8-bit MicrocontrollersのトピックRe: How to copy from ROM to RAM?

How to copy from ROM to RAM?

PW_CTL — Wed, 04 Feb 2009 23:39:29 GMT

Hi,
I am trying to do an i2c flash programmer, and I need to allocate some functions (i2c and flash controllers) on RAM while flash is being upgraded.
I´ve found this FAQ:

http://www.freescale.com/webapp/sps/utils/SingleFaq.jsp?FAQ-27860.xml

which is exactly what I need, but I can´t make the CopyCode function work. Any idea?

Re: How to copy from ROM to RAM?

CompilerGuru — Thu, 05 Feb 2009 01:31:05 GMT

What did not work for you?
How does it fail?
Can you share your attempt?
Does your code use runtime routines (check the disassembled code)?

BTW, CopyCode is a section there, not a function.

Daniel

Re: How to copy from ROM to RAM?

PW_CTL — Thu, 05 Feb 2009 01:50:52 GMT

Hi CompilerGuru, and thank you for your fast reply.

 I am following the second method of the

FAQ-27860, and this is the function CopyCode:


void CopyCode(void) {
 char *src, *dest;
 long size;
 src=(char *)ROMCodeToCopy;
 dest = (char *)_START_CopiedToRAM;
 size = _END_CopiedToRAM - _START_CopiedToRAM;
 if (dest != src)
 while (size--)
 *dest++ = *src++;
 }


The problem is that this function uses next variables (should be defined as "far" to write in RAM):

 extern char far ROMCodeToCopy[];
extern char far  _START_CopiedToRAM[];
extern char far  _END_CopiedToRAM[];
extern unsigned long far SizeCodeToCopy[];

but that variables causes a link error: "L1822: Symbol

ROMCodeToCopy in file ...

is undefined" (they aren´t!)


Is there any other method to run code from RAM?
How can I see if my code uses runtime routines?
I am using Codewarrior Version 6.2.

Re: How to copy from ROM to RAM?

bigmac — Thu, 05 Feb 2009 08:00:28 GMT

Hello,

The following code seems quite similar to yours, and does compile. The .PRM file also need to incorporate a special segment for the RAM routines to specify the RELOCATE_TO address. Not sure why you needed to use the far modifier.

extern char __SEG_START_FLASH_ROUTINES[];
extern char __SEG_SIZE_FLASH_ROUTINES[];

/*****************************************************************************/
#pragma CODE_SEG FLASH_ROUTINES

// RAM based function here

#pragma CODE_SEG DEFAULT
/**********************************************************************/
/* Copies Flash_Cmd() function into RAM, using steps documented in Tech
   Note 228
   Start_data refers to the begining of the flash block to be copied.
*/
#define Start_data   __SEG_START_FLASH_ROUTINES
#define Size_data    __SEG_SIZE_FLASH_ROUTINES

void CopyInRAM(void)
{
   char *srcPtr, *dstPtr;
   int count;

   srcPtr = (char *)Start_data;
   dstPtr = (char *)(void *)&Flash_Cmd;
   for (count = 0; count < (int)Size_data; count++) {
      *dstPtr = *srcPtr;
      dstPtr++;
      srcPtr++;
   }
}

Here is the modified .PRM file -

/* Linker parameter file for the GB60 */
NAMES END

SEGMENTS
    ROM          = READ_ONLY    0x182C TO 0xFFAF;
    Z_RAM        = READ_WRITE   0x0080 TO 0x00FF;
    RAM        = READ_WRITE   0x0100 TO 0x0FFF;
    SSTACK       = READ_WRITE   0x1000 TO 0x107F;
    ROM1         = READ_ONLY    0x1100 TO 0x17FF;
    ROM2         = READ_ONLY    0xFFC0 TO 0xFFCB;
    FLASH_TO_RAM = READ_ONLY    0x1080 TO 0x10FF RELOCATE_TO 0x1000;
END

PLACEMENT
    DEFAULT_RAM                         INTO RAM;
    DEFAULT_ROM, ROM_VAR, STRINGS       INTO ROM;
    _DATA_ZEROPAGE, MY_ZEROPAGE         INTO Z_RAM;
    FLASH_ROUTINES                      INTO FLASH_TO_RAM;
END

ENTRIES
END

STACKTOP 0x107F

//VECTOR 0 _Startup /* Reset vector: Default entry point for application. */

Regards,
Mac

Re: How to copy from ROM to RAM?

CompilerGuru — Thu, 05 Feb 2009 14:31:55 GMT

Which chip are you targeting?
out of FAQ-27860:
> With CodeWarrior's Coldfire ...
so this FAQ targets coldfire. However you asked this question in the 8-Bit MCU forum. CF has a few more bits :smileyhappy:.

If you are targeting an HC08/S08/HC12, then follow bigmacs suggestions.
For CF, the identifier have to be defined in the lcf file, so make sure you did all the modifications in there as described in the FAQ.

Daniel

Re: How to copy from ROM to RAM?

PW_CTL — Thu, 05 Feb 2009 16:27:04 GMT

Thanks, Mac and Daniel.

I´m using a MC9SO8SH8.

Re: How to copy from ROM to RAM?

PW_CTL — Thu, 05 Feb 2009 17:21:19 GMT

BigMac, only a question about your code:

void CopyInRAM(void)
{
   char *srcPtr, *dstPtr;
   int count;

   srcPtr = (char *)Start_data;
   dstPtr = (char *)(void *)&Flash_Cmd;
   for (count = 0; count < (int)Size_data; count++) {
      *dstPtr = *srcPtr;
      dstPtr++;
      srcPtr++;
   }
}

What is Flash_Cmd? This way, you are copying one function into RAM, but are you running the code from RAM?.

Thank you for your help.

Re: How to copy from ROM to RAM?

CompilerGuru — Thu, 05 Feb 2009 23:05:26 GMT

For the S08, only part of the referenced FAQ applies, especially the S08 does not use lcf's but prm's for the layout definition.

The topic how to execute code from ram got discussed in this forum quite a few times, for example:

http://forums.freescale.com/freescale/board/message?board.id=8BITCOMM&message.id=3483&query.id=9333#M3483

(I searched for CopyInRAM appears to be a commonly used name for this task :smileyhappy:.

Daniel

Re: How to copy from ROM to RAM?

PW_CTL — Thu, 05 Feb 2009 23:22:20 GMT

Thank you for your help. This technical notes are exactly what i need.

Re: How to copy from ROM to RAM?

bigmac — Fri, 06 Feb 2009 06:18:22 GMT

Hello,

The function flash_Cmd() is the RAM based function code that is copied from flash, and is run from RAM. As indicated in my previous post, to place the code at the required flash location, the function code must be preceeded by -
#pragma CODE_SEG FLASH_ROUTINES

Regards,
Mac

Message Edited by bigmac on 2009-02-06 09:22 AM

Re: How to copy from ROM to RAM?

PW_CTL — Mon, 09 Feb 2009 18:06:28 GMT

Hi again. Finally, the functions seems to be working, but when I execute a flash erase (it executes from RAM), I lost my variables stored in RAM.

I tried to define a new sector in RAM to allocate my variables, but it causes a compilation error. Have you ever hear that error? Is it possible to allocate a variable on a specific sector of the RAM?

Re: How to copy from ROM to RAM?

bigmac — Mon, 09 Feb 2009 21:27:15 GMT

Hello,

Which variables are being over-written? Are they local variables on the stack, or global/static variables?

Have you allowed a sufficient block size within the .PRM file to fully accommodate the RAM function without too much excess? What is the RELOCATE_TO address in RAM? If using a method similar to my previous post, the whole block size will be copied to RAM, independent of the size of the actual function code.

Do you have any large array variables declared within main()? These will permanently occupy stack space and will cause downward stack growth. If they are large, it may be better to handle these as globals.

I suspect that the variables are probably being over-written during the copy process. Perhaps post your PRM file contents to give a better idea of your problem and its solution.

Regards,
Mac

Re: How to copy from ROM to RAM?

PW_CTL — Mon, 09 Feb 2009 22:49:02 GMT

You said

"Are they local variables on the stack, or global/static variables?"

I think here is the key, because I have changed this variables (local) to static ones (global) and the program is working now!

Thanks for your help.

Re: How to copy from ROM to RAM?

bigmac — Tue, 10 Feb 2009 12:02:37 GMT

Hello,

There may still be a potential problem if the copy function is over-writing a portion of the stack, and the stack size is not sufficiently large.

Regards,
Mac

Re: How to copy from ROM to RAM?

PW_CTL — Wed, 11 Feb 2009 00:52:01 GMT

Yes, I´ve checked it, and the stack is big enough.

Finally, my program is allocated in three memory blocks. One of them is for the general code (main function...), a second one is for the i2c functions and the last one is for the flash functions, which are also allocated in ram.

I need the i2c functions working while I am programming the first block, but this functions are too big to be allocated in ram. Could it suppose a problem? It there any restriction on that?. Can I erase one sector of the flash and after that execute the code of other sector?

Thanks for your help.

Re: How to copy from ROM to RAM?

bigmac — Thu, 12 Feb 2009 00:46:50 GMT

Hello,

The 'SH8 device has only a single flash array, so the entire flash memory is not accessible at the point where programming (or erase) occurs, when the internal charge pump is operative. The IIC peripheral hardware should remain operative, however the data cannot be accessed using flash based code, until the programming process is completed.

I would suggest that you do not use burst programming mode, but program a single byte at a time. This way IIC operations can possibly be interleaved between the programming of each byte.

Regards,
Mac

Re: How to copy from ROM to RAM?

PW_CTL — Thu, 12 Feb 2009 02:30:20 GMT

I can´t program byte by byte because it´s too unsecure (there are other devices on my board using iic). I send the .s19 file line by line, and only if the checksum is correct this line is writed.

Anyway, I have put a long delay (about 5 seconds) after a flash writing, and the program fails as soon as I try to run a function located on flash (IIC functions to send an ack, this functions are located at the end of the flash, and i have written only in the first sector).

Should I have to do something after a flash writing to return to "normal mode" after running flash functions (flash functions are executed from ram) ?

Re: How to copy from ROM to RAM?

bigmac — Thu, 12 Feb 2009 23:51:13 GMT

Hello,

I do not know why you believe that byte by byte flash programming is more "unsecure" than burst programming. The only difference that I am aware of is a marginally shorter duration for burst programming.

Does the MCU operate as the IIC master or slave device? If a master, the delays associated with programming/erase operations should be readily accommodated since the master has complete control over IIC operation.

An IIC slave would be more problematic. However, slave operation would also appear incompatible with the presence of more than one external IIC device.

Regards,
Mac

Re: How to copy from ROM to RAM?

PW_CTL — Tue, 17 Feb 2009 02:15:34 GMT

Hi, bigmac.

I have been doing some test and here are the results.

Right now, I have been programming in flash strings of bytes, but I have been doing it byte by byte always. After your last message, I have modified my code to read a byte via IIC and move it to the flash. Here is the function to program a byte on the flash:

#pragma CODE_SEG FLASH_ROUTINES
unsigned char Flash_Cmd(unsigned int FlashAddress, unsigned int FlashDataCounter, unsigned char* pFlashDataPtr, unsigned char FlashCommand)
{
    /* Check to see if FACCERR or PVIOL is set */
    if (FSTAT&0x30)
    {
        /* Clear Flags if set*/
        FSTAT = FSTAT | 0x30;
    }

    if (FlashDataCounter)
    {
      do
      {
          /* Wait for the Last Busrt Command to complete */
          while(!(FSTAT&0x80));

          /* Write Data into Flash*/
          (*((volatile unsigned char *)(FlashAddress++))) = *pFlashDataPtr;
          pFlashDataPtr++;
          /* Write Command */
          FCMD = FlashCommand;
          _asm NOP;
          _asm NOP;
          _asm NOP;
          _asm NOP;

          /* Put FCBEF at 1 */
          FSTAT = 0x80;
          /* Check if Flash Access Error or Protection Violation Error are Set */
          if (FSTAT&0x30)
          {
            /* If so, finish the function returning 1 to indicate error */
            return (1);
          }
      }while (--FlashDataCounter);
    }
    /* wait for the last command to complete */
    while ((FSTAT&0x40)==0);

    /* Return zero to indicate that the function executed Ok */
    return (0);
}

#pragma CODE_SEG DEFAULT

#define Flash_Program(Address, Data) \
          Flash_Cmd((unsigned int)Address, (unsigned int)1, (unsigned char*)&Data, FLASH_PROGRAM_CMD)

My MCU is the slave, and the master does not support holding the scl line to make a pause.

I tried next code:

DisableInterrupts;
Flash_Erase(0xC000);

for (tmp4=0;tmp4<0xff;tmp4++)
        Flash_Program(0xC000 + tmp4, tmp4);
tmp4=0;
EnableInterrupts;

And it works succesfully, but when I tried:
        while (!I2C1_GetCharsInRxBuf()){}
        if(I2C1_RecvChar(&tmp4)==ERR_OK) { //Numero de bytes que se van a recibir
        I2C1_ClearRxBuf();
        DisableInterrupts;
        Flash_Erase(0xC000);
        EnableInterrupts;
        for (tmp5=0;tmp5<tmp4;tmp5++){    //Bucle a esos bytes
          while (!I2C1_GetCharsInRxBuf()){}
          if(I2C1_RecvChar(&tmp3)==ERR_OK) {
            if(I2C1_RecvChar(&tmp3));
            I2C1_ClearRxBuf();
            DisableInterrupts;
            Flash_Program(0xC000 + tmp5, tmp3);
            EnableInterrupts;

          }
        }

It is basically the same code reading data via IIC and waiting for every byte. This code fails, and disconnects the debugger after erasing the rom. It´s needed to reprogram again. Each IIC byte has a delay of 1 second. Right now, I have no idea about what´s wrong...
IIC functions are located on a specific "partition" of the ROM, which is never flashed.

Any suggestion?

Re: How to copy from ROM to RAM?

bigmac — Tue, 17 Feb 2009 08:13:22 GMT

Hello,

I suspect that the COP timer is timing out whilst waiting to receive an IIC data byte. The COP timer will need to be cleared within the wait loop.

Regards,
Mac