基于FPGA和STM32的FSMC通信-电子工程世界

1、FSMC简介：FSMC即灵活的静态存储控制器，FSMC管理1GB空间，拥有4个Bank连接外部存储器，每个Bank有独立的片选信号和独立的时序配置；支持的存储器类型有SRAM、PSRAM、NOR/ONENAND、ROM、LCD接口（支持8080和6800模式）、NANDFlash和16位的PCCard。

2、在设计中将FPGA当做SRAM来驱动，使用库函数来实现FSMC的初始化配置代码如下：

//初始化外部SRAM
void FSMC_SRAM_Init(void)
{
   FSMC_NORSRAMInitTypeDef FSMC_NORSRAMInitStructure; //定义FSMC初始化的结构体变量
   FSMC_NORSRAMTimingInitTypeDef readWriteTiming;           //用来设置FSMC读时序和写时序的指针变量
   GPIO_InitTypeDef GPIO_InitStructure;            //初始化FSMC总线的IO口

    RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOD|RCC_APB2Periph_GPIOE|RCC_APB2Periph_AFIO,ENABLE);
RCC_AHBPeriphClockCmd(RCC_AHBPeriph_FSMC,ENABLE);    //开启FSMC的时钟
    GPIO_InitStructure.GPIO_Pin =GPIO_Pin_8|GPIO_Pin_9|GPIO_Pin_10|GPIO_Pin_14

|GPIO_Pin_10|GPIO_Pin_11|GPIO_Pin_12|GPIO_Pin_13|GPIO_Pin_14|GPIO_Pin_15;
   GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
    GPIO_Init(GPIOE, &GPIO_InitStructure);


   GPIO_InitStructure.GPIO_Mode = GPIO_Mode_Out_PP;
   GPIO_InitStructure.GPIO_Pin = GPIO_Pin_2|GPIO_Pin_6;
   GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
   GPIO_Init(GPIOE, &GPIO_InitStructure);

   readWriteTiming.FSMC_AddressSetupTime = 14;
   readWriteTiming.FSMC_AddressHoldTime = 0x00;
    readWriteTiming.FSMC_DataSetupTime = 16;
   readWriteTiming.FSMC_BusTurnAroundDuration = 0;
   readWriteTiming.FSMC_CLKDivision = 0x00;
   readWriteTiming.FSMC_DataLatency = 0x00;
   readWriteTiming.FSMC_AccessMode = FSMC_AccessMode_A;


   FSMC_NORSRAMInitStructure.FSMC_Bank=FSMC_Bank1_NORSRAM1;
   FSMC_NORSRAMInitStructure.FSMC_DataAddressMux = FSMC_DataAddressMux_Disable;
   FSMC_NORSRAMInitStructure.FSMC_MemoryType =FSMC_MemoryType_SRAM;
FSMC_NORSRAMInitStructure.FSMC_MemoryDataWidth= FSMC_MemoryDataWidth_16b;
FSMC_NORSRAMInitStructure.FSMC_BurstAccessMode=FSMC_BurstAccessMode_Disable;
   FSMC_NORSRAMInitStructure.FSMC_WaitSignalPolarity = FSMC_WaitSignalPolarity_Low;
   FSMC_NORSRAMInitStructure.FSMC_AsynchronousWait=FSMC_AsynchronousWait_Disable;
   FSMC_NORSRAMInitStructure.FSMC_WrapMode = FSMC_WrapMode_Disable;
   FSMC_NORSRAMInitStructure.FSMC_WaitSignalActive = FSMC_WaitSignalActive_BeforeWaitState;
   FSMC_NORSRAMInitStructure.FSMC_WriteOperation = FSMC_WriteOperation_Enable;
   FSMC_NORSRAMInitStructure.FSMC_WaitSignal = FSMC_WaitSignal_Disable;
   FSMC_NORSRAMInitStructure.FSMC_ExtendedMode = FSMC_ExtendedMode_Disable;
   FSMC_NORSRAMInitStructure.FSMC_WriteBurst = FSMC_WriteBurst_Disable;
   FSMC_NORSRAMInitStructure.FSMC_ReadWriteTimingStruct = &readWriteTiming;
   FSMC_NORSRAMInitStructure.FSMC_WriteTimingStruct = &readWriteTiming;
   FSMC_NORSRAMInit(&FSMC_NORSRAMInitStructure);
   FSMC_NORSRAMCmd(FSMC_Bank1_NORSRAM1, ENABLE);
   delay_ms(50)；
}

FPGA代码：

//fsmc read / write ep4ce6 demo

module fsmc(
   ab,     //address
   db,      //data
   wrn,      //wr
   rdn,      //rd
   resetn, //resetn
   csn,      //cs
   clk
   );

   input[2:0]   ab;
   inout[15:0] db;
   input wrn;
   input rdn;
   input resetn;
   input csn;
   input clk;

   reg [15:0] ina = 16'd0; //存储数据供ARM读
   reg [15:0] inb = 16'd1;
   reg [15:0] inc = 16'd2;
   reg [15:0] ind = 16'd3;
   reg [15:0] ine = 16'd4;
   reg [15:0] inf = 16'd5;
   reg [15:0] ing = 16'd6;
   reg [15:0] inh = 16'd7;


   reg [15:0] outa;
   reg [15:0] outb;
   reg [15:0] outc;
   reg [15:0] outd;
   reg [15:0] oute;
   reg [15:0] outf;
   reg [15:0] outg;
   reg [15:0] outh;

   wire rd;
   wire wr;

   reg [15:0] indata;

   assign rd = !(csn & rdn); //get rd pulse ____|~~~~|______
   assign wr = !(csn & wrn) ; //get wr pulse ____|~~~~|______

   /*********当不进行读写操作时db=indata*********
   *********当进行写操作时db=16'hzzzz**********
   *********当进行读操作时db=indata**********/
   assign db = rd? indata:16'hzzzz;


   //write data, 根据地址线选择八个空间写入，每个空间16位
   always @(negedge wr or negedge resetn)
   begin
       if(!resetn)begin
           outa <= 16'h0000;
           outb <= 16'h0000;
           outc <= 16'h0000;
           outd <= 16'h0000;
           oute <= 16'h0000;
           outf <= 16'h0000;
           outg <= 16'h0000;
           outh <= 16'h0000;
       end   else begin
       case (ab)
           3'b000:outa <= db;
           3'b001:outb <= db;
           3'b010:outc <= db;
           3'b011:outd <= db;
           3'b100:oute <= db;
           3'b101:outf <= db;
           3'b110:outg <= db;
           3'b111:outh <= db;
           default:;
       endcase
       end
   end


   //red data 根据地址线选择8个空间读取，每个空间 16位
   always @(rd or !resetn)
   begin
       if(!resetn)indata <= 16'h0000;
       else begin
       case (ab)
           3'b000:indata <= ina;
           3'b001:indata <= inb;
           3'b010:indata <= inc;
           3'b011:indata <= ind;
           3'b100:indata <= ine;
           3'b101:indata <= inf;
           3'b110:indata <= ing;
           3'b111:indata <= inh;
           default:;
       endcase
       end
   end
endmodule