STM32F10x interrupt issues

Defining 128KB of RAM is inviting disaster if you only have 48 KB (0xC000, ie 0x20000000..0x2000BFFF)

Clive, thank you for your reply.

void HardFault_Handler(void)
{
static char msg[80];
printErrorMsg(''In Hard Fault Handler
'');
sprintf(msg, ''SCB->HFSR = 0x%08x
'', SCB->HFSR);
printErrorMsg(msg);
if ((SCB->HFSR & (1 << 
30
)) != 0) {
printErrorMsg(''Forced Hard Fault
'');
sprintf(msg, ''SCB->CFSR = 0x%08x
'', SCB->CFSR );
printErrorMsg(msg);
if((SCB->CFSR & 0xFFFF0000) != 0) {
printUsageErrorMsg(SCB->CFSR);
}
}
stackDump((uint32_t *)(__get_PSP()));
__ASM volatile(''BKPT #01'');
/* Go to infinite loop when Hard Fault exception occurs */
while (1) { }
}

You really should review the .MAP file and understand what you have in RAM. If the linker fails it thinks stuff should be in RAM. You've clearly oversubscribed the available RAM

Ok, I'll make sure that all the constants are really static consts and check the linker map.

Well, I did that and reduced some temporary structure sizes, but I still have the Hard Fault upon reading or writing of any global variable from an IRQ handler. Here's an excerpt of the linker map file. Any access here from a function called from within the EXTI0 which I posted earlier, or for that matter any other Data Gb goes to HardFault.

SPI_InitStructure 0x200068ac 0x14 Data Gb main.o [2]
SPI_MASTER_Buffer_Rx 0x200068c0 0xc Data Gb main.o [2]
SPI_MASTER_Buffer_Tx 0x20004bb0 0xc Data Gb main.o [2]

/*ADC and SPI read and write buffers - used in directed transfers */
uint8_t SPI_MASTER_Buffer_Tx[MAX11040_PacketSize]={0};
uint8_t SPI_MASTER_Buffer_Rx[MAX11040_PacketSize]={0};

/**/
extern uint8_t * SPI_MASTER_Buffer_Rx;
extern uint8_t * SPI_MASTER_Buffer_Tx;

uint8_t MaxAdcManiReg(SPI_group* GSPIx, uint8_t *ibuffer, uint16_t len, uint8_t* obuffer, uint8_t command)
{
uint8_t status;
uint16_t i;
/*Select SPI device*/
GPIO_ResetBits(GSPIx->GPIO[0],GSPIx->Pins[S_SS]);
/* Send the command with the address */
status = MaxAdcSendByte(GSPIx->SPIP, command );
/* Read LEN bytes */
if( len!=0 ) 
{for(i=0; i<
len
; i++) 
{ibuffer[i]=MaxAdcSendByte(GSPIx->SPIP, obuffer[i] );}
}
GPIO_SetBits(GSPIx->GPIO[0],GSPIx->Pins[S_SS]);
return status;
}

static uint8_t MaxAdcSendByte(SPI_TypeDef* SPIx, uint8_t b)
{
/* Loop while DR register in not empty */
while (SPI_I2S_GetFlagStatus(SPIx, SPI_I2S_FLAG_TXE) == RESET);
/* Send byte through the SPI peripheral */
SPI_I2S_SendData(SPIx, b);
/* Wait to receive a byte */
while (SPI_I2S_GetFlagStatus(SPIx, SPI_I2S_FLAG_RXNE) == RESET);
/* Return the byte read from the SPI bus */
return SPI_I2S_ReceiveData(SPIx);
}

void Stage0(void)
{ uint32_t result=0; /*TODO for Unity*/
MaxAdcSetup(&MAX11040, result); // going into the call here
while(GPIO_ReadInputDataBit(SPI_MASTER_GPIO_EXT, SPI_MASTER_PIN_DRDY)!=0) {}
/*Read the first 96-bit set of digitized measures*/ 
MaxAdcManiReg(&MAX11040, SPI_MASTER_Buffer_Tx, (uint16_t)MAX11040_DATAREG_SIZE_B, SPI_MASTER_Buffer_Tx, MCMD_R_DATAREG);
}
....
void Stage2()
{
uint32_t result=0; 
MaxAdcSetup(&MAX11040, result); // coming out of the call here
/* Initialize Leds LD1 and LD2 mounted on Datalogger board */
Datalogger_LEDInit(VD2_PIN);
Datalogger_LEDInit(VD1_PIN);
/* Turn the LED on to check on IRQ*/
Datalogger_LEDOn(VD1_PIN);
Datalogger_LEDOn(VD2_PIN);
/*Configure the EXTI 0 line to become active on the falling MAX11040 DRDY edge*/
EXTI0_Config();
IRQ_Config();
Ringbuf_Init(&(RBuffer.b), MaxData,(MAX11040_CHDEPTH+8)>>3,MAX11040_CHANNEL);
NVIC_SetPendingIRQ(EXTI0_IRQn);
EXTI_GenerateSWInterrupt(SPI_MASTER_IRQ);
while(cycles>0) { /*wait for a minute*/ } 
SD_Fulltest();
//*TODO*//
}