硬件方面:IS62WV512163 R8 e2 g# D, Y! J; Y
软件方面:MDK/ T9 R7 Z, y. H$ F5 k8 a2 U
: p0 R; d, Z% b; q修改startup_xxx.s 堆栈地址并在__main函数前初始化FSMC
, [* b% H' U9 I3 p- G1 ~. s修改.sct文件(分散加载),添加外部SRAM的使用空间及大小。1 G" U8 N7 y, i& B Y. |
具体步骤如下:
% E' V+ D5 D# Z$ Q7 v- //startup_stm32f407xx.s部分9 |5 I) B+ [2 t0 k
- ; Vector Table Mapped to Address 0 at Reset
) `! |: f2 L" f& W" S+ Z2 A - AREA RESET, DATA, READONLY
2 Y g* }1 ]7 t1 \- `! ? - EXPORT __Vectors
+ a: X; @# l( [! | - EXPORT __Vectors_End
0 d* G# H- h& H+ ^! K }7 D - EXPORT __Vectors_Size8 f! a+ M" k5 L7 G
-
! P. p5 m; H; Z5 C1 W - __Vectors DCD 0x20000100 ; Top of Stack
( v$ E( V9 v* r! A6 Z - DCD Reset_Handler ; Reset Handler
6 S! F9 p9 g/ f3 T - DCD NMI_Handler ; NMI Handler4 j& ^7 ]/ D# ^$ e+ W! \. X }, z
- ..." @5 k0 W8 S4 F M. v
- ...) [: G3 W- e( d/ L
- ...
& U- m2 D, J/ p% J; f - IMPORT SystemInit
, h; T9 q6 p4 f0 F - IMPORT FSMC_SRAM_Init( K Q. l0 E9 x
- IMPORT __main! ^7 W- q f9 J# S; }1 y) M5 \3 e
- LDR R0, =SystemInit! S5 f( N5 H$ B- L- u: m
- BLX R02 C/ k8 L: T" Q8 ]
- LDR R0, =FSMC_SRAM_Init
1 l1 O; P% H2 x! Q# ? - BLX R0 7 P$ X W( w" E l+ S! w
- LDR R0, =__main5 c' b- D' \$ l# J/ r
- BX R0& n$ P5 Q+ ^' l3 |+ ]' m
- ENDP
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复制代码 0x20000100 替换 __initial_sp# z( g6 W" U; ]
添加IMPORT FSMC_SRAM_Init
3 {5 @- W# s' }) A/ Y! d2 Y0 x' W添加LDR R0, =FSMC_SRAM_Init和LX R0。敲黑板这两句必须在__main前面/ e l( V0 D/ ]% K" b7 k
这里的FSMC_SRAM_Init函数是使用正点原子探索者407寄存器版本的,里面所使用的变量只能是创建在内部SRAM哦,一旦用了外部SRAM就会触发HardFault,后果你懂的。所以尽量使用寄存器来初始化配置FSMC。, ]3 d; D7 Z( c7 J
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/ x) q |+ f; E% |7 c2 { f接下来就是第二部分,配置内存分配空间
* I# s; K5 G% s1 w+ `按上图配置,要注意的是default一定要勾选,不然内存是不会分配到外部SRAM的。当然了你用__atrribute__来指定分配也是可以用的,但是有一个问题就是你不能初始化赋值,管你是非零还是零赋值,通通没用,原因何在,我也不知道。希望高人指点一二
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: M: W( g3 I" h之后就可以愉快的使用外部SRAM啦。+ \3 y3 e2 J4 B) k( Y& y( }
编写代码的时候使用方式与内部SRAM无异。
- _. c" F; O! J不过速度嘛…肯定比使用内部SRAM要慢的,毕竟FSMC操作外部SRAM的速度就那么大。
5 _, k7 F6 n. A" M' ?$ X$ r! B- ?* E
3 U5 V. W# [. Z/ [( y最后附上我改写后的纯寄存器版本的FSMC_SRAM_Init6 j g8 h9 l A
经测试能用在STM32F407上,其他芯片请自行修改。4 G% E d1 x: j( ^
- void FSMC_SRAM_Init(void)' o! K3 {( W" S; q$ ~/ @0 x
- {9 |1 I5 s, O: T7 Q
- /*-- GPIOs Configuration -----------------------------------------------------*/
$ R2 l1 O' I: R- a - /* Enable GPIOD, GPIOE, GPIOF and GPIOG interface clock */
8 m4 N. }7 X5 G" {: d& d I* X- a - RCC->AHB1ENR |= 0x00000078;* p0 y, K3 Q- A! {
- " |/ W/ D8 [$ ]+ o# r% v
- //PD0,1,4,5,8~15 100M AF OUT_PP UP
7 T* m% i" J& ]% {, k, y b - //PE0,1,7~15 100M AF OUT_PP UP
1 P+ f$ U) j2 Q: q/ F - //PF0~5,12~15 100M AF OUT_PP UP$ `) P0 a1 a: X
- //PG0~5,10 100M AF OUT_PP UP
7 U. v% O4 s' q4 j -
! P- |: L9 f" L, g: E! r( k, z8 Z$ L - /* Connect PDx pins to FMC Alternate function */. ?: L4 v* J% `, \
- GPIOD->AFR[0] = 0x00CC00CC;; l0 l( k" Y7 }5 t3 l, P; e
- GPIOD->AFR[1] = 0xCCCCCCCC;
# L& t0 X1 v* N* O - /* Configure PDx pins in Alternate function mode */ 1 W3 s. m8 u1 y; `! {4 c; U7 W
- GPIOD->MODER = 0xAAAA0A0A;0 i: Y4 v8 d5 a8 I+ I. A
- /* Configure PDx pins speed to 100 MHz */
& F7 b" n7 C: w7 ?5 k) N8 S( m) `" { - GPIOD->OSPEEDR = 0xFFFF0F0F;
" P8 J! a1 N* s - /* Configure PDx pins Output type to push-pull */ % g9 [0 h B6 S( D5 U
- GPIOD->OTYPER = 0x00000000;
4 d8 i' R% [ A( I - /* pull-up for PDx pins */
' s3 a3 g3 o7 u, o - GPIOD->PUPDR = 0x55550505;) n0 g4 p7 C) y6 Z( u! E
- 2 E0 c$ F# i, @6 q+ ~, c) G
- /* Connect PEx pins to FMC Alternate function */
+ J5 g3 s3 W( l( U' w& k - GPIOE->AFR[0] = 0xC00000CC;
6 E7 U# a* Q- c0 O. m" r - GPIOE->AFR[1] = 0xCCCCCCCC;( l" q3 V+ @' e7 S) f% `3 v
- /* Configure PEx pins in Alternate function mode */
! Y. r& c2 v. _0 ] - GPIOE->MODER = 0xAAAA800A;
d' |! s3 ]& y1 v - /* Configure PEx pins speed to 100 MHz */
1 l! u7 ^* x/ d, Z - GPIOE->OSPEEDR = 0xFFFFC00F;
1 H! [4 n# d$ q4 k' t - /* Configure PEx pins Output type to push-pull */ 6 E/ q9 X# x, b4 }
- GPIOE->OTYPER = 0x00000000;
9 e" | `: h A9 d! c7 q0 b2 \ - /* pull-up for PEx pins */
+ M% y# n& H& n9 J1 f% l- e/ \/ l - GPIOE->PUPDR = 0x55554005;
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- /* Connect PFx pins to FMC Alternate function */
3 I# d8 s+ v* L6 x, B - GPIOF->AFR[0] = 0x00CCCCCC;6 L9 H: m$ b' r' _5 |% @8 G: d, @
- GPIOF->AFR[1] = 0xCCCC0000;) J8 V" w2 R( m) D8 Z& s0 N$ f" _( y
- /* Configure PFx pins in Alternate function mode */
, L% G( g8 ?( b+ e+ ?! u) Z2 @" o+ p. ^. s - GPIOF->MODER = 0xAA000AAA;. `# r% u1 ~6 Q* a
- /* Configure PFx pins speed to 100 MHz */ 3 Q5 j7 _% D* k/ O# w e
- GPIOF->OSPEEDR = 0xFF000FFF;$ i8 R- ]9 p4 Y, A1 ?- d
- /* Configure PFx pins Output type to push-pull */
/ E2 u% C9 Z: n6 I4 { - GPIOF->OTYPER = 0x00000000;/ A, M* _3 A; X3 i
- /* pull-up for PFx pins */
$ J, v; {% @% X( U# V - GPIOF->PUPDR = 0x55000555;" V$ D8 n( A1 f! V1 \& v
-
! c! z8 F: j: x - /* Connect PGx pins to FMC Alternate function */
' m. l: U0 M8 X2 D, l. d - GPIOG->AFR[0] = 0x00CCCCCC;
6 Q z8 d% {, R - GPIOG->AFR[1] = 0x00000C00;
$ s$ G# l! N" V) \: J6 s' T - /* Configure PGx pins in Alternate function mode */
- j5 ~: J0 H" t' K0 [, T: [& M - GPIOG->MODER = 0x00200AAA;
( V+ z) k& z P' K - /* Configure PGx pins speed to 100 MHz */
* g7 O6 A6 ^3 V5 f, ? - GPIOG->OSPEEDR = 0x00300FFF;' V5 P" f% S- p- L, ?) N7 z* U
- /* Configure PGx pins Output type to push-pull */
/ T) q) w0 J. ]5 \+ q' d! `& V2 L - GPIOG->OTYPER = 0x00000000;
8 }. N \4 T$ N' `, V9 h- N - /* pull-up for PGx pins */ . M9 y0 K7 R8 J* }- p( R+ f& I
- GPIOG->PUPDR = 0x00100555;+ C* X7 C8 P1 y0 F) r
-
# S$ _$ Y) ?9 r - /*-- FMC/FSMC Configuration --------------------------------------------------*/
! C7 W$ L8 ?3 T - /* Enable the FMC/FSMC interface clock */4 ?- X# p1 e! n0 F# ]5 L5 N% Y a
- RCC->AHB3ENR |= 0x00000001;6 @! `8 Z4 ?5 \% P
- 2 v9 b/ Y5 V4 [- u
- //寄存器清零
5 `+ j) ?- \8 N# R- o5 w - //bank1有NE1~4,每一个有一个BCR+TCR,所以总共八个寄存器。 ?- a4 ^3 Q: t& m' C
- //这里我们使用NE3 ,也就对应BTCR[4],[5]。 - c9 |; {; L2 R9 B4 _: @% i" y$ H
- FSMC_Bank1->BTCR[4]=0X00000000;
1 p# V$ b7 v$ _& \% d" Q( U - FSMC_Bank1->BTCR[5]=0X00000000;$ f" Y+ r4 p0 O4 F, i6 _, v
- FSMC_Bank1E->BWTR[4]=0X00000000;
6 H3 |' _' w5 o9 e h) Y - //操作BCR寄存器 使用异步模式,模式A(读写共用一个时序寄存器)5 o, w- R' t5 _' L# O
- //BTCR[偶数]:BCR寄存器;BTCR[奇数]:BTR寄存器/ }3 @4 {8 L- z6 k& b* L* T
- FSMC_Bank1->BTCR[4]|=1<<12;//存储器写使能, m5 R8 f# X5 [" y9 S7 g& m
- FSMC_Bank1->BTCR[4]|=1<<4; //存储器数据宽度为16bit `- L0 L0 W( P3 P( v$ }* M
- //操作BTR寄存器 (HCLK=168M, 1个HCLK=6ns
, i3 J( t3 \0 E* F - FSMC_Bank1->BTCR[5]|=8<<8; //数据保持时间(DATAST)为9个HCLK 6*9=54ns 5 P. X( r) j' c$ ` m3 R7 q' J
- FSMC_Bank1->BTCR[5]|=0<<4; //地址保持时间(ADDHLD)未用到 1 a! u q e1 Y% P7 X1 v- n
- FSMC_Bank1->BTCR[5]|=0<<0; //地址建立时间(ADDSET)为0个HCLK 0ns
r; }$ X. ]& B5 K7 v - //闪存写时序寄存器
% ?6 G3 U- g1 {: Q9 w4 X - FSMC_Bank1E->BWTR[4]=0x0FFFFFFF;//默认值4 B( U: e* m& K/ |! d
- //使能BANK1区域3. U9 B; p2 ]7 c: o
- FSMC_Bank1->BTCR[4]|=1<<0;, p* y/ e- X) K! H
- }
+ t. S+ m( Q! H2 p - ————————————————
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复制代码
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