GCBASIC / Discussion / GCBASIC Graphical Problems: Problems storing a Long variable in Eeprom

Hello.
I'm attempting to store a "Long" variable value in Eeprom. I only need values upto about 15,000,000 so I'm splitting my "Long" variable across three byte Eeprom locations. My problem is that while checking to see if my maths is correct, my Long variable resets back to zero upon reaching 65536. I have triple checked that I've declared my variables as Long not Word, I have re-written the program a few times to try to eliminate any silly typos, but I just can't see where I'm going wrong.

I'm stumped.

Assuming this is due to a problem with my logic, can anyone suggest how I can store and recall a value of 15,000,000 or thereabouts in Eeprom for displaying on an LCD display?

#Option Explicit

#Chip 16F1829, 32

'LCD connection settings
#Define LCD_IO 4
#Define LCD_SPEED FAST

#Define LCD_NO_RW

#Define LCD_RS              PortA.0
#Define LCD_Enable      PortA.1

#Define LCD_DB4       PortA.2
#Define LCD_DB5       PortC.0
#Define LCD_DB6       PortC.1
#Define LCD_DB7       PortC.2

'Eeprom location
#Define E_Save        10 'Start of Long(ish) Eeprom locations
                         'Occupies 3 bytes for Hi,Mid and Low

Dim     Long_Saved    As Long
Dim     Long_Returned As Long
Dim     S_Hi          As Long
Dim     S_Mi          As Long
Dim     S_Lo          As Long
Dim     Temp          As Byte

Let Long_Saved = GetLEeprom(E_Save)

Do

    Locate 0, 0
    Print "                "
    Locate 1, 0
    Print "                "
    Let Long_Saved = Long_Saved + 135
    PutLEeprom(E_Save, Long_Saved)
    Wait 5 mS
    Locate 0, 0
    Print Long_Saved
    Print " "

    Long_Returned = GetLEeprom(E_Save)
    Locate 1, 0
    Print Long_Returned
    Print " "
    Wait 100 mS
Loop

Sub PutLEeprom (HiAddr As Byte, Save_Long As Long) 'Places a Long(ish) into three bytes of
                                                'Eeprom, HiAddr is the first Byte
                                                'location in Eeprom, the lower Bytes
                                                'are placed into the adjacent bytes
    Let S_Hi      = Save_Long / 65536
    Let Save_Long = Save_Long - (S_Hi * 65536)

    Let S_Mi = Save_Long / 256
    Let S_Lo = Save_Long - (S_Mi * 256)

    EpRead HiAddr,Temp
    If Temp <> S_Hi Then
        EpWrite HiAddr,  S_Hi      'The high byte
    End If

    EpRead HiAddr+1,Temp
    If Temp <> S_Mi Then
        EpWrite HiAddr+1,S_Mi      'The Mid  byte
    End If

    EpRead HiAddr+2,Temp
    If Temp <> S_Lo Then
        EpWrite HiAddr+2,S_Lo      'The Low  byte
    End If

    Locate 0, 7
    Print S_Hi
    Print "  "

    Locate 0, 10
    Print S_Mi
    Print "  "

    Locate 0, 13
    Print S_Lo
    Print "  "

End Sub

Function GetLEeprom (HiAddr As Byte) As Long 'Takes the address of the High Byte and returns
                                             'a Long(ish) made from the HiAddr and the adjacent
                                             'bytes in Eeprom
    EpRead HiAddr,  S_Hi
    EpRead HiAddr+1,S_Mi
    EpRead HiAddr+2,S_Lo

    Locate 1, 7
    Print S_Hi
    Print "  "

    Locate 1, 10
    Print S_Mi
    Print "  "

    Locate 1, 13
    Print S_Lo
    Print "  "

    Let S_Hi = S_Hi * 65536              'Build the High byte
    Let S_Mi = S_Mi *   256              'Build the Mid  byte

    Let GetLEeprom = S_Hi + S_Mi + S_Lo

End Function

Last edit: mkstevo 2017-09-15

Further experimentation has shown that the problem appears to lie with the SubRoutine declaration (and possibly the Function declaration too) where the "As Long" may be incorrectly interpreted.

This works as I'd expected:

#Option Explicit

#Chip 16F1829, 32

'LCD connection settings
#Define LCD_IO 4
#Define LCD_SPEED FAST

#Define LCD_NO_RW

#Define LCD_RS              PortA.0
#Define LCD_Enable      PortA.1

#Define LCD_DB4       PortA.2
#Define LCD_DB5       PortC.0
#Define LCD_DB6       PortC.1
#Define LCD_DB7       PortC.2

'Eeprom location
#Define E_Save        10 'Start of Long(ish) Eeprom locations
                         'Occupies 3 bytes for Hi,Mid and Low

Dim     Long_Saved    As Long
Dim     Long_Returned As Long
Dim     Save_Long     As Long
Dim     Ret_Long      As Long

Dim     S_Hi          As Long
Dim     S_Mi          As Long
Dim     S_Lo          As Long
Dim     Temp          As Byte

GetLEeprom(E_Save)
Let Long_Saved = Ret_Long
If Long_Saved > 16777000 Then
   Let Long_Saved = 0
End If

Do

    Locate 0, 0
    Print "                "
    Locate 1, 0
    Print "                "
    Let Long_Saved = Long_Saved + 135

    Let Save_Long = Long_Saved
    PutLEeprom(E_Save)
    Wait 5 mS
    Locate 0, 0
    Print Long_Saved
    Print " "

    GetLEeprom(E_Save)
    Let Long_Returned = Ret_Long
    Locate 1, 0
    Print Long_Returned
    Print " "
    Wait 100 mS
Loop

Sub PutLEeprom (HiAddr As Byte) 'Places a Long(ish) into three bytes of
                                                'Eeprom, HiAddr is the first Byte
                                                'location in Eeprom, the lower Bytes
                                                'are placed into the adjacent bytes

    Let S_Hi      = Save_Long / 65536
    Let Save_Long = Save_Long - (S_Hi * 65536)

    Let S_Mi = Save_Long / 256
    Let S_Lo = Save_Long - (S_Mi * 256)

    EpRead HiAddr,Temp
    If Temp <> S_Hi Then
        EpWrite HiAddr,  S_Hi      'The high byte
    End If

    EpRead HiAddr+1,Temp
    If Temp <> S_Mi Then
        EpWrite HiAddr+1,S_Mi      'The Mid  byte
    End If

    EpRead HiAddr+2,Temp
    If Temp <> S_Lo Then
        EpWrite HiAddr+2,S_Lo      'The Low  byte
    End If

    Locate 0, 7
    Print S_Hi
    Print "  "

    Locate 0, 10
    Print S_Mi
    Print "  "

    Locate 0, 13
    Print S_Lo
    Print "  "

End Sub

Sub GetLEeprom (HiAddr As Byte) 'Takes the address of the High Byte and returns
                                             'a Long(ish) made from the HiAddr and the adjacent
                                             'bytes in Eeprom
    EpRead HiAddr,  S_Hi
    EpRead HiAddr+1,S_Mi
    EpRead HiAddr+2,S_Lo

    Locate 1, 7
    Print S_Hi
    Print "  "

    Locate 1, 10
    Print S_Mi
    Print "  "

    Locate 1, 13
    Print S_Lo
    Print "  "

    Let S_Hi = S_Hi * 65536              'Build the High byte
    Let S_Mi = S_Mi *   256              'Build the Mid  byte

    'Let GetLEeprom = S_Hi + S_Mi + S_Lo
    Let Ret_Long = S_Hi + S_Mi + S_Lo

End Sub

Anobium - 2017-09-16

@Steve. I think you should review https://sourceforge.net/p/gcbasic/discussion/579126/thread/16ce811d/#ef41

I am thinking you should be addressing as follows:

Dim workvariable as long 'where this is also true lowb = workvariable highb = workvariable_H upperb = workvariable_U lastb = workvariable_E

Then, you can remove some complexity by simply address the bytes with the the long variable.
If you would like to refer to this comment somewhere else in this project, copy and paste the following link:

mkstevo - 2017-09-16

Many thanks for your kind reply.

I had previously tried to use the WordVariable_H method when storing a Word variable in Eeprom, but failed to get it to work correctly. Having used my long winded method for extracting the byte values from a Word successfully in that instance, I simply "scaled" it up for the additional byte required to give me the maximum value I needed to store in Eeprom.

When I am next at my computer, I will try again using the LongVariable_H, LongVariable_U, LongVariable_E methods and see if I can spot why I couldn't get it to work.

If you would like to refer to this comment somewhere else in this project, copy and paste the following link:

Something is not correct somewhere. Use a Sub to return the value as this always works.

What is very odd is that the first call to print the long value is correct, the, second is incorrect.

Evan

#Option Explicit

#Chip 16F877a,4

'LCD connection settings
#Define LCD_IO 4
#Define LCD_SPEED FAST

#Define LCD_NO_RW

#Define LCD_RS              PortA.0
#Define LCD_Enable      PortA.1

#Define LCD_DB4       PortA.2
#Define LCD_DB5       PortC.0
#Define LCD_DB6       PortC.1
#Define LCD_DB7       PortC.2

'Eeprom location
#Define E_Save        10 'Start of Long(ish) Eeprom locations
                         'Occupies 3 bytes for Hi,Mid and Low

Dim     Long_Saved    As Long
Dim     Long_Returned As Long
Dim     Temp          As Byte

Long_Saved = 0

Do

    Locate 0, 0
    Print "                "
    Locate 1, 0
    Print "                "
    Let Long_Saved = Long_Saved + 135
    PutLEeprom( E_Save, Long_Saved )
    Wait 5 mS
    Locate 0, 0
    Print Long_Saved
    Print " "

    GetLEeprom( E_Save, Long_Returned )
    Locate 1, 0
    Print Long_Returned

    wait 10 ms
Loop

Sub PutLEeprom (HiAddr As Byte, Save_Long As Long) 'Places a Long(ish) into three bytes of
                                                'Eeprom, HiAddr is the first Byte
                                                'location in Eeprom, the lower Bytes
                                                'are placed into the adjacent bytes
        EpWrite (HiAddr,  Save_Long_E)      'The high byte
        EpWrite (HiAddr+1,Save_Long_U)      'The Mid  byte
        EpWrite (HiAddr+2,Save_Long_H)      'The Low  byte
        EpWrite (HiAddr+3,Save_Long)      'The Low  byte

End Sub

Sub GetLEeprom(HiAddr, out EepromVal as long ) 'Takes the address of the High Byte and returns
                                                'a Long(ish) made from the HiAddr and the adjacent
                                                'bytes in Eeprom
    EpRead HiAddr+3, EepromVal
    EpRead HiAddr+2, EepromVal_H
    EpRead HiAddr+1, EepromVal_U
    EpRead HiAddr,   EepromVal_E

End Sub

Since only 24bits are being used, there is no need to write the "E" byte. The code below demos how to write and read a 24bit value to and from EEPROM.

 #chip 18F25K80, 16
 #Config OSC = INTIO2
 #config MCLRE = ON

 #option explicit

 ;----- Define I2C settings - CHANGE PORTS
 #define I2C_MODE Master
 #define I2C_DATA PORTC.4
 #define I2C_CLOCK PORTC.5
 #define I2C_DISABLE_INTERRUPTS ON

  ;----- Set up LCD
  #define LCD_IO 10
  #define LCD_I2C_Address_1 0x7E

 CLS
 Wait 1 s

 '// delcare variables
DIM Var1 as Long
DIM Var2 as Long
DIM Var3 as Long

' // set values to test
Var1 = 11476222
Var2 = 14777810
Var3 = 0'clear

'// write 24 bits Vales to EEPRPoM
EPWRITE_24 0, Var1
EPWRITE_24 3, Var2

'// read stored Var1 back into var3
EPREAD_24 0, Var3
Locate 0,0 : Print Var3

'read stored var2 back into Var3
Var3 = 0  '//clear variable
EPREAD_24 3, Var3
Locate 1,0 : Print Var3

End

Sub EPWRITE_24 (IN Mem_Loc as Byte, in TMP_LONG as LONG)
      EPWRITE Mem_Loc, TMP_LONG
      EPWRITE Mem_Loc + 1, TMP_LONG_H
      EPWRITE Mem_Loc + 2, TMP_LONG_U
END SUB

SUB EPREAD_24 (IN Mem_Loc as Byte, OUT NewVal as LONG)
     EPREAD Mem_Loc, NewVal
     EPREAD Mem_Loc + 1, NewVal_H
     EPREAD Mem_Loc + 2, NewVal_U
End SUB

Anobium - 2017-09-17

The root cause of the isue has been found and resolved. We have found a long standing issue (2009) where setting the return value of a function by using it as a subroutine parameter did not work. This is the issue that Steve found. The issue only related to the use of a function not a subroutine.

The fix will be included in v0.98.00. Meanwhile, use the subroutine techniques that Bill and I have recommended.

I also have created a few demos based on this posting. Writing and Reading variables has been asked many times, so, I created two test programs (now deoms) and I have adapted Bill's code. These can be adapted by others in GitHub. See https://github.com/Anobium/Great-Cow-BASIC-Demonstration-Sources/tree/master/EEPROM%20Solutions/Save_and_Read_Variables_to_EEPROM

Last edit: Anobium 2017-09-17

If you would like to refer to this comment somewhere else in this project, copy and paste the following link:

mkstevo - 2017-09-17

Hello to you both, and thanks for your suggestions. I won't be able to test any of your suggestions for a few hours, possibly Monday evening at the earliest. Once I've had a chance to test your examples, I'll report back.

I will also look into using the EepromVal_E,EepromVal_U and EepromVal_H type methods of extracting the byte values from the Long. When I last tried using them (on Word values) I possibly misinterpreted the ability to extract the lowest byte value by assigning the Long directly to a Byte, I might have tried to use an alias of something similar to 'EepromVal_L' for the lowest byte.

As I say, thanks for your help so far, I'll report back as soon as I can.

If you would like to refer to this comment somewhere else in this project, copy and paste the following link:

Thanks to all who kindly gave their time in looking at this. It appears as though I found a small bug relating to Long variables being used as parameters in SubRoutines and Functions. I have tested a bug fix version of the compiler which does indeed work as anticipated.

From the release of V0.98 onwards this error regarding Functions should be fixed.

I have to say that using the examples given above, I have been able to tidy my code enourmously, and have been able to increase my storing of a Long value to the full four Byte length allowing me to store values of up to 4+ Billion.

Once again, I'd like to thank everyone's kind contributions.

This code does work as expected on V0.96, and is based on William's and Anobium's suggestions to use a SubRoutine to return the values.

#Option Explicit

#Chip 16F1829, 32

'LCD connection settings
#Define LCD_IO 4
#Define LCD_SPEED FAST

#Define LCD_NO_RW

#Define LCD_RS              PortA.0
#Define LCD_Enable      PortA.1

#Define LCD_DB4       PortA.2
#Define LCD_DB5       PortC.0
#Define LCD_DB6       PortC.1
#Define LCD_DB7       PortC.2

'Eeprom location
#Define E_Save        10 'Start of Long Eeprom locations
                         'Occupies 4 bytes for High, UMid, LMid and Low

Dim     Long_Saved    As Long
Dim     Long_Returned As Long
Dim     Temp          As Byte
Dim     TempR         As Byte

GetLEeprom(E_Save, Long_Saved)
If Long_Saved > 4000000000 Then
   Let Long_Saved = 0
End If

Cls
Locate 0, 11
Print":Save"
Locate 1, 11
Print": Ret"

Do
    If Long_Saved < 917575 Then
       Cls
       Locate 0, 11
       Print":Save"
       Locate 1, 11
       Print": Ret"
    End If

    Let Long_Saved = Long_Saved + 917575
    PutLEeprom(E_Save, Long_Saved)
    Locate 0, 0
    Print Long_Saved

    GetLEeprom(E_Save, Long_Returned)
    Locate 1, 0
    Print Long_Returned
    Wait 1 mS

Loop

Sub PutLEeprom (In HiAddr As Byte, In Save_Long As Long) 'Places a Long into four bytes of
                                                'Eeprom, HiAddr is the first Byte
                                                'location in Eeprom, the lower Bytes
                                                'are placed into the adjacent bytes

    Let Temp = Save_Long_E
    EpRead HiAddr,TempR
    If Temp <> TempR Then
        EpWrite (HiAddr  , Temp)    'The High byte
    End If

    Let Temp = Save_Long_U
    EpRead HiAddr+1,TempR
    If Temp <> TempR Then
        EpWrite (HiAddr+1, Temp)    'The UMid  byte
    End If

    Let Temp = Save_Long_H
    EpRead HiAddr+2,TempR
    If Temp <> TempR Then
        EpWrite (HiAddr+2, Temp)    'The LMid  byte
    End If

    Let Temp = Save_Long
    EpRead HiAddr+3,TempR
    If Temp <> TempR Then
        EpWrite (HiAddr+3, Temp)    'The Low  byte
    End If

End Sub

Sub GetLEeprom (In HiAddr As Byte, Out EepromVal As Long) 'Takes the address of the High Byte and returns
                                             'a Long made from the HiAddr and the adjacent
                                             'bytes in Eeprom

    'The sequence of this 'Rebuild' appears important.
    'The order of Low byte - High must be maintained.
    EpRead HiAddr+3, EepromVal
    EpRead HiAddr+2, EepromVal_H
    EpRead HiAddr+1, EepromVal_U
    EpRead HiAddr,   EepromVal_E

End Sub

Last edit: mkstevo 2017-09-17

Problems storing a Long variable in Eeprom

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Problems storing a Long variable in Eeprom

Problems storing a Long variable in Eeprom

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Problems storing a Long variable in Eeprom