STM32F429驱动外部SDRAM

STM32F429的一个很大优势就是可以直接驱动SDRAM，这样一下子就可以外扩可观的运存，很诱惑。

这里用到的SDRAM 为W9825G6KH, 256Mbit， 32MByte

配置CubeMX

这里不展开这里面的数值的具体计算过程，主要是按照手册来算的，感兴趣的可以网上寻找，有很多相关的资料。

SDRAM 初始化，SDRAM不像SRAM配置好了就可以用，他需要初始化

#include "stm32f4xx_hal.h"

extern SDRAM_HandleTypeDef hsdram1;

#define SDRAM_MODEREG_BURST_LENGTH_1             ((uint16_t)0x0000)

#define SDRAM_MODEREG_BURST_LENGTH_2             ((uint16_t)0x0001)

#define SDRAM_MODEREG_BURST_LENGTH_4             ((uint16_t)0x0002)

#define SDRAM_MODEREG_BURST_LENGTH_8             ((uint16_t)0x0004)

#define SDRAM_MODEREG_BURST_TYPE_SEQUENTIAL      ((uint16_t)0x0000)

#define SDRAM_MODEREG_BURST_TYPE_INTERLEAVED     ((uint16_t)0x0008)

#define SDRAM_MODEREG_CAS_LATENCY_2              ((uint16_t)0x0020)

#define SDRAM_MODEREG_CAS_LATENCY_3              ((uint16_t)0x0030)

#define SDRAM_MODEREG_OPERATING_MODE_STANDARD    ((uint16_t)0x0000)

#define SDRAM_MODEREG_WRITEBURST_MODE_PROGRAMMED ((uint16_t)0x0000)

#define SDRAM_MODEREG_WRITEBURST_MODE_SINGLE     ((uint16_t)0x0200)

#define SDRAM_BANK1_BASE_ADDRESS    0XC0000000  

#define SDRAM_HALF_WORD_SIZE        0x1000000      //0x1000000 - 16M*16bit =32Mbyte

void SDRAM_Initialization_Sequence(SDRAM_HandleTypeDef *hsdram);

void SDRAM_TEST(void);

typedef uint16_t u16;

typedef uint8_t u8;

typedef uint32_t u32;

/**

  * @brief  Perform the SDRAM exernal memory inialization sequence

  * @param  hsdram: SDRAM handle

  * @param  Command: Pointer to SDRAM command structure

  * @retval None

  SDRAM刷新周期是64ms，行数是8192行，时钟频率是180MHz/2=90MHz

    所有COUNT = (64ms/8192)/(1/90us)-20 = 64000*90/8192-20 = 683

  */

void SDRAM_Initialization_Sequence(SDRAM_HandleTypeDef *hsdram)

{

    __IO uint32_t tmpmrd = 0;

    FMC_SDRAM_CommandTypeDef Command;

    /* Configure a clock configuration enable command */

    Command.CommandMode = FMC_SDRAM_CMD_CLK_ENABLE;

    Command.CommandTarget = FMC_SDRAM_CMD_TARGET_BANK1;

    Command.AutoRefreshNumber = 1;

    Command.ModeRegisterDefinition = 0;

    /* Send the command */

    HAL_SDRAM_SendCommand(hsdram, &Command, 0x1000);

    /* Insert 10 ms delay */

    HAL_Delay(10);

    /* Configure a PALL (precharge all) command */

    Command.CommandMode = FMC_SDRAM_CMD_PALL;

    Command.CommandTarget      = FMC_SDRAM_CMD_TARGET_BANK1;

    Command.AutoRefreshNumber = 1;

    Command.ModeRegisterDefinition = 0;

    /* Send the command */

    HAL_SDRAM_SendCommand(hsdram, &Command, 0x1000);

    /* Configure a Auto-Refresh command */

    Command.CommandMode = FMC_SDRAM_CMD_AUTOREFRESH_MODE;

    Command.CommandTarget = FMC_SDRAM_CMD_TARGET_BANK1;

    Command.AutoRefreshNumber = 8;

    Command.ModeRegisterDefinition = 0;

    /* Send the command */

    HAL_SDRAM_SendCommand(hsdram, &Command, 0x1000);

    /* Program the external memory mode register */

    tmpmrd = (uint32_t)SDRAM_MODEREG_BURST_LENGTH_8|

             SDRAM_MODEREG_BURST_TYPE_SEQUENTIAL   |

             SDRAM_MODEREG_CAS_LATENCY_3           |

             SDRAM_MODEREG_OPERATING_MODE_STANDARD |

             SDRAM_MODEREG_WRITEBURST_MODE_SINGLE;

    Command.CommandMode = FMC_SDRAM_CMD_LOAD_MODE;

    Command.CommandTarget = FMC_SDRAM_CMD_TARGET_BANK1;

    Command.AutoRefreshNumber = 1;

    Command.ModeRegisterDefinition = tmpmrd;

    /* Send the command */

    HAL_SDRAM_SendCommand(hsdram, &Command, 0x1000);

    /* Set the refresh rate counter */

    /* (7.81us x Freq) - 20 */

    /* Set the device refresh counter */

    HAL_SDRAM_ProgramRefreshRate(hsdram, 683);

}

void SDRAM_TEST(void)

{

uint32_t temp = 0;

uint16_t err=0;

for(i=0;i {

*(__IO uint16_t*)(SDRAM_BANK1_BASE_ADDRESS+2*i) = (uint16_t)i;

}

for(i=0;i {

temp = 0;

temp = *(__IO uint16_t*)(SDRAM_BANK1_BASE_ADDRESS+2*i);

if(temp!=(uint16_t)i)

{

err++;

}

}

printf("Total error =%dn",err);

}

3.MAIN函数中加入即可

SDRAM_Initialization_Sequence();

SDRAM_TEST();//optioanl