这里用一个串口接收PC机传过来的读写寄存器的控制指令，对地址地址的AXI_sLAVE进行读写后返回其结果。
串口收发器用的代码还是经典的FPGA4FUN上的。fpga4fun.com - Serial interface (RS-232)
我做了极小修改，直接贴出来代码：
// RS-232 RX and TX module
// (c) fpga4fun.com & KNJN LLC - 2003 to 2016// The RS-232 settings are fixed
// TX: 8-bit data, 2 stop, no-parity
// RX: 8-bit data, 1 stop, no-parity (the receiver can accept more stop bits of course)//`define SIMULATION // in this mode, TX outputs one bit per clock cycle// and RX receives one bit per clock cycle (for fast simulations)module async_transmitter(input clk,input TxD_start,input [7:0] TxD_data,output TxD,output TxD_busy
);// Assert TxD_start for (at least) one clock cycle to start transmission of TxD_data
// TxD_data is latched so that it doesn't have to stay valid while it is being sentparameter ClkFrequency = 1000*1000*100; // 100MHz
parameter Baud = 115200;generateif(ClkFrequency<Baud*8 && (ClkFrequency % Baud!=0)) ASSERTION_ERROR PARAMETER_OUT_OF_RANGE("Frequency incompatible with requested Baud rate");
endgenerate`ifdef SIMULATION
wire BitTick = 1'b1; // output one bit per clock cycle
`else
wire BitTick;
BaudTickGen #(ClkFrequency, Baud) tickgen(.clk(clk), .enable(TxD_busy), .tick(BitTick));
`endifreg [3:0] TxD_state = 0;
wire TxD_ready = (TxD_state==0);
assign TxD_busy = ~TxD_ready;reg [7:0] TxD_shift = 0;
always @(posedge clk)
beginif(TxD_ready & TxD_start)TxD_shift <= TxD_data;elseif(TxD_state[3] & BitTick)TxD_shift <= (TxD_shift >> 1);case(TxD_state)4'b0000: if(TxD_start) TxD_state <= 4'b0100;4'b0100: if(BitTick) TxD_state <= 4'b1000; // start bit4'b1000: if(BitTick) TxD_state <= 4'b1001; // bit 04'b1001: if(BitTick) TxD_state <= 4'b1010; // bit 14'b1010: if(BitTick) TxD_state <= 4'b1011; // bit 24'b1011: if(BitTick) TxD_state <= 4'b1100; // bit 34'b1100: if(BitTick) TxD_state <= 4'b1101; // bit 44'b1101: if(BitTick) TxD_state <= 4'b1110; // bit 54'b1110: if(BitTick) TxD_state <= 4'b1111; // bit 64'b1111: if(BitTick) TxD_state <= 4'b0010; // bit 74'b0010: if(BitTick) TxD_state <= 4'b0011; // stop14'b0011: if(BitTick) TxD_state <= 4'b0000; // stop2default: if(BitTick) TxD_state <= 4'b0000;endcase
endassign TxD = (TxD_state<4) | (TxD_state[3] & TxD_shift[0]); // put together the start, data and stop bits
endmodulemodule async_receiver(input clk,input RxD,output reg RxD_data_ready = 0,output reg [7:0] RxD_data = 0, // data received, valid only (for one clock cycle) when RxD_data_ready is asserted// We also detect if a gap occurs in the received stream of characters// That can be useful if multiple characters are sent in burst// so that multiple characters can be treated as a "packet"output RxD_idle, // asserted when no data has been received for a whileoutput reg RxD_endofpacket = 0 // asserted for one clock cycle when a packet has been detected (i.e. RxD_idle is going high)
);parameter ClkFrequency = 1000*1000*100; // 100MHz
parameter Baud = 115200;parameter Oversampling = 8; // needs to be a power of 2
// we oversample the RxD line at a fixed rate to capture each RxD data bit at the "right" time
// 8 times oversampling by default, use 16 for higher quality receptiongenerateif(ClkFrequency<Baud*Oversampling) ASSERTION_ERROR PARAMETER_OUT_OF_RANGE("Frequency too low for current Baud rate and oversampling");if(Oversampling<8 || ((Oversampling & (Oversampling-1))!=0)) ASSERTION_ERROR PARAMETER_OUT_OF_RANGE("Invalid oversampling value");
endgeneratereg [3:0] RxD_state = 0;`ifdef SIMULATION
wire RxD_bit = RxD;
wire sampleNow = 1'b1; // receive one bit per clock cycle`else
wire OversamplingTick;
BaudTickGen #(ClkFrequency, Baud, Oversampling) tickgen(.clk(clk), .enable(1'b1), .tick(OversamplingTick));// synchronize RxD to our clk domain
reg [1:0] RxD_sync = 2'b11;
always @(posedge clk) if(OversamplingTick) RxD_sync <= {RxD_sync[0], RxD};// and filter it
reg [1:0] Filter_cnt = 2'b11;
reg RxD_bit = 1'b1;always @(posedge clk)
if(OversamplingTick)
beginif(RxD_sync[1]==1'b1 && Filter_cnt!=2'b11) Filter_cnt <= Filter_cnt + 1'd1;else if(RxD_sync[1]==1'b0 && Filter_cnt!=2'b00) Filter_cnt <= Filter_cnt - 1'd1;if(Filter_cnt==2'b11) RxD_bit <= 1'b1;elseif(Filter_cnt==2'b00) RxD_bit <= 1'b0;
end// and decide when is the good time to sample the RxD line
function integer log2(input integer v); begin log2=0; while(v>>log2) log2=log2+1; end endfunction
localparam l2o = log2(Oversampling);
reg [l2o-2:0] OversamplingCnt = 0;
always @(posedge clk) if(OversamplingTick) OversamplingCnt <= (RxD_state==0) ? 1'd0 : OversamplingCnt + 1'd1;
wire sampleNow = OversamplingTick && (OversamplingCnt==Oversampling/2-1);
`endif// now we can accumulate the RxD bits in a shift-register
always @(posedge clk)
case(RxD_state)4'b0000: if(~RxD_bit) RxD_state <= `ifdef SIMULATION 4'b1000 `else 4'b0001 `endif; // start bit found?4'b0001: if(sampleNow) RxD_state <= 4'b1000; // sync start bit to sampleNow4'b1000: if(sampleNow) RxD_state <= 4'b1001; // bit 04'b1001: if(sampleNow) RxD_state <= 4'b1010; // bit 14'b1010: if(sampleNow) RxD_state <= 4'b1011; // bit 24'b1011: if(sampleNow) RxD_state <= 4'b1100; // bit 34'b1100: if(sampleNow) RxD_state <= 4'b1101; // bit 44'b1101: if(sampleNow) RxD_state <= 4'b1110; // bit 54'b1110: if(sampleNow) RxD_state <= 4'b1111; // bit 64'b1111: if(sampleNow) RxD_state <= 4'b0010; // bit 74'b0010: if(sampleNow) RxD_state <= 4'b0000; // stop bitdefault: RxD_state <= 4'b0000;
endcasealways @(posedge clk)
if(sampleNow && RxD_state[3]) RxD_data <= {RxD_bit, RxD_data[7:1]};//reg RxD_data_error = 0;
always @(posedge clk)
beginRxD_data_ready <= (sampleNow && RxD_state==4'b0010 && RxD_bit); // make sure a stop bit is received//RxD_data_error <= (sampleNow && RxD_state==4'b0010 && ~RxD_bit); // error if a stop bit is not received
end`ifdef SIMULATION
assign RxD_idle = 0;
`else
reg [l2o+1:0] GapCnt = 0;
always @(posedge clk) if (RxD_state!=0) GapCnt<=0; else if(OversamplingTick & ~GapCnt[log2(Oversampling)+1]) GapCnt <= GapCnt + 1'h1;
assign RxD_idle = GapCnt[l2o+1];
always @(posedge clk) RxD_endofpacket <= OversamplingTick & ~GapCnt[l2o+1] & &GapCnt[l2o:0];
`endifendmodule// dummy module used to be able to raise an assertion in Verilog
module ASSERTION_ERROR();
endmodulemodule BaudTickGen(input clk, enable,output tick // generate a tick at the specified baud rate * oversampling
);
parameter ClkFrequency = 25000000;
parameter Baud = 115200;
parameter Oversampling = 1;function integer log2(input integer v); begin log2=0; while(v>>log2) log2=log2+1; end endfunction
localparam AccWidth = log2(ClkFrequency/Baud)+8; // +/- 2% max timing error over a byte
reg [AccWidth:0] Acc = 0;
localparam ShiftLimiter = log2(Baud*Oversampling >> (31-AccWidth)); // this makes sure Inc calculation doesn't overflow
localparam Inc = ((Baud*Oversampling << (AccWidth-ShiftLimiter))+(ClkFrequency>>(ShiftLimiter+1)))/(ClkFrequency>>ShiftLimiter);
always @(posedge clk) if(enable) Acc <= Acc[AccWidth-1:0] + Inc[AccWidth:0]; else Acc <= Inc[AccWidth:0];
assign tick = Acc[AccWidth];
endmodule我写的代码就是下面的这个状态机：
/*uart2bus32 uart2bus32(
.clk( ) ,
.rst( ) ,.uart_in_u8( ) ,
.uart_in_valid( ) ,.uart_out_u8( ) ,
.uart_out_valid( ) ,
.uart_out_busy( ) ,.addr ( ) ,
.wr_u32( ) ,
.wr_vaild( ) ,
.wr_ready( ) ,
.wr_err( ) ,.rd_addr_valid ( ) ,
.rd_done ( ) ,
.rd_err( ) ,
.rd_u32 ( )
);*/module uart2bus32(
input clk,rst,input [7:0] uart_in_u8,
input uart_in_valid,output reg [31:0] uart_out_u8,
output reg uart_out_valid,
input uart_out_busy,output reg [31:0] addr ,
output reg [31:0] wr_u32,
output reg wr_vaild,
input wr_ready,wr_err,output reg rd_addr_valid ,
input rd_done ,rd_err,
input[31:0] rd_u32 ,
output reg [7:0] st
);reg wr_err_r ; always@(posedge clk) if (wr_ready)wr_err_r <= wr_err ; function [7:0] chksum_u32;input [31:0] u ;begin chksum_u32 = u[31:24] + u[23:16] +u[15:8] + u[7:0] ; end endfunction reg [7:0]addr_chksum ;
reg [3:0] c;
reg [7:0] delay ;
reg [31:0]rd_u32_r;
reg [7:0] rd_u32_chksum;always @(posedge clk) addr_chksum <=chksum_u32( addr);
reg [7:0] wr_u32_chksum ;always@(posedge clk )wr_u32_chksum <= chksum_u32(wr_u32) + addr_chksum ;always @(posedge clk) case (st) 44:delay <= delay+1;default delay<=0;endcase
reg [7:0] cmd ; always@(posedge clk) if (st==12) cmd<=uart_in_u8 ; always @(posedge clk) if (rst) st<=5;else case(st)
0 : st <= 5 ;
5 : st <= 10 ;
10 : if (uart_in_valid) st<= (uart_in_u8 == 'h55 ) ?(st+1): 10;
11 : if (uart_in_valid) st<= (uart_in_u8 == 'haa ) ?(st+1): 10;
12 : if (uart_in_valid) case (uart_in_u8)3,5:st<=30;default st<=10;endcase 30,31,32,33:if (uart_in_valid) st<= st+1;
34:if (cmd ==3 ) st<=st+1;else st<=50;
35:if (uart_in_valid) st<=( addr_chksum == uart_in_u8 ) ? 40: 10;
40:st<=st+1;// read function
41:if ( rd_done ) st<=st+1;
42:if (uart_out_busy==0) st<=st+1;
43:st<=st+1; // do write
44:if (delay==10) st<=st+1;
45:st<=st+1;
46:if (c!=5) st<=42;else st<=st+1;//c++
47:st<=st+1;
48:st<= 10; 50,51,52,53:if (uart_in_valid) st<=st+1;
54: if(uart_in_valid) st<=(wr_u32_chksum==uart_in_u8) ? 55 : 1059;
55: st<=st+1;// set as valid
56: if ( wr_ready ) st<=st+1;
57: st<=st+1;
58: if ( uart_out_busy ==0) st<=st+1;
59: st<=10;default st<=0;endcase always @(*) wr_vaild = st== 55 ;
always @(posedge clk) if (st==30) addr[31:24] <= uart_in_u8;
always @(posedge clk) if (st==31) addr[23:16] <= uart_in_u8;
always @(posedge clk) if (st==32) addr[15:8] <= uart_in_u8;
always @(posedge clk) if (st==33) addr[7:0] <= uart_in_u8;always @(posedge clk) if (st==50) wr_u32[31:24] <= uart_in_u8;
always @(posedge clk) if (st==51) wr_u32[23:16] <= uart_in_u8;
always @(posedge clk) if (st==52) wr_u32[15:8] <= uart_in_u8;
always @(posedge clk) if (st==53) wr_u32[7:0] <= uart_in_u8;always @(*)rd_addr_valid= st==40 ;always @(posedge clk) if ( rd_done )rd_u32_r <= rd_u32 ;
reg rd_err_r ; always @(posedge clk) if ( rd_done)rd_err_r <= rd_err ;always @(posedge clk)rd_u32_chksum <=chksum_u32( rd_u32_r) + {7'b0,rd_err_r};
always @(posedge clk)case (st) 40:c<=0;46:c<=c+1;default c<=c;endcase
always @(posedge clk)uart_out_valid <= (st==43)||(st==59) ;always @(posedge clk)if (st==43)case (c)
0 : uart_out_u8 <= rd_u32_r [31:24] ;
1 : uart_out_u8 <= rd_u32_r [23:16] ;
2 : uart_out_u8 <= rd_u32_r [15:8] ;
3 : uart_out_u8 <= rd_u32_r [7:0] ;
5 : uart_out_u8 <= rd_u32_chksum ;
4 : uart_out_u8 <= {7'b0,rd_err_r};
endcase else if (st==59) uart_out_u8<={7'b0,wr_err_r}; else uart_out_u8 <= 0 ;endmodule 这个代码还是实现了CHECKSUM校验。
对应的PC端代码如下：
#include <stdio.h>
#include <string.h>
#include <sys/types.h>
#include <errno.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <termios.h>
#include <stdlib.h>
#include<sys/stat.h>
#include<fcntl.h>
#include<errno.h>
#include<netdb.h>
#include<sys/types.h>
#include<sys/socket.h>
#include<netinet/in.h>
#include<arpa/inet.h>
#include<string.h>
#include<stdlib.h>
#include<stdio.h>
#include<unistd.h>
#include<stdarg.h>
#include <sys/select.h>
#include <sys/time.h>void sdrpi_dev_init(int port ){int r = serial_open(port ,115200);
if (r<0){
printf("can not open serial,so exit \n");
exit(-1);
}
}static unsigned char get_byte(unsigned int u,int idx){
unsigned char r0,r1,r2,r3 ;
r0=u&0xff; u>>=8;
r1=u&0xff; u>>=8;
r2=u&0xff; u>>=8;
r3=u&0xff;if (idx==0)return r0;else
if (idx==1)return r1;else
if (idx==2)return r2;else
if (idx==3)return r3;
}unsigned int uart2master_wr(unsigned int addr ,unsigned int dat){
static unsigned char buff[20] ={0};
unsigned int sum = 0 ;
unsigned int r ;
int i ;
for(i=0;i<20;++i)buff[i]=0;
serial_write(buff,12);
buff[0]=0x55;
buff[1]=0xaa;
buff[2]=0x05; // write command buff[3]=get_byte(addr,3);
buff[4]=get_byte(addr,2);
buff[5]=get_byte(addr,1);
buff[6]=get_byte(addr,0);buff[7] =get_byte(dat,3);
buff[8] =get_byte(dat,2);
buff[9] =get_byte(dat,1);
buff[10]=get_byte(dat,0);for(sum=0,i=3;i<=10;++i) sum += buff[i] ;
buff[11]=sum &0xff;
serial_write(buff,12);
buff[0] = serial_try_getc(&i);if (i==0) { printf("wr: can not read serial,so exit \n");exit(-1); }
r = buff[0] ;
return r ; } checked OKunsigned int uart2master_rd(unsigned int addr ){static unsigned char buff[20];
unsigned char sum = 0 ;
unsigned int r ;
int i ;
buff[0]=0x55;
buff[1]=0xaa;
buff[2]=0x03; // read command buff[3]=get_byte(addr,3);
buff[4]=get_byte(addr,2);
buff[5]=get_byte(addr,1);
buff[6]=get_byte(addr,0);for(sum=0,i=3;i<=6;++i) sum+=buff[i];
buff[7]=sum&0xff ;serial_write(buff,8);buff[0] = serial_try_getc(&i); if ( i == 0 ) { printf("1 can not read serial,so exit \n");exit(-1); } ;//[31:24]
buff[1] = serial_try_getc(&i); if ( i == 0 ) { printf("2 can not read serial,so exit \n");exit(-1); } ;//[23:16]
buff[2] = serial_try_getc(&i); if ( i == 0 ) { printf("3 can not read serial,so exit \n");exit(-1); } ;//[15:8]
buff[3] = serial_try_getc(&i); if ( i == 0 ) { printf("3 can not read serial,so exit \n");exit(-1); } ;//[7:0]
buff[4] = serial_try_getc(&i); if ( i == 0 ) { printf("4 can not read serial,so exit \n");exit(-1); } ;//ERROR
buff[5] = serial_try_getc(&i); if ( i == 0 ) { printf("5 can not read serial,so exit \n");exit(-1); } ;//CHKSUMfor(sum=0,i=0;i<=4;++i) sum+=buff[i];if ( buff[5] != sum ) { printf("uart2master_rd check sum error local sum is %02x %02x \n",buff[5],sum &0xff); exit(-1);}
if (buff[4])printf("err bit is %d \n",buff[4]);r = buff[0] ; r <<= 8 ;
r |= buff[1] ; r <<= 8 ;
r |= buff[2] ; r <<= 8 ;
r |= buff[3] ; return r ; }void test_reg_loop (unsigned int addr ,unsigned int c){
unsigned int r ,t;
sdrpi_dev_init(0);
t = 0xabcdef01 ;
while(c--) {
t++;
uart2master_wr(addr,t);
r = uart2master_rd(addr);
printf("r = %08X\n",r);
if ( t != r){ printf("1 %08X %08X \n",t,r);exit(-1);}
}
printf("test_reg_loop test passed. \n");
}这里也同时贴出来LINUX下串口操作的代码：
#include <stdio.h>#include <string.h>#include <sys/types.h>#include <errno.h>#include <sys/stat.h>#include <fcntl.h>#include <unistd.h>#include <termios.h>#include <stdlib.h>#include<sys/stat.h>#include<fcntl.h>#include<errno.h>#include<netdb.h>#include<sys/types.h>#include<sys/socket.h>#include<netinet/in.h>#include<arpa/inet.h>#include<string.h>#include<stdlib.h>#include<stdio.h>#include<unistd.h>#include<stdarg.h>#include <sys/select.h>#include <sys/time.h>static int fd;static int set_opt( int nSpeed, int nBits, char nEvent, int nStop){struct termios newtio,oldtio;if ( tcgetattr( fd,&oldtio) != 0) { perror("SetupSerial 1");return -1;}bzero( &newtio, sizeof( newtio ) );newtio.c_cflag |= CLOCAL | CREAD; newtio.c_cflag &= ~CSIZE; switch( nBits ){case 7:newtio.c_cflag |= CS7;break;case 8:newtio.c_cflag |= CS8;break;}switch( nEvent ){case 'O': //奇校验newtio.c_cflag |= PARENB;newtio.c_cflag |= PARODD;newtio.c_iflag |= (INPCK | ISTRIP);break;case 'E': //偶校验newtio.c_iflag |= (INPCK | ISTRIP);newtio.c_cflag |= PARENB;newtio.c_cflag &= ~PARODD;break;case 'N': //无校验newtio.c_cflag &= ~PARENB;break;}switch( nSpeed ){case 2400:cfsetispeed(&newtio, B2400);cfsetospeed(&newtio, B2400);break;case 4800:cfsetispeed(&newtio, B4800);cfsetospeed(&newtio, B4800);break;case 9600:cfsetispeed(&newtio, B9600);cfsetospeed(&newtio, B9600);break;case 115200:cfsetispeed(&newtio, B115200);cfsetospeed(&newtio, B115200);break;default:cfsetispeed(&newtio, B9600);cfsetospeed(&newtio, B9600);break;}if( nStop == 1 ){newtio.c_cflag &= ~CSTOPB;}else if ( nStop == 2 ){newtio.c_cflag |= CSTOPB;}newtio.c_cc[VTIME] = 0;newtio.c_cc[VMIN] = 0;tcflush(fd,TCIFLUSH);if((tcsetattr(fd,TCSANOW,&newtio))!=0){perror("com set error");return -1;}printf("set done!\n");return 0;}static int open_port( int comport){long vdisable;char port_name[100] ;sprintf(port_name,"/dev/ttyUSB%d",comport);// fd = open( "/dev/ttyUSB0", O_RDWR);fd = open( port_name, O_RDWR|O_NOCTTY |O_NDELAY);if (-1 == fd){perror("Can't Open Serial Port");return(-1);}else {printf("open ttyUSB0 .....\n");}if(fcntl(fd, F_SETFL, 0)<0){printf("fcntl failed!\n");}else{printf("fcntl=%d\n",fcntl(fd, F_SETFL,0));}if(isatty(STDIN_FILENO)==0){printf("standard input is not a terminal device\n");}else{printf("isatty success!\n");}printf("fd-open=%d\n",fd);return fd;}int serial_open (int i ,unsigned int baund ){if((fd=open_port(i))<0){perror("open_port error");return -1;}if((i=set_opt(baund,8,'N',2))<0){perror("set_opt error");return -1 ;}printf("fd=%d\n",fd);return 0 ;}int serial_write(char * buf , int len ){return write(fd,buf,len);}static int is_serial_ready(int fd){/*利用SELECT监视端口数据就可以fd_set fds;timeval timeout={3,0}; //select等待3秒FD_ZERO(&fds); //每次循环都要清空集合，否则不能检测描述符变化FD_SET(m_CSocket,&fds); //添加描述符int sel=select(m_CSocket+1,&fds,NULL,NULL,&timeout);在等待的timeout时间内，若端口有数据，则select函数会返回，通过判断sel的值，就知道端口是否有数据，或者是超时了。*/int rc ;fd_set fds ;struct timeval tv ;//printf("enter is_ready %d\n",cnt++);tv.tv_sec=3 ;tv.tv_usec=2;FD_ZERO(&fds);FD_SET(fd,&fds);rc=select(fd+1,&fds,NULL,NULL,&tv);//printf("out is ready res =%d \n",rc);if(rc<0)return -1 ;rc=FD_ISSET(fd,&fds)?1:0 ;//printf(" result is =%d \n",rc);return rc ;
}static char serial_getchar(){
char ch ;
while(read(fd,&ch ,1)==0); return ch ;
}static int serial_read(char * buf,int len ){
int i;
for(i=0;i<len;++i)buf[i] = serial_getchar() ;
return len;
}unsigned char serial_try_getc (int *valid ){*valid=0;
if (is_serial_ready(fd)==0) return 0XFF ;
*valid=1;
return serial_getchar();
}int serial_putc(char c){static char buf[2];buf[0]=c; return write(fd,buf,1);}
