ARM编程中Flash ROM驱动示例

Intel Flash芯片 i28f160,i28f320:

i28F320B: 64*64K,64个blocks,4M空间,每个block 64K,第一个64K由8个8*8K小blocks组成.

每个Black可以被独立擦写(寿命周期) 100,000次以上

Flash操作的大概步骤:

flash读写操作中,读应该很简单,和RAM一样,写就复杂一点. 
Intel TE28F320C3的flash是4M空间
flash空间,划分成许多的block,Intel TE28F320C3的flash是4M空间,64个block,每个block由64K.
要对所有的block单独进行操作, 每个操作结束,都需要判断状态, 
每个block操作的大概步骤如下: 
1.unlock 
2.erase 
3.check empty 
所有的block完成上述操作,且状态正确,才能进行下一步,写 
4.write 

arm汇编程序

     LDR r2, =FlashBase                     ;Flash起始地址

//第一步,UNLOCK的64个block,步骤和上边一样

          MOV r1,#63                       ;63x64k block 计数 

01     LDRB   r3, =X16_FLASH_COMMAND_CONFIG_SETUP

          STRB          r3, [r2]           ;该block的首地址  

          LDRB          r3, =X16_FLASH_COMMAND_UNLOCK_BLOCK

          STRB          r3, [r2]           ;将Unlock命令写入

          ADD r2, r2, #0x10000             ;64K
          SUBS          r1, r1, #1
          BNE %b01                            
;Unlock OK                                 ;Unlock 完成

//第二布,擦除blocks

        LDR         r0, =FlashBase
        LDR         r1,=63                       ;擦除 63x64k block
01    LDR     r3, =X16_FLASH_COMMAND_ERASE
        LDR     r2, =X16_FLASH_COMMAND_CONFIRM   
        ORR         r3, r3, r2, LSL #16
        STR         r3, [r0]
        LDR     r3, =X16_FLASH_COMMAND_STATUS ;检查寄存器状态
        STRB    r3, [r0]
02    LDRB    r3, [r0]                              ;读状态
        TST         r3, #X16_FLASH_STATUS_READY 
        BEQ     %b02                          ;若状态ready,执行下一个   
        TST     r3, #X16_FLASH_STATUS_ERROR
        BNE     error_erase_block
        ADD         r0, r0, #0x10000
        SUBS    r1, r1, #1
        BNE         %b01
        B         EraseOK
error_erase_block
..............
;EraseOK                               ;擦除完成

//第三步,检查flash是否为空

;Check Flash Empty
        LDR         r4, =FlashBase
        LDR         r5, =0x100000                    ;检查 1MB
        LDR         r0, =0xffffffff
loop_1
        LDR         r1, [r4]
        CMP         r1, r0                     ;比较地址内容和0xffffffff
        BNE         empty_error
       ADD         r4, r4, #4
        CMP         r4, r5
        BLO         loop_1
        B         CheckOK
empty_error
.................
CheckOK
.................

;Check empty OK                        ;检查完成  

//第四步,写flash

;Burn data to Flash ROM

        LDR         r6, =Length_Flash           ;定义数据长度
        LDR         r0, =FlashBase
        LDR         r1, =BufferBase
        MOV         r9, #0
        LDR         r4,=0x10000000
        LDR         r7,=0xc0001000
        STR         r4,    [r7]
        LDR         r1, [r1, r9]

03    LDR     r3, =X16_FLASH_COMMAND_WRITE
        STRB    r3, [r0]                                         ;把写命令放入Block首地址
       LDR     r3, =X16_FLASH_COMMAND_STATUS   
        LDR         r2, [r7]                                          
        LDR         r5, =0x0000ffff            
        AND         r2, r2, r5
        ORR         r2, r2, r3, LSL #16
        STR         r2, [r0]        
02    LDR         r3, [r0]                                 ;读状态寄存器状态
        TST         r3, #X16_FLASH_STATUS_READY   
        BEQ     %b02                          ;若状态ready,执行下一个

        LDR     r3, =X16_FLASH_COMMAND_WRITE
        LDR         r2, [r7]            
        LDR         r5, =0xffff0000                             ;
        AND         r2, r2, r5
        ORR         r3, r3, r2
        STR         r3, [r0]

        LDR     r3, =X16_FLASH_COMMAND_STATUS
        STRB    r3, [r0]            
02    LDR         r3, [r0]                             ; read status
        TST         r3, #X16_FLASH_STATUS_READY
        BEQ     %b02

        LDR     r4, =X16_FLASH_COMMAND_READ
        STRB    r4, [r0]
        ADD         r0, r0, #4
        LDR         r8, [r7]
        ADD         r8, r8,#1
        STR         r8, [r7]
        ADD         r8, r8, #4
writenext

        SUBS     r6, r6, #4         ;if no finished goto 03
        BHI         %b03
        TST     r3, #X16_FLASH_STATUS_ERROR
        BNE     error_write
        LDR     r3, =X16_FLASH_COMMAND_READ
        STRB    r3, [r0]
        B         BurnOK
error_write
    ..........
BurnOK