Writing and Reading Flash

TurnipTruck · August 2008

Greetings,

Getting things on and off the flash is something that still elludes me.

Could someone give me some example code for writing an integer variable value to flash and then reading it back into that integer variable.

Thanks!

AMXJeff · August 2008

You do not need to use VARIABLE_TO_STRING AND STRING_TO_VARIABLE, but I believe this is the best way to write any variable to flash, end of soap box.

DEFINE_VARIABLE
TEST


DEFINE_FUNCTION WriteIntegerFlash(CHAR cFileName[], INTEGER nValue)
{	
	STACK_VAR SLONG slFileHandle;
	STACK_VAR CHAR cConvertedValue[100];
	
	slFileHandle = FILE_OPEN(cFileName, FILE_RW_NEW);
	
	// VALID FILE HANDLE
	IF (slFileHandle > 0)
	{
		VARIABLE_TO_STRING(nValue, cConvertedValue, 1);
		
		FILE_WRITE(slFileHandle, cConvertedValue, LENGTH_STRING(cConvertedValue));
		
		FILE_CLOSE(slFileHandle);
	}
}

DEFINE_FUNCTION INTEGER ReadIntegerFlash(CHAR cFileName[])
{	
	STACK_VAR SLONG slFileHandle;
	STACK_VAR CHAR cConvertedValue[100];
	STACK_VAR INTEGER nValue;
	
	slFileHandle = FILE_OPEN(cFileName, FILE_READ_ONLY);
	
	// VALID FILE HANDLE
	IF (slFileHandle > 0)
	{
		
		FILE_READ(slFileHandle, cConvertedValue, MAX_LENGTH_STRING(cConvertedValue));
		
		STRING_TO_VARIABLE(nValue, cConvertedValue, 1);

		FILE_CLOSE(slFileHandle);
	}
	
	RETURN nValue;
}

DEFINE_PROGRAM

WAIT 100
{
	TEST = TEST + 10;
	
	WriteIntegerFlash('test.dat',TEST);
	
	SEND_STRING 0,"'INTEGER=',ITOA(ReadIntegerFlash('test.dat'))"
	
}

TurnipTruck · August 2008

Good Stuff!!

DEFINE_FUNCTION WriteIntegerToFlash (CHAR cFileName[], INTEGER nValue_)
{
STACK_VAR SLONG slFileHandle
STACK_VAR CHAR cConvertedValue[100]
slFileHandle=FILE_OPEN(cFileName,FILE_RW_NEW)
IF (slFileHandle>0)
    {
    VARIABLE_TO_STRING (nValue_,cConvertedValue,1)
    FILE_WRITE (slFileHandle,cConvertedValue,LENGTH_STRING(cConvertedValue))
    FILE_CLOSE (slFileHandle)
    }
ELSE
    SEND_STRING vdvDVM,"'FLASH FILE WRITE ERROR ',ITOA(slFileHandle)"
}

DEFINE_FUNCTION INTEGER ReadIntegerFromFlash (CHAR cFileName[])
{
STACK_VAR SLONG slFileHandle
STACK_VAR CHAR cConvertedValue[100]
STACK_VAR INTEGER nValue_
slFileHandle=FILE_OPEN (cFileName,FILE_READ_ONLY)
IF (slFileHandle>0)
    {
    FILE_READ (slFileHandle,cConvertedValue,LENGTH_STRING(cConvertedValue))
    STRING_TO_VARIABLE (nValue_,cConvertedValue,1)
    FILE_CLOSE (slFileHandle)
    RETURN nValue_
    }
ELSE
    SEND_STRING vdvDVM,"'FLASH FILE READ ERROR ',ITOA(slFileHandle)"
}
//----------

WriteIntegerToFlash("'CHANNEL',cDeviceNumber,'.dat'",nValue)

nValue=ReadIntegerFromFlash("'CHANNEL',cDeviceNumber,'.dat'")

Above is what I created with your help. Unfortunately, my return value is always zero, although the correct file name is created on the flash. Any suggestions? Thanks!

vining · August 2008

TurnipTruck wrote:

Unfortunately, my return value is always zero,

Well what's the value of nValue when you call the function "WriteIntegerToFlash()". For testing you might want to add some more SEND_STRING 0's or step through it in debugger.

TurnipTruck · August 2008

vining wrote: »

Well what's the value of nValue when you call the function "WriteIntegerToFlash()". For testing you might want to add some more SEND_STRING 0's or step through it in debugger.

It's non-zero (46 to be exact). send strings back to the master result in zero.

Joe Hebert · August 2008

Change this:
FILE_READ (slFileHandle,cConvertedValue,LENGTH_STRING(cConvertedValue))

To this:
FILE_READ (slFileHandle,cConvertedValue,MAX_LENGTH_STRING(cConvertedValue))

Or this:
FILE_READ (slFileHandle,cConvertedValue,100)

And you should be good to go.

When cConvertedValue is declared it has no length so FILE_READ was asking for a max of 0 characters which will get you nowhere fast.:)

TurnipTruck · August 2008

Joe Hebert wrote: »

And you should be good to go.

I'm good to go! Thanks, works like a champ.

Writing and Reading Flash

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