DS1820 with 16f688

[Darrel Taylor]

what starting address did you use in your test code?

I tried lots of different address (including 91).
As long as the data statements came before the include (yours does), and the areas didn't overlap, everything was fine.

Of course, I'm using a 16F877.
I don't see any reason why the 688 should be different.

But anyhow, as long as what you have works, why bother looking any further.
<br>

[jessey]

Hi Darrel,

Yes that is strange that it works on the 877 but not on the 688. One of the things that I really like about your EEvars is that you can declare a default value for a variable that is initiated on the first power-up. It's nice to know what the value of a variable is at first power-up especially if it's used to execute a subroutine but I guess I could do some sort of a work a round for that in the code.

Is there a way to declare a default value using EEPROMData?

Thanks
jessey

[Darrel Taylor]

Is there a way to declare a default value using EEPROMData?

Not directly.

But if your data can NEVER include the value 255 ($FF), then yes.

On power up, read the value from EEPROM.
If it's 255, write the "default" value.
Then if you ever need to restore the default value, set the location to $FF and reset.

Unfortunately, some bootloaders have chosen to "erase" EEPROM values to 0 instead of the $FF done by hardware. This can be problematic.
As long as you know which way your programmer works, it's a definite possibility.

ADDED: You can also handle it the same way EE_vars does and create a location that indicates which EEPROM locations have been restored. If the value of that location is less than or equal to (<=) the address being tested, or $FF, restore the default value and only increment the counter AFTER a successful and verified WRITE.
This way 0, $FF and anything less than the address being tested indicates the location needs to be restored.

[jessey]

Unfortunately, some bootloaders have chosen to "erase" EEPROM values to 0 instead of the $FF done by hardware. This can be problematic. As long as you know which way your programmer works, it's a definite possibility.

Hi Darrel,

Thanks for your most welcomed input as it got me thinking on the right path (I'm hoping). I haven't checked yet if my pickit 2 programmer erases the EEPROM values to 0 or 255 when programming but with the code below it wouldn't really matter. I haven't tried this work a round yet but I can't think of any reasons why it wouldn't work.

Thanks Again
jessey

'(2) PIC Config Fuse Definitions for 16f688 
@ __config _INTRC_OSC_NOCLKOUT & _WDT_ON & _MCLRE_OFF & _CP_OFF & _BOD_ON 
@ ERRORLEVEL -306

' Data for house and unit codes
housetbl data $60,$70,$40,$50,$80,$90,$A0,$B0,$E0,$F0,$C0,$D0
      data $00,$10,$20,$30
unittbl data 0,$10,$8,$18,$40,$50,$48,$58

 EEPROMData94 var BYTE
 Set_Point VAR EEPROMData94
 READ 94, EEPROMData94 

 IF Set_Point = 255 THEN
    Set_point = 150  ' Set a default value 
    EEPROMData94 = Set_Point 
    Write 94, EEPROMData94
 ENDIF

IF Set_Point = 0 THEN
    Set_point = 150  ' Set a default value 
    EEPROMData94 = Set_Point 
    Write 94, EEPROMData94
 ENDIF

GOTO Mainloop

My set point doesn't ever need to be set to 0 or 255 in my program and this routine would prevent the user from setting either of the two there.

Adjust_The_Set_Point: 
  Loop1:
      IF Push_Button1 = Is_Pressed THEN
       IF Set_Point < 255 THEN Set_Point = Set_Point + 1 : Save_Var = Yes 
       IF Set_Point > 254 THEN Set_Point = 254 ' 255 is not allowed 
      ENDIF  

      IF Push_Button2 = Is_Pressed THEN
       Set_Point = Set_Point - 1 : Save_Var = Yes 
       IF Set_Point < 2 THEN Set_Point = 1 ' 0 is not allowed 
      ENDIF

      IF Push_Button1 = Is_Not_Pressed THEN  
       IF Push_Button2 = Is_Not_Pressed THEN
        RETURN 
       ENDIF 
      ENDIF 

   Pause 100  
  
  GOSUB Update_The_Lcd ' just in case a button is held down 

  IF a = 0 THEN Loop1 ' a always equals zero, use instead of GOTO... 
     
RETURN

[Darrel Taylor]

Hey jessey,

I guess it's just a matter of semantics, but you may find this interesting.

<font color="#000000"><b>SetPoint   </b><font color="#008000"><b>VAR BYTE </b></font>: <b>SetPoint_DEFAULT  </b><font color="#008000"><b>CON </b></font><font color="#800000"><b>150
</b></font><b>Threshold  </b><font color="#008000"><b>VAR BYTE </b></font>: <b>Threshold_DEFAULT </b><font color="#008000"><b>CON </b></font><font color="#800000"><b>5

</b></font><font color="#008000"><b>DATA </b></font>@<font color="#800000"><b>94                            </b></font><font color="#0000FF"><b><i>; Start this block of data at EE addr 94
</i></b></font><b>EE_SetPoint  </b><font color="#008000"><b>DATA </b></font><b>SetPoint_DEFAULT
EE_Threshold </b><font color="#008000"><b>DATA </b></font><b>Threshold_DEFAULT

</b><font color="#008000"><b>READ </b></font><b>EE_SetPoint</b>, <b>SetPoint               </b><font color="#0000FF"><b><i>; read EE values on powerup
</i></b></font><font color="#008000"><b>READ </b></font><b>EE_Threshold</b>, <b>Threshold
</b><font color="#008000"><b>GOTO </b></font><b>Main

</b><font color="#0000FF"><b><i>;----[Save/Restore EEPROM values]------------------------------------------
</i></b></font><b>Save_SetPoint</b>:                           <font color="#0000FF"><b><i>; write current SetPoint to EEPROM
    </i></b></font><font color="#008000"><b>WRITE </b></font><b>EE_SetPoint</b>, <b>SetPoint          
    </b><font color="#008000"><b>RETURN
</b></font><b>Default_SetPoint</b>:                        <font color="#0000FF"><b><i>; restore default SetPoint value
    </i></b></font><font color="#008000"><b>WRITE </b></font><b>EE_SetPoint</b>, <b>SetPoint_DEFAULT          
    </b><font color="#008000"><b>READ  </b></font><b>EE_SetPoint</b>, <b>SetPoint
    </b><font color="#008000"><b>RETURN
</b></font><font color="#0000FF"><b><i>;-----------------
</i></b></font><b>Save_Threshold</b>:                          <font color="#0000FF"><b><i>; write current Threshold to EEPROM
    </i></b></font><font color="#008000"><b>WRITE </b></font><b>EE_Threshold</b>, <b>Threshold
    </b><font color="#008000"><b>RETURN
</b></font><b>Default_Threshold</b>:                       <font color="#0000FF"><b><i>; restore default Threshold value
    </i></b></font><font color="#008000"><b>WRITE </b></font><b>EE_Threshold</b>, <b>Threshold_DEFAULT
    </b><font color="#008000"><b>READ  </b></font><b>EE_Threshold</b>, <b>Threshold
    </b><font color="#008000"><b>RETURN
</b></font><font color="#0000FF"><b><i>;-----------------
</i></b></font><b>Save_ALL</b>:                                <font color="#0000FF"><b><i>; save ALL values to EEPROM
    </i></b></font><font color="#008000"><b>GOSUB </b></font><b>Save_SetPoint
    </b><font color="#008000"><b>GOSUB </b></font><b>Save_Threshold
    </b><font color="#008000"><b>RETURN
</b></font><b>Default_ALL</b>:                             <font color="#0000FF"><b><i>; restore ALL default values
    </i></b></font><font color="#008000"><b>GOSUB </b></font><b>Default_SetPoint
    </b><font color="#008000"><b>GOSUB </b></font><b>Default_Threshold
    </b><font color="#008000"><b>RETURN
    
</b></font><b>Main</b>: