stm32f429标准库sdram例程

以下是基于STM32F429标准库的SDRAM例程：

#include "stm32f4xx.h"
#include "stm32f429i_discovery_sdram.h"

#define SDRAM_TIMEOUT       ((uint32_t)0xFFFF)

int main(void)
{
    /* Enable GPIOC, GPIOD, GPIOE, GPIOF, GPIOG and AFIO clocks */
    RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOC | RCC_AHB1Periph_GPIOD | RCC_AHB1Periph_GPIOE | RCC_AHB1Periph_GPIOF | RCC_AHB1Periph_GPIOG, ENABLE);
    RCC_APB2PeriphClockCmd(RCC_APB2Periph_SYSCFG, ENABLE);

    /* Initialize SDRAM */
    SDRAM_Init();

    /* Write data to SDRAM */
    SDRAM_WriteData(0xC0000000, 0x12345678);

    /* Read data from SDRAM */
    uint32_t data = SDRAM_ReadData(0xC0000000);

    while (1);
}

void SDRAM_Init(void)
{
    GPIO_InitTypeDef GPIO_InitStructure;

    /* Enable FMC clock */
    RCC_AHB3PeriphClockCmd(RCC_AHB3Periph_FMC, ENABLE);

    /* Configure SDNE1 and SDCKE1 pins */
    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_5 | GPIO_Pin_6;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;
    GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
    GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL;
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_100MHz;
    GPIO_Init(GPIOC, &GPIO_InitStructure);
    GPIO_PinAFConfig(GPIOC, GPIO_PinSource5, GPIO_AF_FMC);
    GPIO_PinAFConfig(GPIOC, GPIO_PinSource6, GPIO_AF_FMC);

    /* Configure A0-A3 pins */
    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_0 | GPIO_Pin_1 | GPIO_Pin_2 | GPIO_Pin_3;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;
    GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
    GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL;
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_100MHz;
    GPIO_Init(GPIOD, &GPIO_InitStructure);
    GPIO_PinAFConfig(GPIOD, GPIO_PinSource0, GPIO_AF_FMC);
    GPIO_PinAFConfig(GPIOD, GPIO_PinSource1, GPIO_AF_FMC);
    GPIO_PinAFConfig(GPIOD, GPIO_PinSource2, GPIO_AF_FMC);
    GPIO_PinAFConfig(GPIOD, GPIO_PinSource3, GPIO_AF_FMC);

    /* Configure D0-D3 pins */
    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_14 | GPIO_Pin_15 | GPIO_Pin_0 | GPIO_Pin_1;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;
    GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
    GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL;
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_100MHz;
    GPIO_Init(GPIOE, &GPIO_InitStructure);
    GPIO_PinAFConfig(GPIOE, GPIO_PinSource14, GPIO_AF_FMC);
    GPIO_PinAFConfig(GPIOE, GPIO_PinSource15, GPIO_AF_FMC);
    GPIO_PinAFConfig(GPIOE, GPIO_PinSource0, GPIO_AF_FMC);
    GPIO_PinAFConfig(GPIOE, GPIO_PinSource1, GPIO_AF_FMC);

    /* Configure D4-D11 pins */
    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_7 | GPIO_Pin_8 | GPIO_Pin_9 | GPIO_Pin_10 | GPIO_Pin_11 | GPIO_Pin_12 | GPIO_Pin_13 | GPIO_Pin_14;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;
    GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
    GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL;
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_100MHz;
    GPIO_Init(GPIOF, &GPIO_InitStructure);
    GPIO_PinAFConfig(GPIOF, GPIO_PinSource7, GPIO_AF_FMC);
    GPIO_PinAFConfig(GPIOF, GPIO_PinSource8, GPIO_AF_FMC);
    GPIO_PinAFConfig(GPIOF, GPIO_PinSource9, GPIO_AF_FMC);
    GPIO_PinAFConfig(GPIOF, GPIO_PinSource10, GPIO_AF_FMC);
    GPIO_PinAFConfig(GPIOF, GPIO_PinSource11, GPIO_AF_FMC);
    GPIO_PinAFConfig(GPIOF, GPIO_PinSource12, GPIO_AF_FMC);
    GPIO_PinAFConfig(GPIOF, GPIO_PinSource13, GPIO_AF_FMC);
    GPIO_PinAFConfig(GPIOF, GPIO_PinSource14, GPIO_AF_FMC);

    /* Configure D12-D15 pins */
    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_0 | GPIO_Pin_1 | GPIO_Pin_2 | GPIO_Pin_3;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;
    GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
    GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL;
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_100MHz;
    GPIO_Init(GPIOG, &GPIO_InitStructure);
    GPIO_PinAFConfig(GPIOG, GPIO_PinSource0, GPIO_AF_FMC);
    GPIO_PinAFConfig(GPIOG, GPIO_PinSource1, GPIO_AF_FMC);
    GPIO_PinAFConfig(GPIOG, GPIO_PinSource2, GPIO_AF_FMC);
    GPIO_PinAFConfig(GPIOG, GPIO_PinSource3, GPIO_AF_FMC);

    /* SDRAM initialization sequence */
    FMC_SDRAMTimingInitTypeDef SDRAM_Timing_InitStructure;
    FMC_SDRAMInitTypeDef SDRAM_InitStructure;

    SDRAM_Timing_InitStructure.FMC_LoadToActiveDelay = 2;
    SDRAM_Timing_InitStructure.FMC_ExitSelfRefreshDelay = 7;
    SDRAM_Timing_InitStructure.FMC_SelfRefreshTime = 4;
    SDRAM_Timing_InitStructure.FMC_RowCycleDelay = 7;
    SDRAM_Timing_InitStructure.FMC_WriteRecoveryTime = 2;
    SDRAM_Timing_InitStructure.FMC_RPDelay = 2;
    SDRAM_Timing_InitStructure.FMC_RCDDelay = 2;

    SDRAM_InitStructure.FMC_Bank = FMC_Bank2_SDRAM;
    SDRAM_InitStructure.FMC_ColumnBitsNumber = FMC_ColumnBits_Number_8b;
    SDRAM_InitStructure.FMC_RowBitsNumber = FMC_RowBits_Number_12b;
    SDRAM_InitStructure.FMC_SDMemoryDataWidth = FMC_SDMemory_Width_16b;
    SDRAM_InitStructure.FMC_InternalBankNumber = FMC_InternalBank_Number_4;
    SDRAM_InitStructure.FMC_CASLatency = FMC_CAS_Latency_2;
    SDRAM_InitStructure.FMC_WriteProtection = FMC_Write_Protection_Disable;
    SDRAM_InitStructure.FMC_SDClockPeriod = FMC_SDClock_Period_2;
    SDRAM_InitStructure.FMC_ReadBurst = FMC_Read_Burst_Disable;
    SDRAM_InitStructure.FMC_ReadPipeDelay = FMC_ReadPipe_Delay_1;
    SDRAM_InitStructure.FMC_SDRAMTimingStruct = &SDRAM_Timing_InitStructure;

    FMC_SDRAMInit(&SDRAM_InitStructure);

    /* SDRAM bank enable */
    FMC_SDRAMCmdConfigTypeDef SDRAM_Cmd_InitStructure;

    SDRAM_Cmd_InitStructure.FMC_CommandMode = FMC_Command_Mode_CLK_Enabled;
    SDRAM_Cmd_InitStructure.FMC_CommandTarget = FMC_Command_Target_bank2;
    SDRAM_Cmd_InitStructure.FMC_AutoRefreshNumber = 1;
    SDRAM_Cmd_InitStructure.FMC_ModeRegisterDefinition = 0;
    FMC_SDRAMCmdConfig(&SDRAM_Cmd_InitStructure);

    /* Wait for SDRAM initialization */
    uint32_t timeout = SDRAM_TIMEOUT;
    while (FMC_GetFlagStatus(FMC_Bank2_SDRAM, FMC_FLAG_BUSY) != RESET)
    {
        if (timeout-- == 0)
        {
            /* SDRAM initialization error */
            while (1);
        }
    }
}

void SDRAM_WriteData(uint32_t addr, uint32_t data)
{
    /* Write data to SDRAM */
    *(uint32_t *)addr = data;
}

uint32_t SDRAM_ReadData(uint32_t addr)
{
    /* Read data from SDRAM */
    return *(uint32_t *)addr;
}

这个例程用到了SDRAM外设，需要连接到MCU的外部引脚。具体的SDRAM引脚分配可以在STM32F429I Discovery板手册中找到。在本例程中，SDRAM连接到了MCU的Bank2，使用16位数据总线，12位行地址和8位列地址。在初始化SDRAM时，需要设置SDRAM的时序参数。在写入和读取数据时，需要将SDRAM地址转换为指针，并使用指针进行数据传输。