Force Overlap

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AtomSoft

Well-Known Member
Im planning on using USB MSD and also need a huge buffer for when USB isnt used...

If i power the Device VIA USB CABLE then i want to use the USB Buffer for USB MSD STUFF
if i power the device VIA external POWER then i want to use the USB buffer for something else...

How can i create another variable to overlap on USB MSD buffer space ?
 
Im seriously starting to really dislike Microchip PICs.... Linker Files and the such... then NEAR/FAR omg...
 
On PIC32's, I have used malloc() and free() to allocate and free large variables.

Not sure whether it is available or worth it for your PIC, though.
 
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If you mean the 512 byte dataBuffer/FATBuffer. The easiest way to use it would be to create a struture type for your data, create a pointer of that data stucture type and assign the address of the buffer memory you want to use to that pointer. I have not looked at the MSD code but I would guess if you don't use the functions it's internal data buffer memory location should still be free to read or write by other processes.
 
ok having enough space isnt the issue i found out... what could cause this problem with SPRINTF ?



Code: 
        while(1) //FOREVER LOOP
        {
            getstr_uart(Rxdata,5); //GET 5 CHARACTERS ... WORKS as you can see in image
            memset(TxStr,0,20);    //Clears the buffer (works)

            sprintf(TxStr, "Hello %s!\n\r\0",Rxdata); //[B] THIS SETS THE ENTIRE BUFFER TO 0xFF [/B]

            str2uart(TxStr); //Usually works but jumps out and turns on some leds for some reason... 
        }
 
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Is 0xDDC (the location of TXStr) a valid data memory address on your chip?
 
nsaspook said:
Is 0xDDC (the location of TXStr) a valid data memory address on your chip?
Click to expand...

Technically yes... but its clasisfied as USB VARS so im trying to this now:

Code: 
#pragma udata vars
unsigned char TxStr[20];
unsigned char Rxdata[6]={0};
unsigned char Txdata[] = "UART Operational!\n\r\0";
#pragma udata

where vars is GPR1 aka 0x100 to 0x1FF but still i get the same issue... you can see the address changed but all 0xFF still.
 
What happens without the memset(); command?... I'm just wondering if the function is some how changing the pointer to a rom pointer. as that would cause this effect..
 
Same exact thing without the memset() command.... The only good thing ive done is setup the Linker so its in a good location of memory heh



Tried it like:

&TxStr and TxStr no luck...
 
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Just to see if sprintf requires a const rom pointer .... Go into program code and look at code position 0x100 and see if the code is 0xff ---> 0xff;
 
ok my combined code is huge... mainly becase I have ELM CHAN FATFS in this project... when i remove all the FATFS files it works! but when i add the files back it doesnt... even if i dont call any of the functions from fatfs stuff. I dont even have to INCLUDE them... if they are in the project at all it doesnt work. If i remove them from project its ok... WTF!
 
OK.... In the linker script is the var data protected? You may have to unprotect the data if its overlapping....

Oh and by the way Yes that's what I mean't.... the locations are all 0xff... Its as if the sprintf() is reading from rom....
 
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