STM32探秘 之FSMC

STM32的FSMC真是一个万能的总线控制器,不仅可以控制SRAM,NOR FLASH,NAND FLASH,PC Card,还能控制LCD,TFT.

一般越是复杂的东西,理解起来就很困难,但是使用上却很方便,如USB.

不过FSMC也有很诡异的地方.如

*(volatile uint16_t *)0x60400000=0x0; 
 // 实际地址A21=1,而非A22.[注:0x60400000=0x60000000|(1UL<<22) ]
*(volatile uint16_t *)0x60800000=0x0; 
// 实际地址A22=1,而非A23	[注:0x60800000=0x60000000|(1UL<<23) ]

为什么呢?那时我还以为软件或硬件还是芯片有BUG,
我就是从上面的不解中开始研究FSMC的…

1.FSMC信号引脚

STM32的管脚排列很没有规律,而且分布在多个不同端口上,初始化要十分小心.需要用到的引脚都要先初始化成"复用功能推挽输出"模式.(GPIO_InitStructure.GPIO_Mode=GPIO_Mode_AF_PP )
并且开启时钟 (RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOx, ENABLE); ) 像STM32F103Z(144脚)芯片有独立的地址和数据总线,而STM32F103V(100脚)就没有, 地址和数据总线要像51单片机一样分时复用,而在STM32F103R系列(64脚)就没有FSMC模块.

复用总线时管脚:
PD14,//FSMC_DA0
PD15,//FSMC_DA1
PD0 ,//FSMC_DA2
PD1 ,//FSMC_DA3
PE7 ,//FSMC_DA4
PE8 ,//FSMC_DA5
PE9 ,//FSMC_DA6
PE10,//FSMC_DA7
PE11,//FSMC_DA8
PE12,//FSMC_DA9
PE13,//FSMC_DA10
PE14,//FSMC_DA11
PE15,//FSMC_DA12
PD8 ,//FSMC_DA13
PD9 ,//FSMC_DA14
PD10,//FSMC_DA15
PD11,//FSMC_A16
PD12,//FSMC_A17
PD13,//FSMC_A18
PE3 ,//FSMC_A19
PE4 ,//FSMC_A20
PE5 ,//FSMC_A21
PE6 ,//FSMC_A22
PE2 ,//FSMC_A23
PG13,//FSMC_A24//STM32F103Z
PG14,//FSMC_A25//STM32F103Z

独立的地址总线管脚:
[注:总线是16Bit情况下,FSMC通过FSMC_NBL1,FSMC_NBL0,区分高低字节.下面W代表WORD,即16BIT字.]
PF0 ,//FSMC_A0 //2^1=2W =4 Bytes //144PIN STM32F103Z
PF1 ,//FSMC_A1 //2^2=4W =8 Bytes//144PIN STM32F103Z
PF2 ,//FSMC_A2 //2^3=8W= 16 Bytes //144PIN STM32F103Z
PF3 ,//FSMC_A3 //2^4=16W =32 Bytes//144PIN STM32F103Z
PF4 ,//FSMC_A4 //2^5=32W =64 Bytes//144PIN STM32F103Z
PF5 ,//FSMC_A5 //2^6=64W =128 Bytes//144PIN STM32F103Z
PF12,//FSMC_A6 //2^7=128W =256 Bytes //144PIN STM32F103Z
PF13,//FSMC_A7 //2^8=256W =512 Bytes //144PIN STM32F103Z
PF14,//FSMC_A8 //2^9= 512W =1k Bytes//144PIN STM32F103Z
PF15,//FSMC_A9 //2^10=1kW =2k Bytes//144PIN STM32F103Z
PG0 ,//FSMC_A10 //2^11=2kW =4k Bytes//144PIN STM32F103Z
PG1 ,//FSMC_A11 //2^12=4kW =8k Bytes//144PIN STM32F103Z
PG2 ,//FSMC_A12 //2^13=8kW =16k Bytes//144PIN STM32F103Z
PG3 ,//FSMC_A13 //2^14=16kW =32k Bytes//144PIN STM32F103Z
PG4 ,//FSMC_A14 //2^15=32kW =64k Bytes//144PIN STM32F103Z
PG5 ,//FSMC_A15 //2^16=64kW =128k Bytes//144PIN STM32F103Z
PD11,//FSMC_A16 //2^17=128kW =256k Bytes
PD12,//FSMC_A17 //2^18=256kW =512k Bytes
PD13,//FSMC_A18 //2^19=512kW =1M Bytes
PE3 ,//FSMC_A19 //2^20=1MW =2M Bytes
PE4 ,//FSMC_A20 //2^21=2MW =4M Bytes
PE5 ,//FSMC_A21 //2^22=4MW =8M Bytes
PE6 ,//FSMC_A22 //2^23=8MW =16M Bytes
PE2 ,//FSMC_A23 //2^24=16MW =32M Bytes //100PIN STM32F103V MAX
PG13,//FSMC_A24 //2^25=32MW =64M Bytes //144PIN STM32F103Z
PG14,//FSMC_A25 //2^26=64MW =128M Bytes //144PIN STM32F103Z

独立的数据总线管脚:
PD14,//FSMC_D0
PD15,//FSMC_D1
PD0 ,//FSMC_D2
PD1 ,//FSMC_D3
PE7 ,//FSMC_D4
PE8 ,//FSMC_D5
PE9 ,//FSMC_D6
PE10,//FSMC_D7
PE11,//FSMC_D8
PE12,//FSMC_D9
PE13,//FSMC_D10
PE14,//FSMC_D11
PE15,//FSMC_D12
PD8 ,//FSMC_D13
PD9 ,//FSMC_D14
PD10,//FSMC_D15
控制信号
PD4,//FSMC_NOE,/RD
PD5,//FSMC_NWE,/WR
PB7,//FSMC_NADV,/ALE
PE1,//FSMC_NBL1,/UB
PE0,//FSMC_NBL0,/LB
PD7,//FSMC_NE1,/CS1
PG9,//FSMC_NE2,/CS2
PG10,//FSMC_NE3,/CS3
PG12,//FSMC_NE4,/CS4
//PD3,//FSMC_CLK
//PD6,//FSMC_NWAIT

2.地址的分配

地址与片选是挂勾的,也就是说器件挂载在哪个片选引脚上,就固定了访问地址范围和FsmcInitStructure.FSMC_Bank

//地址范围:0x60000000~0x63FFFFFF,片选引脚PD7(FSMC_NE1),最大支持容量64MB,
//[在STM32F103V(100脚)上地址范围为A0~A23,最大容量16MB]
FsmcInitStructure.FSMC_Bank =FSMC_Bank1_NORSRAM1;

//地址范围:0x64000000~0x67FFFFFF, 片选引脚PG9(FSMC_NE2),最大支持容量64MB
FsmcInitStructure.FSMC_Bank =FSMC_Bank1_NORSRAM2;

//地址范围:0x68000000~0x6BFFFFFF,片选引脚PG10(FSMC_NE3),最大支持容量64MB 
FsmcInitStructure.FSMC_Bank =FSMC_Bank1_NORSRAM3; 

//地址范围:0x6C000000~0x6FFFFFFF,片选引脚(PG12 FSMC_NE4),最大支持容量64MB
FsmcInitStructure.FSMC_Bank =FSMC_Bank1_NORSRAM4;

3.时序测量

简单原理草图

写数据的时序


读数据的时序

1.数据总线设定为16位宽情况下测量FSMC时序,即

FsmcInitStructure.FSMC_MemoryDataWidth = 	FSMC_MemoryDataWidth_16b;	

使用逻辑分析仪测量(循环执行下面这条语句,下同)的波形

*(volatile uint16_t *)(0x60002468UL)=0xABCD;           

可以看出NADV下降沿瞬间DATABUS上的数据被锁存器锁存,接着NWE低电平,总线输出0xABCD,数据0xABCD被写入0x1234这个地址.

      *(volatile uint16_t*)(0x60002469UL )=0xABCD;              

what?向这个地址写出现了两次总线操作.

为了一探究竟,我引出了控制线.

 *(volatile uint16_t*)(0x60000468UL  )=0xABCD;           

向0x60000468UL写入0xABCD到底会发什么?

从时序图中我们可以看到, 向0x60000468UL在地址(在范围:0x60000000_{0x63FFFFFF内)写入数据,片选引脚PD7(FSMC_NE1)被拉低.而在这之前,数据总线上先产生0x234,于是在NADV下降沿瞬间,数据被锁存在地址锁存器上(A0}A15),与A16~A25(如果有配置的话,会在NE1下降沿同时送出)组合成完整的地址信号.然而有人会问这个0x234是哪来的,你是否注意到它正好等于0x468/2,难道是巧合吗?不是的,在16位数据总线情况下(NORSRAMInitStrc.FSMC_MemoryDataWidth=FSMC_MemoryDataWidth_16b;),
像这样

 *(volatile uint16_t*)(0x60000000|addr)=0xABCD;   

写入一个值,实际在地址线上产生的值是addr/2(即addr>>2),
所以如果我们一定要向addrx写入0xABCD则我们要这样写

*(volatile uint16_t*)(0x60000000|addrx<<1)=0xABCD;

NADV为高电平时, NEW被拉低,NOE为高,且NBL1,NBL0为低,随后数据总线线上产生0xABCD于是0xABCD被写进SRAM的地址0x234中

那如果我们向一个奇数地址像这样

 *(volatile uint16_t*)(0x60000469UL  )=0xABCD;写入值会发生什么呢?

从图中我们可以看到,STM32其实分成了两次字节写的过程,第一次向0x469/2写入0xCD,第二次向0x469/2+1写入0xAB,
有人会问你为什么这样说,NWE为低时总线上不是0xCDAB吗?没错,但是注意NBL1,NBL0的电平组合,NBL1连接到SRAM的nUB,NBL0连接到SRAM的nLB.第一次NEW为低时NBL1为低,NBL0为高,0xCDAB的高位被写入SRAM的0x234,第二次NWE为低时NBL1为高,NBL0为低,0xCDAB的低位被写入SRAM的0x235.
当我们查看反汇编时发现,指令是相同的

0x080036C4 0468      DCW      0x0468 
0x080036C6 6000      DCW      0x6000 
MOVW     r0,#0xABCD
LDR      r1,[pc,#420]  ; @0x080036C4//r1=0x60000468
STRH     r0,[r1,#0x00]


0x080036C4 0469      DCW      0x0469 
0x080036C6 6000      DCW      0x6000 
MOVW     r0,#0xABCD
LDR      r1,[pc,#420]  ; @0x080036C4//r1=0x60000469
STRH     r0,[r1,#0x00]

以上是写入的时序,下面测量读取的时序

首先我们向SRAM的真实地址0x234,0x235分别写入0x8824,0x6507

 *(volatile uint16_t*)(0x60000000UL |0x234 <<1 )=0x8824;
 *(volatile uint16_t*)(0x60000000UL |0x235 <<1 )=0x6507;
 *(volatile uint16_t*)(0x60000000UL |0x236 <<1 )=0x6735;
 *(volatile uint16_t*)(0x60000000UL |0x237 <<1 )=0x2003;
 *(volatile uint16_t*)(0x60000000UL |0x238 <<1 )=0x6219;

然后读取:

tmp=*(volatile uint16_t*)(0x60000468UL  );

如图tmp结果为0x8824
再试

  tmp=*(volatile uint16_t*)(0x60000469UL  );

nUB=nLB=0;按16bit读
从0x234读得0X8824取高字节"88"作tmp低8位
从0x235读得0X6507取低字节"07"作tmp高8位
最终tmp=0x0788

接下来验证更特殊的

*(volatile uint8_t*)(0x60000469UL   )=0xABCD; 

由于NBL1=0,NBL0=1,0xCD被写入0x234的高地址,
数据总线上出现的值是0xCDNN, NN是随机数据,不过一般是和高位一样的值

*(volatile uint8_t*)(0x60000468UL   )=0xABCD; 

由于NBL1=1,NBL0=0,0xCD被写入0x234的低地址,
数据总线上出现的值是0xNNCD,NN是随机数据

验证字节读取的
首先我们向SRAM的真实地址0x234,0x235分别写入0x8824,0x6507

*(volatile uint16_t*)(0x60000000UL |0x234 <<1 )=0x8824;
*(volatile uint16_t*)(0x60000000UL |0x235 <<1 )=0x6507;

然后这样读取

tmp=*(volatile uint8_t*)(0x60000469UL   );//对奇地址的单字节读取,数据总线的高8位被返回 tmp=0x88

tmp=*(volatile uint8_t*)(0x60000468UL   );//对偶地址的单字节读取,数据总线的低8位被返回 tmp=0x24

还有更特殊的没有,有!

 *(volatile int64_t*)(0x60000468UL)=0XABCDEF1234567890;//0XABCD EF12 3456 7890,如图,分别进行了4次操作才写完:

*(volatile int64_t*)(0x60000469UL)=0XABCDEF1234567890;//0XABCD EF12 3456 7890,如图,对奇地址写比偶地址多一次操作:

 *(volatile uint16_t*)(0x60000000UL |0x234 <<1 )=0x8824;
 *(volatile uint16_t*)(0x60000000UL |0x235 <<1 )=0x6507;
 *(volatile uint16_t*)(0x60000000UL |0x236 <<1 )=0x6735;
 *(volatile uint16_t*)(0x60000000UL |0x237 <<1 )=0x2003;
 *(volatile uint16_t*)(0x60000000UL |0x238 <<1 )=0x6219;

 tmp=*(volatile int64_t*)(0x60000469UL);// tmp=0x1920036735650788 

 tmp=*(volatile int64_t*)(0x60000468UL); //tmp=0x2003673565078824 

1.数据总线设定为8位宽情况下测量FSMC时序,即
FsmcInitStructure.FSMC_MemoryDataWidth = FSMC_MemoryDataWidth_8b;

*(volatile uint16_t*)(0x60000468UL  )=0xABCD; 

*(volatile uint16_t*)(0x60000469UL  )=0xABCD;

*(volatile uint16_t*)(0x60000468UL  )=0x3344;
*(volatile uint16_t*)(0x60000469UL  )=0xABCD;

tmp=(volatile uint16_t)(0x60000469UL ); //tmp=0xabcd

tmp=*(volatile uint16_t*)(0x60000468UL  );

tmp=0xcd44

tmp=*(volatile uint8_t*)(0x60000468UL  );

tmp=0x44

tmp=*(volatile uint8_t*)(0x60000469UL  ); 
tmp=0xcd

*(volatile uint8_t*)(0x60000469UL   )=0xABCD;

*(volatile uint8_t*)(0x60000468UL   )=0xABCD;

tmp=*(volatile uint64_t*)(0x60000468UL  );
tmp=0x2003673565ABCD44

tmp=*(volatile uint64_t*)(0x60000469UL  );//tmp=0x192003673565ABCD

*(volatile uint64_t*)(0x60000469UL  )=0XABCDEF1234567890;  

*(volatile uint64_t*)(0x60000468UL  )=0XABCDEF1234567890;  

鼓捣这么多,看得头都大了,先写到这,以后有发现再补充了

参考:
ST,RM0008 , Reference manual
http://www.cnblogs.com/zpehome/p/3477011.html