STM32F469BIT6外接IS42S16400J SDRAM读写数据异常求助

定制PCB使用STM32F469BIT6芯片，外接IS42S16400J-7TLI型8Mb SDRAM。此前基于STM32F429ZIT6搭配同款SDRAM（选型参考STM32F429-DISCO开发板）的板卡可正常读写SDRAM，但更换为STM32F469BIT6后，虽能执行读写操作，但数据出现损坏。

测试代码 #

/* USER CODE BEGIN PV */
volatile uint8_t *externalRAM = (uint8_t*) 0xC0000000;
const uint32_t size = 8 * 1024 * 1024; //8MB
/* USER CODE END PV */
/* USER CODE BEGIN 2 */
//write external RAM
for (uint32_t i = 0; i < size; i++) {
    externalRAM[i] = i % 256;
}

//read external RAM
for (uint32_t i = 0; i < size; i++) {
    if (externalRAM[i] != i % 256) {
        asm("nop");
        // insert error handling logic here
    }
}
/* USER CODE END 2 */

SDRAM配置代码 #

/* USER CODE BEGIN FMC_Init 2 */
FMC_SDRAM_CommandTypeDef Command;
/* Step 1 and Step 2 already done in HAL_SDRAM_Init() */
/* Step 3: Configure a clock configuration enable command */
Command.CommandMode = FMC_SDRAM_CMD_CLK_ENABLE; /* Set MODE bits to "001" */
Command.CommandTarget = FMC_SDRAM_CMD_TARGET_BANK2; /* configure the Target Bank bits */
Command.AutoRefreshNumber = 1;
Command.ModeRegisterDefinition = 0;
HAL_SDRAM_SendCommand(&hsdram2, &Command, 0xfff);
HAL_Delay(1); /* Step 4: Insert 100 us minimum delay - Min HAL Delay is 1ms */
/* Step 5: Configure a PALL (precharge all) command */
Command.CommandMode = FMC_SDRAM_CMD_PALL; /* Set MODE bits to "010" */
HAL_SDRAM_SendCommand(&hsdram2, &Command, 0xfff);
/* Step 6: Configure an Auto Refresh command */
Command.CommandMode = FMC_SDRAM_CMD_AUTOREFRESH_MODE; /* Set MODE bits to "011" */
Command.AutoRefreshNumber = 2;
HAL_SDRAM_SendCommand(&hsdram2, &Command, 0xfff);
/* Step 7: Program the external memory mode register */
Command.CommandMode = FMC_SDRAM_CMD_LOAD_MODE;/*set the MODE bits to "100" */
Command.ModeRegisterDefinition = (uint32_t) 0 | 0 << 3 | 2 << 4 | 0 << 7
        | 1 << 9;
HAL_SDRAM_SendCommand(&hsdram2, &Command, 0xfff);
/* Step 8: Set the refresh rate counter - refer to section SDRAM refresh timer register in RM0455 */
/* Set the device refresh rate
 * COUNT = [(SDRAM self refresh time / number of row) x  SDRAM CLK] – 20
 = [(64ms/4096) * 100MHz] - 20 = 1562.5 - 20 ~ 1542 */
HAL_SDRAM_ProgramRefreshRate(&hsdram2, 1292); // 84MHZ
/* USER CODE END FMC_Init 2 */

异常现象 #

示波器可观测到时钟信号，但不同数据类型测试均出现异常：

• 以uint8_t类型写入时，奇数数值会覆盖所有地址，偶数数值仅覆盖偶数地址；
• 以uint16_t类型写入时，仅偶数地址变化且值均相同；
• 以uint32_t类型写入时，内存无任何变化。

已尝试调整时钟频率（30MHz、90MHz）及SDRAM时序参数，问题未解决，寻求技术排查帮助，必要时可提供逻辑分析仪数据。

内容的提问来源于stack exchange，提问作者cserp