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Unable to use AHB Sram when Global Data Placement is not set to default (LPC4357)

Question asked by uaz on Nov 1, 2018
Latest reply on Nov 4, 2018 by uaz


I tried to change the managed linker script option to fully use my SRAMs. I found out that I'm unable to place data in AHB Sram (RAM3) even when using __DATA() macro. This is the situation:


=> INITIAL when my data is correctly placed in RAM3:

1. My memory configuration:

memory configuration

2. My linker setting:

3. Compilation result is correct, my 12KB data is in RamAHB32:


=> AFTER I Changed the Global data placement setting:

1. My linker setting:

2. The new compilation result where my data is placed into RAM instead of RAM3:


Would appreciate if anyone could point my mistake. Here is my test source code:

#include "chip.h"

#include <cr_section_macros.h>
#include <stdint.h>

static volatile __DATA(RAM3) uint8_t ucLwipHeap[12000];

int main(void) {

ucLwipHeap[0] = 123;
ucLwipHeap[5] = 99;

volatile static int i = 0 ;
while(1) {
i++ ;


Thanks in advance,