TM4C123GH6PM: #Pragma DATA_SECTION in TM4C123GH6PM

Divyesh Patel

Part Number: TM4C123GH6PM

Hi Everyone,

I am using TM4C123GH6PM controller. I want to store lookup table in FLASH. For that i have used #pragma DATA_SECTION, but during debugging it is giving me warning as described below and i am unable to call the value which i have stored.

Following Sequence i have followed, please guide me if i have missed something or did anything wrong.

1) In tm4c123gh6pm.cmd file

MEMORY
{

CHANNEL0 : origin = 0x20009000, length = 0x0006000

}

SECTIONS
{

.channel0 : {} > CHANNEL0

}

2) In main.c

#pragma DATA_SECTION (pwmlkp, ".channel0")

const unsigned int pwmlkp[18]={86,93,103,115,125,136,145,159,169,181,192,206,216,226,235,245,256,265};

3) Warning during debug

CORTEX_M4_0: GEL Output:
Memory Map Initialization Complete
CORTEX_M4_0: Loader: One or more sections of your program falls into a memory region that is not writable. These regions will not actually be written to the target. Check your linker configuration and/or memory map.

4) Expression Window

[0] unknown Memory map prevented reading 0x20009000

[1] unknown Memory map prevented reading 0x20009004

[17] unknown Memory map prevented reading 0x20009044

over 4 years ago

+1 Chester Gillon over 4 years ago

Guru 92251 points

Divyesh Patel said:
CHANNEL0 : origin = 0x20009000, length = 0x0006000

The TM4C123GH6PM has 32KB of SRAM from addresses 0x20000000 .. 0x20007FFF, and the CHANNEL0 memory region is in a reserved address space as shown by the datasheet::

The CHANNEL0 memory region being in a reserved address space is what leads to the warnings. Also attempts to read or write addresses in reserved spaces result in a bus fault which will cause the program to fail when it attempts to read pwmlkp[].

Divyesh Patel said:
I want to store lookup table in FLASH.

In which case, the CHANNEL0 memory region should be allocated from the memory range for the on-chip flash.

0 Bruce McKenney over 4 years ago

Guru 99105 points

> CHANNEL0 : origin = 0x20009000, length = 0x0006000

Per data sheet (SPMS376E) Table 2-4, this is Reserved, i.e. not any kind of memory. Did you maybe mean:

> CHANNEL0 : origin = 0x00009000, length = 0x0006000

0 Divyesh Patel over 4 years ago in reply to Chester Gillon

Intellectual 805 points

Hi Sir,

Understood, because of out of the range, i am getting warning.

Now i have changed the memory range

CHANNEL0 : origin = 0x00001000, length = 0x0006000.

So, now i am able compile without warning.

But, still i am unable to store data.

I have checked Memory browser its value is FFFFFFFF.

Once, array is stored. Then how to recall/get that array?

0 Ralph Jacobi over 4 years ago in reply to Divyesh Patel

TI__Guru*** 135355 points

Hello Divyesh,

Can you post the full .cmd file here as an attachment so I can review the contents?

0 Divyesh Patel over 4 years ago in reply to Ralph Jacobi

Intellectual 805 points

Hi Sir,

Sure, please find below the details of .cmd file

/******************************************************************************
*
* Default Linker Command file for the Texas Instruments TM4C123GH6PM
*
* This is derived from revision 15071 of the TivaWare Library.
*
*****************************************************************************/

--retain=g_pfnVectors

MEMORY
{
CHANNEL0 : origin = 0x00001000, length = 0x0006000
FLASH (RX) : origin = 0x00012000, length = 0x00040000
SRAM (RWX) : origin = 0x20000000, length = 0x00008000
}

/* The following command line options are set as part of the CCS project. */
/* If you are building using the command line, or for some reason want to */
/* define them here, you can uncomment and modify these lines as needed. */
/* If you are using CCS for building, it is probably better to make any such */
/* modifications in your CCS project and leave this file alone. */
/* */
/* --heap_size=0 */
/* --stack_size=256 */
/* --library=rtsv7M4_T_le_eabi.lib */

/* Section allocation in memory */

SECTIONS
{

.intvecs: > 0x00012000
.text : > FLASH
.const : > FLASH
.cinit : > FLASH
.pinit : > FLASH
.init_array : > FLASH

.channel0 : {} > CHANNEL0

.vtable : > 0x20000000
.data : > SRAM
.bss : > SRAM
.sysmem : > SRAM
.stack : > SRAM

}

__STACK_TOP = __stack + 512;

0 Ralph Jacobi over 4 years ago in reply to Divyesh Patel

TI__Guru*** 135355 points

Hello Divyesh,

You need to indicate what permissions this section of memory should have in your definition:

CHANNEL0 : origin = 0x00001000, length = 0x0006000

See how it is done for Flash:

FLASH (RX) : origin = 0x00012000, length = 0x00040000

R is for Read, X is for Execute, and W is for Write.

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TM4C123GH6PM: #Pragma DATA_SECTION in TM4C123GH6PM