How to move interrupt vector from FLASH to SRAM when using stm32L476?

[lBley.1]

I want my interrupt handler to run in SRAM since some people seem to claim it is a more predictable solution then flash.

I copied my interrupt handler to SRAM using

__attribute__ ((long_call, section (".RamFunc")))  

I tested the interrupt by toggling a pin in the interrupt

	GPIOC->BSRR = LL_GPIO_PIN_6;
	GPIOC->BRR  = LL_GPIO_PIN_6;

Since the interrupt is triggered at a frequency of 2MHZ I expect to measure a stable 2 MHZ signal at the output of the scope. There was however a lot of jitter in the result.

I figured placing the interrupt vector in SRAM might solve this problem. The steps I have taken to realize this are:

Updating the linker file

  .isr_vectorRAM :
  {
    . = ALIGN(4);
    KEEP(*(.isr_vectorRAM)) /* Startup code */
    . = ALIGN(4);
  } >RAM

Changing the startup file to place Interrupt vector in SRAM using previous linker code

	 .section	.isr_vectorRAM,"a",%progbits
	.type	g_pfnVectorsRAM, %object
`.size	g_pfnVectorsRAM, .-g_pfnVectorsRAM
 
 
g_pfnVectorsRAM:
.word	_estack
	.word	Reset_Handler
	.word	NMI_Handler
	.word	HardFault_Handler
	.word	MemManage_Handler
	.word	BusFault_Handler

Changing VTOR register to vector table address in ram:

#define VECT_TAB_BASE_ADDRESS   SRAM1_BASE      /*!< Vector Table base address field.
                                                     This value must be a multiple of 0x200. */
#define VECT_TAB_OFFSET         0x00000000U 
 
SCB->VTOR = VECT_TAB_BASE_ADDRESS | VECT_TAB_OFFSET;

I verified using build analyzer that the vector table is placed in RAM but the interrupt handler now isn't called anymore since i am not seeing any pulses on the scope.

I have a couple questions about my problem and I was wondering if someone might be able to answer them:

• Is an interrupt running in RAM more predictable then FLASH?
• What is the influence of placing the vector table in RAM instead of FLASH?
• What steps need to be taken to place the interrupt vector in flash since my own solution does not seem to be working.?

[Tesla DeLorean]

2MHz is the problem here, find another way of doing this.

D​epending on overall burden/cost of handler, perhaps a few hundred KHz.

F​or vectors memcpy() to new location with 512 byte alignment, and set SCB->VTOR

[Pavel A.]

.isr_vectorRAM :
  {
    . = ALIGN(4);

ALIGN(4) is not enough for vectors.