ReadTemp Header File Redo

[kent_twt4]

Time to redo the internal ReadTemp function. I will be tinkering with the old one to update the Dallas one-wire code for the ds18s20, ds18b20 and PAR (parasitic) devices. If anyone wants to add features, or test the example code, jump right in.

I will edit the header file while going thru the process.

O.K. here is an example using the DS18B20, I haven't tested the negative function in the freezer yet:

'Chip model, Oscillator frequency FOSC 
#chip 18f26k22,8
#config OSC=INTIO67

'Setup 4 bit LCD 
#define LCD_IO 4
#define LCD_DB4 PORTB.4
#define LCD_DB5 PORTB.5
#define LCD_DB6 PORTB.6
#define LCD_DB7 PORTB.7
#define LCD_RS PORTC.5
#define LCD_RW PORTC.6
#define LCD_Enable PORTC.7

'***************************************
'    DS18B20 One Wire Temp
'***************************************
#include <NewReadtemp.h>
#define ds18b20
Dim DummyRead As Word
#define DQ PortA.2
'***************************************

Main:       
DummyRead = OWTemp
cls
    If DummyRead.8 1 Then
        Print "-"
        DummyRead = DummyRead - 128  'Negative two's compliment reading
    End if
        'LCDInt DummyRead
    Print DummyRead
    If DummyRead.0 1 Then Print ".5"
    If DummyRead.0 0 Then Print ".0"
    Print " Deg C "
    locate 1,0
    Print "NewReadTemp.h"
wait 1 s
goto Main

[kent_twt4]

Header file named NewReadTemp:

'=========ROM Commands for 1-Wire DS18S20 DS18B20======================================
#define SearchRom 240       '0xF0 Identify Slave Rom codes
#define ReadRom 51          '0x33 Command for single slave
#define MatchRom 85         '0x55 To identify a specific slave code
#define SkipRom 204         '0xCC Address all devices simultaneously
#define AlarmSearch 236     '0xEC Search Rom to identify any alarm flags
'==========Function Commands for for 1-Wire DS18S20 DS18B20=============================
#define ConvertT 68         '0x44 Single Temp Conversion
#define WriteScratch 78     '0x4E Write Scratchpad
#define ReadScratch 190     '0xBE Read Scratchpad
#define CopyScratch  72     '0x48 Copying Scratchpad TH and TL registers to EEPROM
#define RecallE2 187        '0xB8 Recalling alarm trigger values from EEPROM 

Dim HighLow As Word
Dim OWTemp As Word

function OWTemp
MasterRST
OWout SkipRom
OWout ConvertT
#IfDEF PARasitic
    Set Pullup On
#EndIf
wait 750 ms                 'Need approx. 750 ms for 12 bit conversion
#IfDEF PARasitic
    Set Pullup Off
#EndIf
MasterRST
OWout SkipRom
OWout ReadScratch
Owin
#IfDEF ds18b20              'Assumes factory default 12bit resolution
    HighLow  = HighLow / 16 'Right shift temperature MSB into lower byte
#Endif
OWTemp = HighLow
If HighLow.8 1 Then         'Test for sign bit
    OWTempL = HighLow       'Split word into bytes so byte size
    OWTempH = HighLow_H     ' assembler operations can be used 
    comf  OWTempL           'Invert Low byte bits in the Register
    incf  OWTempL           'Add One to Low byte to turn into 2's compliment 
    comf  OWTempH           'Invert High byte bits
    OWTemp = OWTempL        'Reassemble bytes back into word 
    OWTemp_H = OWTempH
End if
end function

'-----SUBS-----------------------------------------
Sub MasterRST               'Master reset low for minimum 480 us
Dir DQ In
Dir DQ Out
Set DQ Off
wait 50 10us
Dir DQ In                   'HiZ the bus line for reading presence pulse
wait 48 10us                'wait for presence pulse from one-wire device 
end sub

Sub OWout (Command) #NR
Clocks = 0
For Clocks = 1 to 8 
    Dir DQ Out
    Set DQ Off
    wait 3 us               'Need to release bus within 15 us
    If Command.0 On then
        Dir DQ In
    End if
    wait 60 us              '60 us per AN2420
    Dir DQ In               'HiZ the bus if still pulled low
    wait 3 us
    ROTATE Command Right    'The DS18s20 wants data LSB first
Next
end sub

Sub OWin
HighLow = 0
For bits = 1 to 16
    Rotate HighLow Right    'The one wire devices xmit data LSB first
    Dir DQ Out
    Set DQ Off              'Start Read time slot
    wait 6 us  
    Dir DQ In               'Release bus for one wire Reception
    wait 4 us  
    If DQ On  Then Set HighLow.15 1  'Must read bus within 15us slot
    If DQ Off Then Set HighLow.15 0
    wait 50 us
Next
end sub

[Anobium]

Can we retain the existing header file and add the new functionality to the existing file?

We should retain the existing function ReadTemp. You add a new function ReadTemp12 for the newer devices or add some parameters to control the method.

Cheers.

[kent_twt4]

Yes, the existing function would be retained. The NewReadTemp is required till testing is complete; don't want to confuse myself or the compiler :). The new header saves several variables, and deletes an extra sub. More work required.

I thought I would use 9bit as default. We could have other resolutions with optional #defines.

[kent_twt4]

O.K. here is a revised header file with some #defines. Should be backward compatible with the DS18s20.

Will be working up an example on how to read the internal 8 byte of ROM (i.e. family code, 6 byte serial no., and CRC) from the ReadRom command. Getting the serial number allows a multidrop device scenario on a single data line.

2/18/14 Refactored waits in Read Time Slot because of sketchy first reads depending on OSC. Freezer tested for negative numbers.

'=========ROM Commands for 1-Wire DS18S20 DS18B20======================================
#define SearchRom 240       '0xF0 Identify Slave Rom codes
#define ReadRom 51          '0x33 Command for single slave
#define MatchRom 85         '0x55 To identify a specific slave code
#define SkipRom 204         '0xCC Address all devices simultaneously
#define AlarmSearch 236     '0xEC Search Rom to identify any alarm flags
'==========Function Commands for for 1-Wire DS18S20 DS18B20=============================
#define ConvertT 68         '0x44 Single Temp Conversion
#define WriteScratch 78     '0x4E Write Scratchpad
#define ReadScratch 190     '0xBE Read Scratchpad
#define CopyScratch  72     '0x48 Copying Scratchpad TH and TL registers to EEPROM
#define RecallE2 187        '0xB8 Recalling alarm trigger values from EEPROM 

Dim HighLow As Word
Dim OWTemp As  Word

function OWTemp
MasterRST
OWout SkipRom
OWout ConvertT
#IfDEF PAR
    Set ReadTemp_Pullup On
#EndIf
#IFNDEF PAR                 'start master read time slots until ds18x20 returns a "1"
Do Until ConvertDone = True
    dir DQ out
    Set DQ Off
    wait 4 us
    Dir DQ In
    wait 7 us
    If DQ On Then
    ConvertDone = True
    Else
    ConvertDone = False
    End If
    wait 60 us              'minimum 60 us time slots between reads  
Loop
#ENDIF
#IfDEF PAR
    wait 750 ms             'Need approx. 750 ms for full conversion
    Set ReadTemp_Pullup Off
#EndIf
MasterRST
OWout SkipRom
OWout ReadScratch
Owin
If HighLow.15 1 Then        'Test for sign bit
    Call NegNumber
    ReadTemp_Neg = True
Else
    ReadTemp_Neg = False
End If
#IFDEF ds18b20              'Assumes factory default 12bit resolution
    #IFDEF ReadTemp_8Bits
        HighLow  = HighLow / 16 'Right shift temperature MSB into lower byte
    #ENDIF
    #IFDEF ReadTemp_9Bits
        HighLow  = HighLow / 8
    #ENDIF
    #IFDEF ReadTemp_10Bits
        HighLow  = HighLow / 4
    #ENDIF
    #IFDEF ReadTemp_11Bits
        HighLow  = HighLow / 2
    #ENDIF
    '#IFDEF ReadTemp_12Bits (DS18b20 default) leaves HighLow unchanged

#ENDIF
#IFNDEF ds18b20
    #IFNDEF ReadTemp_9Bits
        HighLow  = HighLow / 2  'Right shift temperature MSB into lower byte
    #ENDIF
    'IFDEF ReadTemp_9Bits (DS18s20 default) leaves HighLow unchanged
#ENDIF
OWTemp = HighLow

end function

'-----SUBS-----------------------------------------
sub NegNumber
    ReadTemp_Neg = True 
    #IFDEF PIC 
        comf  HighLow       'Invert Low byte bits in the Register
        incf  HighLow       'Add One to Low byte to turn into 2's compliment 
        comf  HighLow_H     'Invert High byte bits
    #ENDIF
    #IFDEF AVR 
        neg  HighLow        'Invert Low byte bits in the Register
        inc  HighLow        'Add One to Low byte to turn into 2's compliment 
        neg  HighLow_H      'Invert High byte bits
    #ENDIF
end sub

Sub MasterRST               'Master reset low for minimum 480 us
Dir DQ In
Dir DQ Out
Set DQ Off
wait 50 10us
Dir DQ In                   'HiZ the bus line for reading presence pulse
wait 48 10us                'wait for presence pulse from one-wire device 
end sub

Sub OWout (IN Command)
Clocks = 0
For Clocks = 1 to 8 
    Dir DQ Out
    Set DQ Off
    wait 3 us               'Need to release bus within 15 us
    If Command.0 On then
        Dir DQ In
    End if
    wait 60 us              '60 us per AN2420
    Dir DQ In               'HiZ the bus if still pulled low
    wait 3 us
    ROTATE Command Right    'The DS18s20 wants data LSB first
Next
end sub

Sub OWin (OUT HighLow as Word)
HighLow = 0
For bits = 1 to 16
    Rotate HighLow Right    'The one wire devices xmit data LSB first
    Dir DQ Out
    Set DQ Off              'Start Read time slot
    wait 4 us  
    Dir DQ In               'Release bus for one wire Reception
    wait 7 us  
    If DQ On  Then Set HighLow.15 1  'Must read bus within 15us slot
    If DQ Off Then Set HighLow.15 0
    wait 50 us
Next
end sub

[kent_twt4]

HOW TO READ DSx1820 INTERNAL ROM CODE

Here is an example on how to read a bus powered single DS18b20 internal ROM code. Once individual ROM codes are learned, then a multi drop network can be effected on a single Data pin.

'This is an example for reading out a single bus powered DS18b20's ROM code.
'family code (1 byte, 0x28), serial number (6 bytes), CRC (1 byte)
'A typical example: 40 40 5 152 3 0 0 194

'Chip model, Oscillator frequency FOSC
#chip 18f26k22,8
#config OSC=INTIO67

'Setup 4 bit LCD
#define LCD_IO 4
#define LCD_DB4 PORTB.4
#define LCD_DB5 PORTB.5
#define LCD_DB6 PORTB.6
#define LCD_DB7 PORTB.7
#define LCD_RS PORTC.5
#define LCD_RW PORTC.6
#define LCD_Enable PORTC.7

#include <NewReadtemp.h>
'#define ds18b20
'#define ReadTemp_9Bits     'Want to read 1/2 degree resolution
'make use of the ReadTemp_Neg (True) Flag for negative temperatures
'Dim DummyRead As Word
#define DQ PortA.2

Main:
cls
MasterRST                     'start initialization process
OWout ReadRom
OWinRom
wait 2 s
goto Main

Sub OWinRom
For EightBytes = 1 to 8
 For Clocks = 1 to 8
  Rotate RxData Right 'The DS18s20 wants data LSB first
  Dir DQ Out
  Set DQ Off  'Read time slot
  wait 4 us
  Dir DQ In   'Release bus for one wire transmission
  wait 7 us
  If DQ On  Then Set RxData.7 1
  If DQ Off Then Set RxData.7 0
  wait 50 us
 Next
  If EightBytes = 5 Then Locate 1,0
  Print RxData: Print "  "
  wait 1 s
Next
end sub

[Anobium]

Cant wait to test at the weekend!

[Anobium]

@kent_twt4: Questions.

From my research of DS1820, DS18S20 and the DS18B20.

Device	Capability
DS1820	Temp returned as a fixed 9 Bit resolution
DS18S20	Temp returned as a 9 Bit resolution but 12 bit resolution can be calculated
DS18B20	Temp returned as 9 to 12 Bit resolution configured by designer

Will the new header support all three devices?

This is table of the capabilities per device.

See the attachment - gave up formatting the table!

Will we be able perform all the operations above in the new header? (I had to create this table as I could not find this consolidated information on the web....I am sure it exists somewhere!). Did I miss any capability?

[kent_twt4]

The question always is how much functionality to bring to the table in a header, as opposed to showing the methods used to obtain a result? I am open to discussion.

Another question I have is; does the ReadTemp, and the much larger category of Dallas 1-Wire devices deserve a separate header file (say 1-Wire.h or OneWire.h?), as opposed to a System.h? (or wherever ReadTemp is currently stashed).

1. Supposedly the DS18S20 is meant to be a drop in replacement for the DS1820 per Maxim/Dallas DS18S20 DS18B20 comparison pdf. The exception being the increased resolution and the conversion time of the DS18S20 http://pdfserv.maximintegrated.com/en/an/AN4377.pdf I don't foresee any problems with the DS1820 device since the ReadTemp is polling the conversion time.

2. I have not planned to use the DS18S20 in the increased resolution mode. Bloated maths, and not matching the accuracy of +/- 0.5C of the device to it's resolution thing for me.

3. The Table looks good.

4. Setting and reading alarms is easy enough to incorporate.

5. I don't have any ready code for the SearchRom command. My thoughts are if you don't know what devices you have, or their location in the chain, you have got problems? Perhaps I could be persuaded though :).

6. Instead of doing software bit resolution for the DS18B20, we could make those as hardware EEProm R1, R0 bit configuration register settings. This would make for MUCH quicker ConvertT times for bus powered devices. Put a timer on ConvertT and get around 600+ ms 12 bit conversion, while a 9 bit conversion is "supposed" to be just under 100 ms.

[Anobium]

Good point regarding header and method. Can we provide read temp for 9 bit and 12 bit, set / read alarm and read unique serial #/read unique device? The rest can be derived anyway from these. I think you are pretty close to this anyway.
I like the idea of a new OneWire.h as this will have non device specific methods and we should place all the DS18x20 methods in the old DS18S20.h file. So, to use you would need <onewire.h> and <ds18s20.h>

Re your list.

1. Agree re this point.
2. We should do a 12 bit – readtemp12 sounds like a good name for the method. I have some maths I can share.
3. I will update the table to show what is support and what people have to hand crank.
4. Good.
5. I think if you cracked the searchrom we would have something better than a few other compilers – please, please.
6. If it works – then any valid approach is good.
   
   FYI: I just checked the current ds18s20.h it is your code dated Feb 12, 2007, Rev0.

:-)

[kent_twt4]

Put up a Dallas 1-Wire temperature sensor network example in the Contributors section. The link: https://sourceforge.net/p/gcbasic/discussion/629990/thread/0d52cc35/#6609

Not much usable from the header file, so it is self contained so to speak. Also it uses the manual ROM discovery method as shown in previous post.

I really tried to use integer values, but having a heck of time with the syntax. I am not sure if a function can handle Integers?

[kent_twt4]

Ughhh....Finally got the SearchRom code. Had to sneak a peek at the Dallas appnote 187 to get things going in the right direction. I was able to get three in a row on my own and then a total roadblock.

Anyway, how many devices should the header file be able to discover? 16 devices might fit in a smallish 4KByte flash, 256Byte Ram device, OR???

[Anobium]

@kent. I have finally got to the DS18B20 testing.

Do I need the <NewReadtemp.h> file to make the READROM work correctly?

Anobium

[kent_twt4]

Evan,

No need for the NewReadTemp.h include.  Perhaps the OWinRom routine would be of help though.  I'm pretty sure I put up an example in the contributor section.  The OWin bytes need to be printed out or saved to a buffer.  Here's a recap:

cls
MasterRST                     'start initialization process
OWout ReadRom
OWinRom
wait 2 s
goto Main

Sub OWinRom
For EightBytes = 1 to 8
 For Clocks = 1 to 8
  Rotate RxData Right 'The DS18s20 wants data LSB first
  Dir DQ Out
  Set DQ Off  'Read time slot
  wait 4 us
  Dir DQ In   'Release bus for one wire transmission
  wait 7 us
  If DQ On  Then Set RxData.7 1
  If DQ Off Then Set RxData.7 0
  wait 50 us
 Next
  If EightBytes = 5 Then Locate 1,0
  Print RxData: Print "  "
  wait 1 s
Next
end sub

On Monday, August 11, 2014 8:30 AM, Anobium evanvennn@users.sf.net wrote:

@kent. I have finally got to the DS18B20 testing.
Do I need the <NewReadtemp.h> file to make the READROM work correctly?
Anobium

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ReadTemp Header File Redo

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