技术咨询
代买器件
商务客服
研发客服此篇限定研究范围为FLASH区域的访问规则。
以下结论均为实测所得：
一、读
1.单字节读例程，单字节读可以从任意地址开始读
uint8_t STMFLASH_ReadByte(uint32_t faddr)
{
return *(volatile uint8_t*)faddr;
}
2.半字（2个字节）读例程， 半字读只能从偶数地址开始读 ，从奇数地址读的话单片机就死机了
uint16_t STMFLASH_ReadHalfWord(uint32_t faddr)
{
return *(volatile uint16_t*)faddr;
}
3.字（4个字节）读例程， 按字读只能从4的整数倍地址开始读 ，否则单片机死机
uint32_t STMFLASH_ReadWord(uint32_t faddr)
{
return *(volatile uint32_t*)faddr;
}
二、写
1.单次写入字节数：
我看G0x1的技术参考手册上说一次写入是72bit（64bit加ecc），我实际测试是单次写入只能是32bit，以实际测试为准
（1）单字节写，写不了，单片机死机
我在HAL库里面把库函数FLASH_Program_DoubleWord改成如下进行验证的
``
static void FLASH_Program_DoubleWord(uint32_t Address, uint64_t Data)
{
/* Set PG bit */
SET_BIT(FLASH->CR, FLASH_CR_PG);
*(uint8_t *)Address = (uint8_t)(Data&0xff);__ISB();
*((uint8_t *)Address+1) = (uint8_t)((Data>>8U)&0xff);__ISB();
*((uint8_t *)Address+2) = (uint8_t)((Data>>16U)&0xff);__ISB();
*((uint8_t *)Address+3) = (uint8_t)((Data>>24U)&0xff);__ISB();
*((uint8_t *)Address+4) = (uint8_t)((Data>>32U)&0xff);__ISB();
*((uint8_t *)Address+5) = (uint8_t)((Data>>40U)&0xff);__ISB();
*((uint8_t *)Address+6) = (uint8_t)((Data>>48U)&0xff);__ISB();
*((uint8_t *)Address+7) = (uint8_t)((Data>>56U)&0xff);
}
``
（2）**半字写，写不了，单片机死机
我在HAL库里面把库函数FLASH_Program_DoubleWord改成如下进行验证的
static void FLASH_Program_DoubleWord(uint32_t Address, uint64_t Data)
{
/* Set PG bit */
SET_BIT(FLASH->CR, FLASH_CR_PG);
*(uint16_t *)Address = (uint16_t)(Data&0xffff);__ISB();
*((uint16_t *)Address+2) = (uint16_t)((Data>>16U)&0xffff);__ISB();
*((uint16_t *)Address+4) = (uint16_t)((Data>>32U)&0xffff);__ISB();
*((uint16_t *)Address+6) = (uint16_t)((Data>>48U)&0xffff);
}
（3）按字写(4个字节，32bit)，可以，HAL库函数FLASH_Program_DoubleWord里面就是按字写的
static void FLASH_Program_DoubleWord(uint32_t Address, uint64_t Data)
{
/* Set PG bit */
SET_BIT(FLASH->CR, FLASH_CR_PG);
/* Program first word */
*(uint32_t *)Address = (uint32_t)Data;
/* Barrier to ensure programming is performed in 2 steps, in right order
(independently of compiler optimization behavior) */
__ISB();
/* Program second word */
*(uint32_t *)(Address + 4U) = (uint32_t)(Data >> 32U);
}
（4） 按64bit写， 写不了，单片机死机
我在HAL库里面把库函数FLASH_Program_DoubleWord改成如下进行验证的
static void FLASH_Program_DoubleWord(uint32_t Address, uint64_t Data)
{
/* Set PG bit */
SET_BIT(FLASH->CR, FLASH_CR_PG);
*(uint64_t *)Address = (uint64_t)Data;
}
2.写入的首地址规则
经过实际验证得出：**写入首地址必须为8的整数倍，不然就会发生错误：如果为4的整数倍但不是8的整数倍，单片机不会死机，但是写入的值全部变成0x3F，其他既不是4的整数倍也不是8的整数倍的地址，单片机会死机。
按以下代码改变写入首地址即可进行验证
STMFLASH_Write(FLASH_CALIBRATION_ADDR+8,String,sizeof(String));
HAL_Delay(10);
STMFLASH_Read(FLASH_CALIBRATION_ADDR,buffer,sizeof(String)/4+1);
HAL_Delay(10);
Uart_Send_Data(buffer, sizeof(String));