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.
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