STM32H723- DMA DAC only works with const only? - stm32

Question

In a STM32G4, I was able to setup the DAC DMA such that I could use a regular variable (ie. a uint8_t array). However, when I tried porting my code over to an H723, the DAC DMA would not work unless it's with a constant variable (ie. a const uint8_t array) that is set before runtime. My application requires runtime changes to the array. A pointer initialization of the array does not seem to work. I was wondering if there is a way to remedy this? Am I stuck with the constant variable? Thank you!
EDIT1: Current Setup of DAC DMA and TIMER
static void MX_DAC1_Init(void){
DAC_ChannelConfTypeDef sConfig = {0};
hdac1.Instance = DAC1;
if (HAL_DAC_Init(&hdac1) != HAL_OK){
Error_Handler();
}
sConfig.DAC_SampleAndHold = DAC_SAMPLEANDHOLD_DISABLE;
sConfig.DAC_Trigger = DAC_TRIGGER_T15_TRGO;
sConfig.DAC_OutputBuffer = DAC_OUTPUTBUFFER_DISABLE;
sConfig.DAC_ConnectOnChipPeripheral = DAC_CHIPCONNECT_ENABLE;
sConfig.DAC_UserTrimming = DAC_TRIMMING_FACTORY;
if (HAL_DAC_ConfigChannel(&hdac1, &sConfig, DAC_CHANNEL_2) != HAL_OK)
{
Error_Handler();
}
}
Timer15 Config:
static void MX_TIM15_Init(void)
{ TIM_ClockConfigTypeDef sClockSourceConfig = {0};
TIM_MasterConfigTypeDef sMasterConfig = {0};
htim15.Instance = TIM15;
htim15.Init.Prescaler = 55-1;
htim15.Init.CounterMode = TIM_COUNTERMODE_UP;
htim15.Init.Period = 10-1;
htim15.Init.ClockDivision = TIM_CLOCKDIVISION_DIV1;
htim15.Init.RepetitionCounter = 0;
htim15.Init.AutoReloadPreload = TIM_AUTORELOAD_PRELOAD_ENABLE;
if (HAL_TIM_Base_Init(&htim15) != HAL_OK)
{
Error_Handler();
}
sClockSourceConfig.ClockSource = TIM_CLOCKSOURCE_INTERNAL;
if (HAL_TIM_ConfigClockSource(&htim15, &sClockSourceConfig) != HAL_OK)
{
Error_Handler();
}
sMasterConfig.MasterOutputTrigger = TIM_TRGO_UPDATE;
sMasterConfig.MasterSlaveMode = TIM_MASTERSLAVEMODE_DISABLE;
if (HAL_TIMEx_MasterConfigSynchronization(&htim15, &sMasterConfig) != HAL_OK)
{
Error_Handler();
}
}
DMA Config:
static void MX_DMA_Init(void){
__HAL_RCC_DMA1_CLK_ENABLE();
HAL_NVIC_SetPriority(DMA1_Stream5_IRQn, 0, 0);
HAL_NVIC_EnableIRQ(DMA1_Stream5_IRQn);
/* DMAMUX1_OVR_IRQn interrupt configuration */
HAL_NVIC_SetPriority(DMAMUX1_OVR_IRQn, 0, 0);
HAL_NVIC_EnableIRQ(DMAMUX1_OVR_IRQn);
}
in the main function:
int main(void){
MX_DAC1_Init();
MX_TIM15_Init();
MX_OPAMP2_Init();
/* USER CODE BEGIN 2 */
set_sine(dac_data1, NUM_DAC_POINTS) //Set a max amplitude uniformly over number of points, dac_data is initialized as uint8_t dac_data1[NUM_DAC_POINTS];
HAL_TIM_Base_Start(&htim15); //Start the timer for DAC DMA Transfer
HAL_DAC_Init(&hdac1);
(HAL_DAC_Start_DMA(&hdac1, DAC_CHANNEL_2, (uint32_t *)dac_data1, NUM_DAC_POINTS, DAC_ALIGN_8B_R);
}
This setup does not work, but just by initialzing dac_data1 as const uint8_t and predefining it, the DMA works.

Answer 1

Ok, Thanks to Tom V for the insight on the Different Memory Banks. In my case, dac_data1 is placed on RAM, also known as DTCMRAM on the reference manual. DTCMRAM is not accessible to DMA but is chosen to be the default memory location for runtime operations on the H7. A modification in the linker files (In my case, both ..._FLASH.ld and ..._RAM.ld) were needed. I changed the .bss, .data and ._user_heap_stack memory location from RAM to RAM_D1. This was taken directly from: https://community.st.com/s/article/FAQ-DMA-is-not-working-on-STM32H7-devices