SRAM low power mode

[ebarker]

Posted on October 12, 2006 at 06:14

SRAM low power mode

[ebarker]

Posted on May 17, 2011 at 09:33

I have a Keil MCBSTR912 board and a REVA STR912 board and am having the same problem on both.

I hook a battery to the processor VBATT pin, and remove the power from the board. When you hook power back up, it reboots and clears the memory variables when I think it shouldn't.

So it doesn't look like the VBATT SRAM thing is working. Any suggestions ??

#include ''91x_lib.h''

#include ''main.h''

GPIO_InitTypeDef GPIO_InitStructure;

static unsigned char display_byte;

static int delaycnt;

int main()

{

// //////////////////////////////////////////////////////////////////////////////////////////////////////

SCU_APBPeriphClockConfig(__GPIO7, ENABLE);

// GPIO7 goes to the LEDs

GPIO_DeInit(GPIO7);

GPIO_StructInit(&GPIO_InitStructure);

GPIO_InitStructure.GPIO_Pin = GPIO_Pin_All;

GPIO_InitStructure.GPIO_Direction = GPIO_PinOutput;

GPIO_InitStructure.GPIO_Type = GPIO_Type_PushPull;

GPIO_InitStructure.GPIO_IPConnected = GPIO_IPConnected_Disable;

GPIO_InitStructure.GPIO_Alternate = GPIO_OutputAlt1;

GPIO_Init(GPIO7, &GPIO_InitStructure);

// //////////////////////////////////////////////////////////////////////////////////////////////////////

SCU_APBPeriphClockConfig(__RTC,ENABLE);

RTC_DeInit();

RTC_SRAMBattPowerCmd(ENABLE);

// //////////////////////////////////////////////////////////////////////////////////////////////////////

while (1)

{

for (delaycnt = 0; delaycnt < 500000; delaycnt++); // sleep

GPIO_Write(GPIO7, display_byte++);

}

}

[stefano239955_stm1_stmicro]

Posted on May 17, 2011 at 09:33

Hi,

Check if the compiler initialize the ram.

I'm using IAR. In the init code the allocated memory is filled with 0

if the variable is not initilized.

I think that your variables are zeroed during the init sequence.