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Disable UART2 DMA when using DSHOT to avoid DMA conflict #1538

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Merged
tobbeanton merged 1 commit into from
Oct 8, 2025
Merged

Disable UART2 DMA when using DSHOT to avoid DMA conflict #1538

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12 changes: 12 additions & 0 deletions src/drivers/src/uart2.c
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Original file line number Diff line number Diff line change
Expand Up @@ -52,16 +52,19 @@ static StaticSemaphore_t waitUntilSendDoneBuffer;

static bool isInit = false;

#ifndef CONFIG_MOTORS_ESC_PROTOCOL_DSHOT
static DMA_InitTypeDef DMA_InitStructureShare;
static uint8_t dmaBuffer[UART2_DMA_BUFFER_SIZE];
static bool isUartDmaInitialized;
static uint32_t initialDMACount;
#endif

static StreamBufferHandle_t rxStream;
static EventGroupHandle_t isrEvents;

static bool hasOverrun = false;

#ifndef CONFIG_MOTORS_ESC_PROTOCOL_DSHOT
/**
* Configures the UART DMA. Mainly used for FreeRTOS trace
* data transfer.
Expand Down Expand Up @@ -97,6 +100,7 @@ static void uart2DmaInit(void)

isUartDmaInitialized = true;
}
#endif

void uart2Init(const uint32_t baudrate)
{
Expand Down Expand Up @@ -139,7 +143,10 @@ void uart2Init(const uint32_t baudrate)
USART_InitStructure.USART_HardwareFlowControl = USART_HardwareFlowControl_None;
USART_Init(UART2_TYPE, &USART_InitStructure);

// Only initialize DMA when NOT using DSHOT (DSHOT motors conflict with UART2 DMA)
#ifndef CONFIG_MOTORS_ESC_PROTOCOL_DSHOT
uart2DmaInit();
#endif

// Configure Rx buffer not empty interrupt
NVIC_InitStructure.NVIC_IRQChannel = UART2_IRQ;
Expand Down Expand Up @@ -195,6 +202,10 @@ void uart2SendData(uint32_t size, uint8_t* data)

void uart2SendDataDmaBlocking(uint32_t size, uint8_t* data)
{
#ifdef CONFIG_MOTORS_ESC_PROTOCOL_DSHOT
// DMA disabled due to conflict with brushless motors, fall back to regular send
uart2SendData(size, data);
#else
if (isUartDmaInitialized)
{
xSemaphoreTake(uartBusy, portMAX_DELAY);
Expand All @@ -217,6 +228,7 @@ void uart2SendDataDmaBlocking(uint32_t size, uint8_t* data)
xSemaphoreTake(waitUntilSendDone, portMAX_DELAY);
xSemaphoreGive(uartBusy);
}
#endif
}

int uart2Putchar(int ch)
Expand Down