8-bit Microcontrollers中的主题 Re: sprintf Problem

sprintf Problem

PabloA — Tue, 29 May 2007 23:46:06 GMT

Hello to every body!

I'm new in the forum and I have a little problem with my C code for a MC908QB8 microcontroller.

I try to use "sprintf " like this:

#include <hidef.h> /* for EnableInterrupts macro */
#include <stdio.h>
#include "derivative.h" /* include peripheral declarations */

void main(void)
{

char Str_Buffer [10] ;
signed int Num = 1500;

(void) sprintf (Str_Buffer, "%d", Num);

for(;
{
__RESET_WATCHDOG(); /* feeds the dog */
} /* loop forever */
/* please make sure that you never leave this function */

}

But wen I try to simulate it the Real Time Debugger Stop with the following mensage:

Error: At location 0002 -
Error: Attempt to use unimplemented (--) memory.

Im not using floating point.

I don't understand way it dosen't work, so if any body can help me I will appreciate it.

Thank you very much!

Pablo Suarez

Re: sprintf Problem

CompilerGuru — Wed, 30 May 2007 02:36:07 GMT

Hi,

the problem is the too small stack. A wizard generated projects allocates 0x30 bytes for the stack, but that sprintf did use 0x43 bytes for me (HC08 V5.1, SMALL memory model, default options).

Here an adapted prm file providing 0x60 bytes for the stack.

Daniel

Code:

/* This is a linker parameter file for the QB8 */NAMES END /* CodeWarrior will pass all the needed files to the linker by command line. But here you may add your own files too. */SEGMENTS /* Here all RAM/ROM areas of the device are listed. Used in PLACEMENT below. */    ROM                      =  READ_ONLY    0xDE00 TO 0xFDFF;    Z_RAM                    =  READ_WRITE   0x0040 TO 0x00DF;    SSTACK_AREA              =  READ_WRITE   0x00E0 TO 0x013F;    ROM1                     =  READ_ONLY    0xFFB0 TO 0xFFBD;    ROM2                     =  READ_ONLY    0xFFC2 TO 0xFFCF;ENDPLACEMENT /* Here all predefined and user segments are placed into the SEGMENTS defined above. */    SSTACK                                      INTO  SSTACK_AREA;    DEFAULT_ROM, ROM_VAR, STRINGS               INTO  ROM; /* ROM1,ROM2 In case you want to use ROM1,ROM2 as well, be sure the option -OnB=b is passed to the compiler. */    DEFAULT_RAM,_DATA_ZEROPAGE, MY_ZEROPAGE     INTO  Z_RAM;ENDSTACKSIZE 0x60VECTOR 0 _Startup /* Reset vector: this is the default entry point for an application. */

Re: sprintf Problem

PabloA — Wed, 30 May 2007 03:11:20 GMT

Thak you very much CompilerGuru you are right!

Re: sprintf Problem

Lundin — Wed, 30 May 2007 13:43:23 GMT

On a mcu with limited memory, and possibly demands on realtime performance, you might want to concider writing your own int-to-ASCII routine instead of using sprintf(). sprintf() will not only give you RAM problems, but it will also slaughter the flash. Ahe function is also very slow, with a huge amount of overhead you don't need.

No matter the platform, the only reason to use sprintf() is really when you are using float numbers, since that will be time and memory consuming no matter how you do. For simple integer to ASCII conversions, there are much smoother ways.

Re: sprintf Problem

bigmac — Wed, 30 May 2007 21:14:48 GMT

Hello,

It is my understanding that the simulation error occurred because the stack attempted to exceed the boundary

of the segment used by the stack, and not when the STACKSIZE parameter was exceeded. Had the boundary

not been exceeded, but more than the STACKSIZE limit used, an error would not have been reported, but

serious problems could still potentially occur.

It would appear that the default PRM file generated by CW, specifically for the HC908QB8 device, has

significant shortcomings for all but the simplest of projects. The following is the default arrangement

generated by CW.

/* This is a linker parameter file for the QB8 */

NAMES END

SEGMENTS
    ROM                      = READ_ONLY    0xDE00 TO 0xFDFF;
    Z_RAM                    = READ_WRITE   0x0040 TO 0x00FF;
    RAM                      = READ_WRITE   0x0100 TO 0x013F;
    ROM1                     = READ_ONLY    0xFFB0 TO 0xFFBD;
    ROM2                     = READ_ONLY    0xFFC2 TO 0xFFCF;
END

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

STACKSIZE 0x30

VECTOR 0 _Startup

Because there is no segment specifically allocated to the stack, the stack automatically becomes allocated to

DEFAULT_RAM. Additionally, any global variables are also allocated to DEFAULT_RAM. This means that,

by default, the stack and any global variables must share a total of only 64 bytes, with every chance that the

variables will be over-written by the stack, without any warning whatsoever.

Daniel's alternative PRM neatly solves this problem by providing an explicit segment for the stack, and by

DEFAULT_RAM being allocated to the Z_RAM segment. Thus there is much wider separation between the

global variables and the stack, and a simulation error should occur if the stack usage exceeds its segment

boundary. The STACKSIZE value would appear unimportant if using a separate stack segment.

The alternative PRM would seem a much better default arrangement for the QB8 device, to suit a wider

variety of projects.

I totally agree with Lundin's comments concerning use of sprintf() - more than 1.5K just for that function, in

a device with 8K total flash - very expensive! I recall that there are other threads within this forum that address

binary-to-BCD conversions. These should be easily adapted for 16-bit binary-to-ASCII.

Regards,

Mac

Re: sprintf Problem

Lundin — Fri, 01 Jun 2007 16:31:43 GMT

Actually... since the algo is pretty simple, here you go, no charge:

void gpfunc_getDecStr (uint8* str, uint8 len, uint32 val)
{
uint8 i;

for(i=1; i=len; i++)
{
str[len-i] = val % 10 + '0';
val /=10;
}
str[i-1]='\0';
}

On a HCS12 this gave 80 bytes instead of 1500 bytes. A slight improvement...

Re: sprintf Problem

PabloA — Thu, 07 Jun 2007 00:27:54 GMT

Thak you very much all of you.

I'll try Lundin's code!

Best regards

Pablo