DMA MCAL Module

Supported STM32 families: F4 · G4
Not supported: H5, H7, L4, U5

MCAL Driver (Dma_Lib)

The DMA module provides a complete MCAL-level abstraction for configuring, controlling, and monitoring STM32 DMA peripherals. It supports full control of DMA/DMAMUX routing, transfer modes, interrupts, and channel-level configuration.

---

🧩 Architecture Overview

Dma_Lib
 ├── Dma_Port.h
 ├── Dma_Types.h
 ├── Dma.c / Dma.h
 └── Config/

Only Dma_Port.h shall be used by application code.

---

🔄 DMA → DMAMUX → PERIPH Architecture

 +----------------------+
 |   Peripheral (e.g.) |
 |  USART, SPI, ADC... |
 +----------+-----------+
            |
            | DMA Request (ID)
            v
   +--------+---------+
   |     DMAMUX       |
   |------------------|
   | Request Routing  |
   | Channel Mapping  |
   +--------+---------+
            |
            | Routed DMA Request
            v
   +--------+---------+
   |       DMA        |
   |------------------|
   | Channel Control  |
   | Transfer Config  |
   | Interrupt Logic  |
   +------------------+

---

🚀 Features

• DMA1/DMA2 support
• Memory⇄Peripheral / Memory⇄Memory transfers
• Normal & Circular modes
• 8/16/32-bit transfer sizes
• Peripheral & memory address increments
• Priority levels
• Full interrupt system with user callbacks
• DMAMUX request routing

---

📦 Public API Summary

Full API available in Dma_Port.h.

Includes:

• Initialization / default configuration
• Transfer start/stop
• Channel activation
• Direction / mode / increments
• Peripheral & memory addresses
• Data count
• Priority
• Peripheral request selection
• Interrupt enabling/disabling
• Callback registration

---

⚙️ Configuration Structure

typedef struct
{
    dma_PeriphId_t           DmaPeriphId;
    dma_ChannelId_t          DmaChannel;
    dma_Direction_t          Direction;
    dma_TransferMode_t       TransferMode;
    dma_PeriphAddr_t         PeriphAddress;
    dma_MemoryAddr_t         MemoryAddress;
    dma_PeriphAddrInc_t      PeriphAddrIncrement;
    dma_MemoryAddrInc_t      MemoryAddrIncrement;
    dma_PeriphTransferSize_t PeriphTransferSize;
    dma_MemoryTransferSize_t MemoryTransferSize;
    dma_DataCount_t          DataCount;
    dma_PeriphReqId_t        PeripheralReqId;
    dma_Priority_t           Priority;
    dma_IsrCallback          TransferCompleteCallback;
    dma_IsrCallback          HalfTransferCallback;
    dma_IsrCallback          TransferErrorCallback;
} dma_ConfigStruct_t;

---

🧪 Example Initialization

Example 1 — USART1 TX DMA

dma_ConfigStruct_t cfg;
Dma_Get_DefaultConfig(&cfg);

cfg.DmaPeriphId          = DMA_PERIPH_1;
cfg.DmaChannel           = DMA_CHANNEL_4;
cfg.Direction            = DMA_DIR_MEMORY_TO_PERIPH;
cfg.TransferMode         = DMA_TRANSFER_MODE_NORMAL;
cfg.PeriphAddress        = (uint32_t)&USART1->TDR;
cfg.MemoryAddress        = (uint32_t)txBuffer;
cfg.PeriphAddrIncrement  = DMA_PERIPH_ADDR_STATIC;
cfg.MemoryAddrIncrement  = DMA_MEMORY_ADDR_INCREMENT;
cfg.PeriphTransferSize   = DMA_PERIPH_TRANSFER_SIZE_BYTE;
cfg.MemoryTransferSize   = DMA_MEMORY_TRANSFER_SIZE_BYTE;
cfg.DataCount            = TX_LEN;
cfg.PeripheralReqId      = DMA_REQ_USART1_TX;
cfg.Priority             = DMA_PRIORITY_HIGH;

cfg.TransferCompleteCallback = TxDone;
cfg.TransferErrorCallback    = TxError;

Dma_Init(&cfg);

---

Example 2 — Memory to Memory

dma_ConfigStruct_t cfg;
Dma_Get_DefaultConfig(&cfg);

cfg.DmaPeriphId     = DMA_PERIPH_1;
cfg.DmaChannel      = DMA_CHANNEL_1;
cfg.Direction       = DMA_DIR_MEMORY_TO_MEMORY;
cfg.TransferMode    = DMA_TRANSFER_MODE_NORMAL;
cfg.PeriphAddress   = (uint32_t)src;
cfg.MemoryAddress   = (uint32_t)dst;
cfg.DataCount       = 256;
cfg.PeripheralReqId = DMA_REQ_MEM2MEM;

Dma_Init(&cfg);

---

🚀 Advanced Examples

🔵 Example A: Double Buffer Mode (Ping-Pong RAM Transfer)

Double-buffer mode allows DMA to alternate between Buffer A and Buffer B
automatically without stopping transfers. This is ideal for:

• Audio processing
• Signal filtering
• Real-time data capture
• Zero-copy streaming

🧠 How it works:

• DMA loads data to BufferA
• When half-transfer interrupt fires → CPU processes BufferA while DMA writes BufferB
• When transfer-complete event fires → CPU processes BufferB while DMA writes BufferA

Example:

uint16_t BufferA[128];
uint16_t BufferB[128];

void SetupDmaDoubleBuffer(void)
{
    dma_ConfigStruct_t cfg;
    Dma_Get_DefaultConfig(&cfg);

    cfg.DmaPeriphId     = DMA_PERIPH_1;
    cfg.DmaChannel      = DMA_CHANNEL_2;
    cfg.Direction       = DMA_DIR_PERIPH_TO_MEMORY;
    cfg.TransferMode    = DMA_TRANSFER_MODE_CIRCULAR;
    cfg.PeriphAddress   = (uint32_t)&ADC1->DR;
    cfg.MemoryAddress   = (uint32_t)BufferA;
    cfg.DataCount       = 128;
    cfg.PeripheralReqId = DMA_REQ_ADC1;
    cfg.Priority        = DMA_PRIORITY_HIGH;

    cfg.HalfTransferCallback    = ProcessBufferA;   // Called for Buffer A
    cfg.TransferCompleteCallback = ProcessBufferB;  // Called for Buffer B

    Dma_Init(&cfg);

    // Switch secondary buffer
    LL_DMA_SetMemory2Address(DMA1, LL_DMA_CHANNEL_2, (uint32_t)BufferB);
}

🧩 Use cases:

Use case	Why double-buffer helps
Audio codec input	Continuous PCM capture
Sensor streaming	Ensures no samples are lost
PWM feedback sampling	Deterministic acquisition
Real-time DSP	Ping-pong buffers eliminate copy delays

---

🟢 Example B: Circular ADC Sampling (Continuous Conversion)

Circular DMA mode restarts the transfer automatically once it reaches the end. Best for continuous ADC sampling.

Example:

#define ADC_BUF_SIZE 256
uint16_t AdcBuffer[ADC_BUF_SIZE];

void SetupCircularAdcDma(void)
{
    dma_ConfigStruct_t cfg;
    Dma_Get_DefaultConfig(&cfg);

    cfg.DmaPeriphId       = DMA_PERIPH_1;
    cfg.DmaChannel        = DMA_CHANNEL_1;
    cfg.Direction         = DMA_DIR_PERIPH_TO_MEMORY;
    cfg.TransferMode      = DMA_TRANSFER_MODE_CIRCULAR;
    cfg.PeriphAddress     = (uint32_t)&ADC1->DR;
    cfg.MemoryAddress     = (uint32_t)AdcBuffer;
    cfg.DataCount         = ADC_BUF_SIZE;
    cfg.PeripheralReqId   = DMA_REQ_ADC1;

    cfg.HalfTransferCallback     = OnAdcHalfFilled;
    cfg.TransferCompleteCallback = OnAdcFilled;

    Dma_Init(&cfg);
}

🧩 Use cases:

• Current measurement on SMPS
• Motor control FOC loop
• High-frequency ADC sampling
• Logging sensors without CPU load

---

🟣 Example C: SPI DMA TX/RX Dual-Channel Mode

SPI requires:

• One DMA channel for TX
• One DMA channel for RX

This allows full-duplex DMA transfers.

Example:

uint8_t txData[64];
uint8_t rxData[64];

void SetupSpiDma(void)
{
    dma_ConfigStruct_t txCfg, rxCfg;

    // TX channel
    Dma_Get_DefaultConfig(&txCfg);
    txCfg.DmaPeriphId      = DMA_PERIPH_1;
    txCfg.DmaChannel       = DMA_CHANNEL_3;
    txCfg.Direction        = DMA_DIR_MEMORY_TO_PERIPH;
    txCfg.PeriphAddress    = (uint32_t)&SPI1->DR;
    txCfg.MemoryAddress    = (uint32_t)txData;
    txCfg.DataCount        = sizeof(txData);
    txCfg.PeripheralReqId  = DMA_REQ_SPI1_TX;
    txCfg.TransferCompleteCallback = OnSpiTxDone;

    // RX channel
    Dma_Get_DefaultConfig(&rxCfg);
    rxCfg.DmaPeriphId      = DMA_PERIPH_1;
    rxCfg.DmaChannel       = DMA_CHANNEL_2;
    rxCfg.Direction        = DMA_DIR_PERIPH_TO_MEMORY;
    rxCfg.PeriphAddress    = (uint32_t)&SPI1->DR;
    rxCfg.MemoryAddress    = (uint32_t)rxData;
    rxCfg.DataCount        = sizeof(rxData);
    rxCfg.PeripheralReqId  = DMA_REQ_SPI1_RX;
    rxCfg.TransferCompleteCallback = OnSpiRxDone;

    Dma_Init(&txCfg);
    Dma_Init(&rxCfg);
}

🧩 Use cases:

• SPI screen refresh
• High-speed sensors (IMU, gyroscope)
• Flash memory read/write
• Full-duplex communication (e.g., W5500 Ethernet chip)

---

📐 UML Sequence – DMA Transfer Flow

+---------+       +---------+       +------------+
|  CPU    |       |  DMAMUX |       |    DMA     |
+---------+       +---------+       +------------+
     |                 |                  |
     | Configure DMA   |                  |
     |---------------->|                  |
     |                 | Map Req → Ch     |
     |                 |----------------->|
     |                 |                  |
     | Enable Channel  |                  |
     |----------------------------------->|
     |                 |                  |
     |        Transfer Starts             |
     |<-----------------------------------|
     |                 |                  |
     |   Half Transfer Interrupt (HT)     |
     |<-----------------------------------|
     | Process first half buffer          |
     |----------------------------------->|
     |                 |                  |
     | Transfer Complete Interrupt (TC)   |
     |<-----------------------------------|
     | Process second buffer              |
     |----------------------------------->|
     |                 |                  |

---

🛠 CMake Integration

add_library(Dma_Lib
    Dma_Port.h
    Dma_Types.h
    Dma.c
    Dma.h
)

target_include_directories(Dma_Lib PUBLIC .)

Usage:

target_link_libraries(App PRIVATE Dma_Lib)

---

License

This project is licensed under the Creative Commons Attribution–NonCommercial 4.0 International (CC BY-NC 4.0).

You are free to use, modify, and share this work for non-commercial purposes, provided appropriate credit is given.

See LICENSE.md for full terms or visit creativecommons.org/licenses/by-nc/4.0.

---

Authors

• Mr.Nobody — embedbits.com

Contributions are welcome! Please open a pull request.

---