为什么我的闪存控制寄存器在我写入时没有更新（STM32）？

Question

我正在尝试写来更新我在 STM32G0 上的工程字节，但我遇到了困难。我需要通过写入 FLASH_KEYR 寄存器来解锁闪存。手册是这样说的：

After reset, write into the FLASH control register (FLASH_CR) is not allowed so as to protect the Flash memory against possible unwanted operations due, for example, to electric disturbances. The following sequence unlocks these registers:

1. Write KEY1 = 0x4567 0123 in the FLASH key register (FLASH_KEYR)
2. Write KEY2 = 0xCDEF 89AB in the FLASH key register (FLASH_KEYR).

Any wrong sequence will lock the FLASH_CR registers until the next system reset. In the case of a wrong key sequence, a bus error is detected and a Hard Fault interrupt is generated.
The FLASH_CR registers can be locked again by software by setting the LOCK bit in one of these registers.

Note: The FLASH_CR register cannot be written when the BSY1 bit of the FLASH status register (FLASH_SR) is set. Any attempt to write to this register with the BSY1 bit set causes the AHB bus to stall until the BSY1 bit is cleared.

我确保在尝试写入时我的 BSY1 位是清晰的，我相信这是唯一的条件。

这就是我的写作方式：

#define KEY1  0x45670123
#define KEY2  0xCDEF89AB

... 

FLASH->KEYR = KEY1;
FLASH->KEYR = KEY2;

此时，我的 FLASH_KEYR 寄存器仍然是 0x0。有谁知道为什么？

编辑：这是我的代码

        #define TEST_FLASH_BYTES    ((uint32_t)0x0801FF00)

        ...

        FLASH->CR &= FLASH_CR_LOCK;
        FLASH->KEYR = KEY1;
        FLASH->KEYR = KEY2;

        while(__HAL_FLASH_GET_FLAG(FLASH_SR_BSY1) != 0) {}

        program_flash(TEST_FLASH_BYTES, 0x1234567887654321);

        while (__HAL_FLASH_GET_FLAG(FLASH_SR_BSY1) != 0) {}

        FLASH->SR &= FLASH_SR_EOP;
        FLASH->CR &= FLASH_CR_PG;

这里是program_flash：

static void program_flash(uint32_t address, uint64_t data)
{
    *(uint32_t *)address = (uint32_t)data;

    (independently of compiler optimization behavior) */
    __ISB();

    *(uint32_t *)(address + 4U) = (uint32_t)(data >> 32U);
}

编辑：它是一个只写寄存器，所以我无法读回它。我想出了如何成功写入内存。

Answer 1

此代码使 boot0 引脚能够像传统 stm32 芯片一样工作。

    //enable BOOT0 pin
    while(GET32(0x40022010)&0x10000) continue;
    PUT32(0x40022008,0x45670123);
    PUT32(0x40022008,0xCDEF89AB);
    PUT32(0x4002200C,0x08192A3B);
    PUT32(0x4002200C,0x4C5D6E7F);
//from the manual:
//ST production value: 0xDFFF E1AA
    PUT32(0x40022020,0xDEFFE1AA);
    while(GET32(0x40022010)&0x10000) continue;
    PUT32(0x40022014,0x00020000);
    while(GET32(0x40022010)&0x10000) continue;

PUT32 执行 str 指令，GET32 执行 ldr 指令。

不同的STM32G0对其中一些寄存器有不同的默认值，我现在为FLASH_CR寄存器打开的是：

Reset value: 0xC000 0000

这是两个锁定位，因此上面的每个解锁序列都绑定到一个位，因此两个序列也是如此，理论上两个位都解锁。可以挖出一块板/芯片并尝试这个并编辑这个答案以确认。

看起来您是从程序中执行此操作的，这些芯片非常挑剔，擦除闪存（如在新芯片中）后，您可以使用引导加载程序进行加载，一旦有东西，您就可以通过 SWD 进入（我假设有一种方法可以阻止它），但是你不能使用 swd 来编写这些寄存器来执行这些你必须运行代码的任务，你可以从 ram 或 flash 运行它。

根据您要更改的内容，您可能需要重启芯片才能看到更改生效。

编辑

while(GET32(0x40022010)&0x10000) continue; //need this here?
ra=GET32(0x40022014); //FLASH_CR
while(GET32(0x40022010)&0x10000) continue;
PUT32(0x40022008,0x45670123);
PUT32(0x40022008,0xCDEF89AB);
rb=GET32(0x40022014); //FLASH_CR
PUT32(0x4002200C,0x08192A3B);
PUT32(0x4002200C,0x4C5D6E7F);
rc=GET32(0x40022014); //FLASH_CR
hexstring(ra);
hexstring(rb);
hexstring(rc);

串口输出

C0000000 
40000000 
00000000 

正如文档中所预期的那样。

您如何以及何时阅读注册表？您是否在解锁和读取之间触摸任何寄存器？

Answer 2

我猜你没有启用数字 FLASH 接口。

RCC -> AHBENR |= RCC_AHBENR_FLASHEN;

然后

等待 FLASH 外设

while (FLASH -> SR & FLASH_SR_BSY1) ;

        RCC -> AHBENR |= RCC_AHBENR_FLASHEN;
        (*void)RCC -> AHBENR; // readback instead of delay to let this change to propagate throut the bus.
        while(FLASH -> SR & FLASH_SR_BSY1));
        //FLASH->CR &= FLASH_CR_LOCK; this line is worng. First of all it is not the way of reseting the bits, Secondly this bit is SET ONLY which meand that you can set it to enable the lock again
        FLASH->KEYR = KEY1;
        FLASH->KEYR = KEY2;

        while(FLASH -> SR & FLASH_SR_BSY1));