FPGA与MCU的程序思路-电子发烧友网

FPGA以9600的波特率向单片机发送32位数据，然后单片机对数据进行解析，显示在显示屏上面

波特率的产生：9600bps是指每秒钟发送9600个bit，即1bit的时间为1/9600，fpga板子自带50M晶振，那么一bit的时间时1/9600/1/50M

在没有检验位的情况下，每一帧数据是10位第一位起始位 0 2-9位数据（低位在前，高位在后），第十位终止位 1

FPGA程序思路：首先由fpga计数，每隔一段时间产生一个bps_clk,也就是波特率的驱动时钟，发送状态机共分为7个状态

IDLE ：发送起始标志为 TX_1 ：发送32数据的高八位，其中低位在前，高位在后 ...... STOP ：终止标志位 STOP_1 : 是专门用来延时的，刚开始没有延时状态

的情况下，FPGA向单片机发送数据过快，非常占用单片机的中断资源，所以加了一个延时模块 stop ，作用是：每发完一次数据等待100ms然后再发第二次数据，这样的

单片机就有时间干别的事情了。

MCU程序思路：首先在中断函数里面将FPGA发送过来的数据存到一个数组里面来处理，detect-uart()函数是用来分析数组的，首先检测数组里面的起始标志 ‘t’,如果没有检测到

终止标志位‘x’的话，对中间数据进行移位处理，还原以前的32位宽的数据，由于在数据传送时有误码的情况，所以在display中加了三级缓存，来减少出错的可能性。

module    uart_tx(
        //global clock
        input            clk,
        input            rst_n,
        //uart    interface
        output    reg        uart_tx,
        //user    interface
        input    [31:0]    pinlv,
        input            pinlv_value
);

parameter    BPS_9600 = 5208;
//parameter    BPS_9600 = 10;
//count for bps_clk
reg        [14:0]        cnt_bps_clk;
always @(posedge clk or negedge rst_n)
begin
    if(!rst_n)
        cnt_bps_clk <= 1'b0;
    else if(pinlv_value == 0)
        cnt_bps_clk <= 1'b0;
    else if(cnt_bps_clk == BPS_9600 - 1)
        cnt_bps_clk <= 1'b0;
    else
        cnt_bps_clk <= cnt_bps_clk + 1;
end

reg        [31:0]        cnt_bps_stop;
wire                stop_done;
always @(posedge clk or negedge rst_n)
begin
    if(!rst_n)
        cnt_bps_stop <= 0;
    else if(state == STOP)
        cnt_bps_stop <= 0;
    else if(cnt_bps_stop > 50_000_00)
        cnt_bps_stop <= 0;
    else
        cnt_bps_stop <= cnt_bps_stop + 1;

end
assign    stop_done = (cnt_bps_stop == 49_000_00)? 1 : 0;
//clk for bps
reg                    bps_clk;
always @(posedge clk or negedge rst_n)
begin
    if(!rst_n)
        bps_clk <= 1'b0;
    else if(cnt_bps_clk == 1)
        bps_clk <= 1'b1;
    else
        bps_clk <= 1'b0;
end
//cnt for bps
reg        [14:0]        bps_cnt;
always @(posedge clk or negedge rst_n)
begin
    if(!rst_n)
        bps_cnt <= 1'b0;
    else if(bps_cnt == 10)
        bps_cnt <= 0;
    else if(bps_clk)
        bps_cnt <= bps_cnt + 1'b1;
    else
        bps_cnt <= bps_cnt;
end

//tx state
localparam    IDLE        =    4'd0;
localparam    TX_1        =    4'd1;
localparam    TX_2        =    4'd2;
localparam    TX_3        =    4'd3;
localparam    TX_4        =    4'd4;
localparam    STOP        =    4'd5;
localparam    STOP_1        =    4'd6;
//cnt state
reg        [3:0]        state;
always @(posedge clk or negedge rst_n)
begin
    if(!rst_n)
        state <= IDLE;
    else if(state == STOP_1 && stop_done)
        state <= IDLE;
    else if(bps_cnt == 10 && (state != STOP_1))
        state <= state + 1;
end


// state
always @(posedge clk )
begin
    if(bps_clk)
    begin
        case(state)
        IDLE :   // 't'  di -- gao
        begin
            case(bps_cnt)
            4'd0     : uart_tx <= 0; //begin
            
            4'd1     : uart_tx <= 0;//data
            4'd2     : uart_tx <= 0;
            4'd3     : uart_tx <= 1;
            4'd4     : uart_tx <= 0;
            4'd5     : uart_tx <= 1;
            4'd6    : uart_tx <= 1;
            4'd7     : uart_tx <= 1;
            4'd8     : uart_tx <= 0;
            
            4'd9     : uart_tx <= 1; //stop
            default : uart_tx <= 1;
            endcase
        end
        
        TX_1 : //tx_1byte
        begin
            case(bps_cnt)
            4'd0 : uart_tx <= 0; //begin
            
            4'd1     : uart_tx <= pinlv[24];//data
            4'd2     : uart_tx <= pinlv[25];
            4'd3     : uart_tx <= pinlv[26];
            4'd4     : uart_tx <= pinlv[27];
            4'd5     : uart_tx <= pinlv[28];
            4'd6    : uart_tx <= pinlv[29];
            4'd7     : uart_tx <= pinlv[30];
            4'd8     : uart_tx <= pinlv[31];
            
            4'd9     : uart_tx <= 1; //stop
            default : uart_tx <= 1;
            endcase        
        end
        
        TX_2 : //tx_1byte
        begin
            case(bps_cnt)
            4'd0 : uart_tx <= 0; //begin
            
            4'd1     : uart_tx <= pinlv[16];//data
            4'd2     : uart_tx <= pinlv[17];
            4'd3     : uart_tx <= pinlv[18];
            4'd4     : uart_tx <= pinlv[19];
            4'd5     : uart_tx <= pinlv[20];
            4'd6    : uart_tx <= pinlv[21];
            4'd7     : uart_tx <= pinlv[22];
            4'd8     : uart_tx <= pinlv[23];
            
            4'd9     : uart_tx <= 1; //stop
            default : uart_tx <= 1;
            endcase        
        end    


        TX_3 : //tx_1byte
        begin
            case(bps_cnt)
            4'd0 : uart_tx <= 0; //begin
            
            4'd1     : uart_tx <= pinlv[8];//data
            4'd2     : uart_tx <= pinlv[9];
            4'd3     : uart_tx <= pinlv[10];
            4'd4     : uart_tx <= pinlv[11];
            4'd5     : uart_tx <= pinlv[12];
            4'd6    : uart_tx <= pinlv[13];
            4'd7     : uart_tx <= pinlv[14];
            4'd8     : uart_tx <= pinlv[15];
            
            4'd9     : uart_tx <= 1; //stop
            default : uart_tx <= 1;
            endcase                
        end    

        TX_4 : //tx_1byte
        begin
            case(bps_cnt)
            4'd0 : uart_tx <= 0; //begin
            
            4'd1     : uart_tx <= pinlv[0];//data
            4'd2     : uart_tx <= pinlv[1];
            4'd3     : uart_tx <= pinlv[2];
            4'd4     : uart_tx <= pinlv[3];
            4'd5     : uart_tx <= pinlv[4];
            4'd6    : uart_tx <= pinlv[5];
            4'd7     : uart_tx <= pinlv[6];
            4'd8     : uart_tx <= pinlv[7];
            
            4'd9     : uart_tx <= 1; //stop
            default : uart_tx <= 1;
            endcase                    
        end
        
        STOP :   // 'x'  di -- gao
        begin
            case(bps_cnt)
            4'd0 : uart_tx <= 0; //begin
            
            4'd1     : uart_tx <= 0;//data
            4'd2     : uart_tx <= 0;
            4'd3     : uart_tx <= 0;
            4'd4     : uart_tx <= 1;
            4'd5     : uart_tx <= 1;
            4'd6    : uart_tx <= 1;
            4'd7     : uart_tx <= 1;
            4'd8     : uart_tx <= 0;
            
            4'd9     : uart_tx <= 1; //stop
            default : uart_tx <= 1;
            endcase
        end
        
        STOP_1 :
        begin
            uart_tx <= 1;
        end
        
        default :
            uart_tx <= 1;
        endcase
    end
    else
        uart_tx <= uart_tx;

end




endmodule

/*************** 用户定义参数 *****************************/

#define MAIN_Fosc        11059200L    //define main clock

#define Baudrate1        9600        //define the baudrate, 如果使用BRT做波特率发生器,则波特率跟串口2一样
                                    //12T mode: 600~115200 for 22.1184MHZ, 300~57600 for 11.0592MHZ

#define Baudrate2        19200        //define the baudrate2,
                                    //12T mode: 600~115200 for 22.1184MHZ, 300~57600 for 11.0592MHZ

#define        BUF_LENTH    20        //定义串口接收缓冲长度

/**********************************************************/

#include    

sfr AUXR1 = 0xA2;
sfr    AUXR = 0x8E;
sfr S2CON = 0x9A;    //12C5A60S2双串口系列
sfr S2BUF = 0x9B;    //12C5A60S2双串口系列
sfr IE2   = 0xAF;    //STC12C5A60S2系列
sfr BRT   = 0x9C;

unsigned char     uart1_wr;        //写指针
unsigned char     uart1_rd;        //读指针
unsigned char     xdata RX1_Buffer[BUF_LENTH];
bit        B_TI;

unsigned char     uart2_wr;        //写指针
unsigned char     uart2_rd;        //读指针
unsigned char     xdata RX2_Buffer[BUF_LENTH];
bit        B_TI2;
long    temp1 = 0;
long    temp2 = 0;
long    temp_buf1 = 0;
long    temp_buf2 = 0;
long    temp_buf3 = 0;
long    temp_buf  = 0;
long    ce = 9999;
/****************** 编译器自动生成，用户请勿修改 ************************************/

#define T1_TimerReload    (256 - MAIN_Fosc / 192 / Baudrate1)            //Calculate the timer1 reload value    at 12T mode
#define BRT_Reload        (256 - MAIN_Fosc / 12 / 16 / Baudrate2)        //Calculate BRT reload value

#define    TimeOut1        (28800 / (unsigned long)Baudrate1 + 2)
#define    TimeOut2        (28800 / (unsigned long)Baudrate2 + 2)

#define    TI2                (S2CON & 0x02) != 0
#define    RI2                (S2CON & 0x01) != 0
#define    CLR_TI2()        S2CON &= ~0x02
#define    CLR_RI2()        S2CON &= ~0x01

/**********************************************************/

/******************** 本地函数声明 ***************/
void    uart1_init(void);

void    UART1_TxByte(unsigned char dat);

void    PrintString1(unsigned char code *puts);

void delay(char x)
{
    char i = 0;
    char t= 0;
    for(i = 0;i<110;i++)
    {
        for(t = 0;t < x;t++);
    }
}

void detect_uart()
{
    char i = 0;
    char flag = 0;
    temp1 = 0;
    for(i = 0;i <= uart1_wr ; i++)
    {
    //    UART1_TxByte(RX1_Buffer[i]);
        if(flag)
        {
            if(RX1_Buffer[i] != 'x' )
            {
                temp1 = temp1 << 8 ;
                temp1 = temp1 + RX1_Buffer[i];
    //            UART1_TxByte(RX1_Buffer[i]);
            }
            else
                temp2 = temp1;
        }
        if(RX1_Buffer[i] == 't')
        {
            flag = 1;
        }
    }
}

//void ceshi()
//{
//    ce = 0;
//    ce = ce << 8 ;
//    ce = ce + 0xff;
//    ce = ce    << 8 ;
//    ce = ce + 0x0c;
//    ce = ce << 8 ;
//    ce = ce + 0xcc;
//    ce = ce    << 8 ;
//    ce = ce + 0xcc;
////    ce = 9999;
//}

void display()
{
    char flag = 0;
    temp_buf3 = temp_buf2;
    temp_buf2 = temp_buf1;
     temp_buf1 = temp2;
    if(temp_buf3 == temp2)
    {
        temp_buf = temp2;
    }
    else
    {
        temp_buf = temp_buf;
    }
    UART1_TxByte('S');UART1_TxByte(' ');UART1_TxByte(' ');UART1_TxByte(' ');UART1_TxByte(' ');
    if(temp_buf/100000000 == 0) //bai M
    {
        UART1_TxByte(' ');
    }
    else
    {
        UART1_TxByte(temp_buf/100000000 + 0x30);
        flag  = 1;
    }

    if(temp_buf/10000000%10 == 0 )    //shi M
    {
        if(!flag)
        {
            UART1_TxByte(' ');
        }
        else
        {
             UART1_TxByte(0x30);
        }
    }
    else
    {
         UART1_TxByte(temp_buf/10000000%10 + 0x30);
        flag = 1;
    }

    if(temp_buf/1000000%10 == 0 )  //M
    {
        if(!flag)
        {
            UART1_TxByte(' ');
        }
        else
        {
             UART1_TxByte(0x30);
        }
    }
    else
    {
         UART1_TxByte(temp_buf/1000000%10 + 0x30);
        flag = 1;
    }

    if(temp_buf/100000%10 == 0 )  //bai K
    {
        if(!flag)
        {
            UART1_TxByte(' ');
        }
        else
        {
             UART1_TxByte(0x30);
        }
    }
    else
    {
         UART1_TxByte(temp_buf/100000%10 + 0x30);
        flag = 1;
    }

    if(temp_buf/10000%10 == 0 )  //shi k
    {
        if(!flag)
        {
            UART1_TxByte(' ');
        }
        else
        {
             UART1_TxByte(0x30);
        }
    }
    else
    {
         UART1_TxByte(temp_buf/10000%10 + 0x30);
        flag = 1;
    }

    if(temp_buf/1000%10 == 0 )  // K
    {
        if(!flag)
        {
            UART1_TxByte(' ');
        }
        else
        {
             UART1_TxByte(0x30);
        }
    }
    else
    {
         UART1_TxByte(temp_buf/1000%10 + 0x30);
        flag = 1;
    }

    if(temp_buf/100%10 == 0 )  //bai
    {
        if(!flag)
        {
            UART1_TxByte(' ');
        }
        else
        {
             UART1_TxByte(0x30);
        }
    }
    else
    {
         UART1_TxByte(temp_buf/100%10 + 0x30);
        flag = 1;
    }

    if(temp_buf/10%10 == 0 )  //shi
    {
        if(!flag)
        {
            UART1_TxByte(' ');
        }
        else
        {
             UART1_TxByte(0x30);
        }
    }
    else
    {
         UART1_TxByte(temp_buf/10%10 + 0x30);
        flag = 1;
    }

    if(temp_buf%10 == 0 )  //ge
    {
        if(!flag)
        {
            UART1_TxByte(' ');
        }
        else
        {
             UART1_TxByte(0x30);
        }
    }
    else
    {
         UART1_TxByte(temp_buf%10 + 0x30);
        flag = 1;
    }

}


void    main(void)
{
    char i = 0;
    uart1_rd = 0;
    uart1_wr = 0;
    uart2_rd = 0;
    uart2_wr = 0;

//    AUXR |=  0x01;        //串口1使用独立波特率发生器, 波特率跟串口2一样
    AUXR1 |= (1<<4);    //将UART2从P1口切换到 RXD2--P1.2切换到P4.2   TXD2---P1.3切换到P4.3
    
    uart1_init();

    PrintString1("串口1测试程序");
    
    while(1)
    {
        display();
        detect_uart();
    }
}

void    UART1_TxByte(unsigned char dat)
{
    B_TI = 0;
    SBUF = dat;
    while(!B_TI);
    B_TI = 0;
    delay(10);
}


void PrintString1(unsigned char code *puts)        //发送一串字符串
{
    for (; *puts != 0;    puts++)  UART1_TxByte(*puts);     //遇到停止符0结束
}




void    uart1_init(void)
{
    PCON |= 0x80;        //UART0 Double Rate Enable
    SCON = 0x50;        //UART0 set as 10bit , UART0 RX enable
    TMOD &= ~(1<<6);        //Timer1 Set as Timer, 12T
    TMOD = (TMOD & ~0x30) | 0x20;    //Timer1 set as 8 bits auto relaod
    TH1 = T1_TimerReload;        //Load the timer
    TR1  = 1;
    ES  = 1;
    EA = 1;
}



/**********************************************/
void UART0_RCV (void) interrupt 4
{

    if(RI)
    {
        RI = 0;
        RX1_Buffer[uart1_wr] = SBUF;
        if(++uart1_wr >= BUF_LENTH)    uart1_wr = 0;
    }

    if(TI)
    {
        TI = 0;
        B_TI = 1;
    }
}

原文标题：MCU与FPGA串口通信

文章出处：【微信公众号：FPGA之家】欢迎添加关注！文章转载请注明出处。

审核编辑：彭菁

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