Code is broken once compile with optimisation enabled

Hi all,

I have uploaded those important of part of the codes here to have expert review on where my code causing the compiler interpret wrongly when Optimisation is enabled.

I have tested the code with Compile with none optimisation and it works without an issue but it start to broken even if I select the optimisation -o1.

So basically what my code is doing is, I am using DMA2 Stream2 to send data from memory to GPIOE->ODR register. I have enable only 1 interrupt (which is caused by both edge changes on Channel2) to change the value in the variable and re-enable the DMA2 Stream2 again for the next edge.

In the main.c while loop, I generated a simulated 10uS pulse and expected an interrupt and DMA stream happen at the same time.

Without Optimisation Enable, the code works as expected.

With Optimisation, -O1, interrupt works but no DMA2 after the 1st edge change. Suspect the optimisation has screw up the code in the interrupt.

Please kindly help to suggest how to code for optimisation enable?

Appreciate your help. Thank you.

In the main.c

/* Private user code ---------------------------------------------------------*/
/* USER CODE BEGIN 0 */
uint32_t GPIOE_IDR_buff;
uint32_t GPIOE_BSRR_buff;
uint32_t GPIOE_ODR_buff;
uint32_t GPIOE_ODR_DataHI;
uint32_t toggle;
/* USER CODE END 0 */
 
int main(void)
{
 /* USER CODE BEGIN 1 */
 GPIOE_IDR_buff = 0;
 GPIOE_BSRR_buff = (uint32_t)GPIB_D0_Pin << 16U;;
 GPIOE_ODR_buff = 0x80FF; //Set PIN15 HI during Testing
 GPIOE_ODR_DataHI = 0x00FF;
 toggle = 0;
 /* USER CODE END 1 */
 
 
 /* MCU Configuration--------------------------------------------------------*/
 
 /* Reset of all peripherals, Initializes the Flash interface and the Systick. */
 HAL_Init();
 
 /* USER CODE BEGIN Init */
 /*****************************************************************************
 *
 * /CS = TIM1 - CC Chn2 + DMA + Interrupt
 * /RD = TIM1 - CC Chn3 + DMA
 * /WR = Digital Input (no pull-up)
 * RS2 - RS0 = Digital Input (no pull-up)
 * D7 - D0 = Digital Output (Open Drain)
 *
 ****************************************************************************/
 /* USER CODE END Init */
 
 /* Configure the system clock */
 SystemClock_Config();
 
 /* USER CODE BEGIN SysInit */
 
 /* USER CODE END SysInit */
 
 /* Initialize all configured peripherals */
 MX_GPIO_Init();
 MX_DMA_Init();
 MX_TIM1_Init();
 MX_TIM12_Init();
 /* USER CODE BEGIN 2 */
 
 /*****************************************************************************
 *
 * Configure IO for GPIB
 * /CS on TIM1_Chn2.
 * - TIM1_Chn2 trigger the TIM1_CC_IRQHandler
 * - TIM1_Chn2 DMA activates to Initialise GPIOE
 *
 * /RD on TIM1_Chn3.
 * - TIM1_Chn3 DMA activates the transfer from GPIOE_ODR_buff to GPIOE_ODR
 * - Enable only valid CS signal
 *
 * /CS on TIM1_Chn4
 * - TIM1_Chn4 DMA activates by software to read GPIOE IDR
 *
 ****************************************************************************/
 /*****************************************************************************
 * Step 1: Configure & Enable DMA
 ****************************************************************************/
 HAL_DMA_Start(htim1.hdma[TIM_DMA_ID_CC2],
 (uint32_t)&GPIOE_ODR_buff,
 (uint32_t)&GPIB_D0_GPIO_Port->ODR, 1);
 /*****************************************************************************
 * Step 2: Start Comparators
 * - Chn2 = CS with DMA event + Interrupt
 * - Chn3 = RD with DMA event
 * - Chn4 = GND with software DMA event
 ****************************************************************************/
 __HAL_TIM_ENABLE_IT(&htim1, TIM_IT_CC2);
 TIM_CCxChannelCmd(htim1.Instance, TIM_CHANNEL_2, TIM_CCx_ENABLE);
 
 /*****************************************************************************
 * Step 3: ENABLE TIM1 DMA Request on CHN2,4 (Last)
 ****************************************************************************/
 __HAL_TIM_ENABLE_DMA(&htim1, TIM_DMA_CC2);
 
 /*****************************************************************************
 * Step 4: Start TIM1
 ****************************************************************************/
 htim1.Instance->SR = 0x00;
 __HAL_TIM_ENABLE(&htim1);
 
 /*****************************************************************************
 * TIM12
 * - Use in the delay_uS() to give a precise delay in uS resolution
 ****************************************************************************/
 __HAL_TIM_ENABLE(&htim12);
 
 
 /* USER CODE END 2 */
 
 /* Infinite loop */
 /* USER CODE BEGIN WHILE */
 while (1)
 {
 /* USER CODE END WHILE */
 
 /* USER CODE BEGIN 3 */
 
 //delay 1mS
 delay_us(10);
 dma_syc_sig_GPIO_Port->BSRR = dma_syc_sig_Pin;
 
 //delay 1mS
 delay_us(10);
 dma_syc_sig_GPIO_Port->BSRR = (uint32_t)dma_syc_sig_Pin << 16U;
 }
 /* USER CODE END 3 */
}

In the main.h

extern uint32_t GPIOE_IDR_buff;
extern uint32_t GPIOE_ODR_buff;
extern uint32_t toggle;

In the stm32f4xx_it.c

extern TIM_HandleTypeDef htim1;
 
void TIM1_CC_IRQHandler(void)
{
 /* USER CODE BEGIN TIM1_CC_IRQn 0 */
 
 //htim1.Instance->SR = 0x00;
 if (toggle)
 {
 toggle = 0;
 GPIOE_ODR_buff = 0x80FF;
 }
 else
 {
 toggle = 1;
 GPIOE_ODR_buff = 0x00FF;
 }
 
 //Enable DMA again for the next triggers
 //Copy the value in the buff into DMA Stream memory
 //So changes on buff will not affect the value sent from DMA
 DMA2->LIFCR = DMA_LIFCR_CTCIF2|DMA_LIFCR_CHTIF2|DMA_LIFCR_CTEIF2|DMA_LIFCR_CDMEIF2; //Clear DMA2S2 flag
 __HAL_DMA_ENABLE(htim1.hdma[TIM_DMA_ID_CC2]);
 
 htim1.Instance->SR = 0x00;
 
 return;
}