 ;*** Temp Sensor 2  *********************************************************
    ReadTemp2:
    TEMPSENSOR = 2
    GOSUB Begin
        RETURN
 ;*** Temp Sensor3 *********************************************************
    ReadTemp3:
    TEMPSENSOR = 3
    GOSUB Begin
       RETURN
and so on..

I think the array thing is confusing me for some reason.

[Heckler]

take a look here...


http://www.picbasic.co.uk/forum/cont...r-nine-of-them

[snuff28]

Thanks Dwight, I originally used your code and it worked great! but now I want it all done in program. I want to read the device ID, Save it to EEPROM (incase of power failure or what not), and at program start read all the device ID arrays (pre-load it) for use in the program.
That way if I need to change one I wont have to load the read device ID program, get the ID, write it down, go into main program change the string, complie and program. It will be kind of like a hot swap with a selection in the menu to install a new sensor.

[Heckler]

snuff28,

Sorry for my short reply... I tossed it out while at work.

'=============================================================
'           Read Temp Sensor and convert to deg F
'=============================================================
GetTemp:
    OWOUT  Comm_Pin, 1, [$CC, $4E, 0, 0, DS18B20_9bit]  'set resolution of sensor
Start_Convert:
    OWOUT  Comm_Pin, 1, [$CC, $44]' Skip ROM search & do temp conversion

Wait_Up:
    OWIN   Comm_Pin, 4, [Busy]    ' Read busy-bit
    IF     Busy = 0 THEN Wait_Up  ' Still busy..?, Wait_Up..!
    OWOUT  Comm_Pin, 1, [$CC, $BE]' Skip ROM search & read scratchpad memory
    OWIN   Comm_Pin, 2, [Raw.byte0, Raw.byte1]' Read two bytes / end comms

    '--------------  Convert_Temp: -----------------------
    Sign="+"
    IF Cold_Bit = 1 THEN    'it's below zero Celsius
      C=(ABS Raw>>4)*-10      'so shift the ABS value right and mult X -10
      ELSE
      C=(Raw>>4)*10           'else shift value right and mult X 10
    ENDIF

@ CtoF _C, _F             ; Convert Celsius to Fahrenheit
        'converted value will be X 10, ie. 756=75.6 deg F
        'so devide by 10 to get whole degrees

    IF f.15=1 THEN Sign="-" 'if converted value is below zero F then sign is "-"
    TempF = (ABS f)/10      'take tha ABS value and /10
    IF f//10 >4 THEN TempF=TempF+1 'check remainder, if >4 then round up
return      'with TempF containing current temperature

here is a snippet of code that I use in a little project. It's been a while since I wrote it (mostly borrowed from Bruce at Rentron and some help I think from Darrell) and I havent studied it lately either.

But it is agnostic of the device (DS18b20) serial number.
It works with any sensor I install.
I'm guessing that I am able to do that because I am only reading one sensor.

I suspect that if you are trying to read multiple sensors then you have to use the device serial number to address the specific sensor.

Unless you attach only one sensor to a given PIC pin. Then I think you could ignore the device ID.

[Charlie]

If you simply want to be able to swap devices in case of failure (talk to one device at a time only) then don't bother with the serial number at all. You can distinguish the temperature sensor from other types of one wire devices by the family code (if you are building a weather station or something). If you need to talk to a few devices, separate one wire busses on different pins will work for a small number of devices.

[Ioannis]

Maxim has an application note for searching serial numbers of unknown devices. Please see the attached pdf file. It includes the algo and C code (sorry no PBP code yet).

Hope this helps,
Ioannis