ZYNQ linux下AXI_BRAM的使用方法，PS与PL端数据交互

1、AXI总线、AXI接口、AXI协议
总线是一组传输通道，是各种逻辑器件构成的传输数据的通道；接口是一种连接标准，又常被称为物理接口；协议是数据传输的规则。

PS与PL连接方式主要是通过AXI总线进行的。ZYNQ上的总线协议有AXI4, AXI4-Lite, AXI4-Stream三种总线协议。而PS与PL之间的接口（AXI-GP、AXI-HP、AXI-ACP）只支持AXI4与AXI4-Lite这两种总线协议。

2、BRAM简介
Block RAM是PL部分的存储器阵列，就相当于在PL中开辟一片空间来存储数据，通过端口来进行读写。
BRAM设置模式：
1、单端口：通过一个端口对BRAM进行读写。
2、简单双端口：有两个端口连接到BRAM，一个端口只读，一个端口只写
3、真双端口：两个端口都可以对BRAM进行读写。

3、vivado设计
前提：创建好了工程并导入了ZYNQ核

打开AXI GP0 和 AXI GP1的接口

将M_AXI_GP0_ACLK连接到FCLK_CLK0

导入两个BRAM 控制器

设置为单端口

导入一个BRAM

设置为真双端口模式

进行设计连接

进行1的时候需要修改主机从GP0 改为GP1

最终的生成图

可以在address editor中查看自动分配的BRAM控制器的地址，不要随意更改地址，因为其他地址可能被其他设备占用了。
axi_bram_ctrl_0 0x40000000
axi_bram_ctrl_1 0x80000000

接下来生成bit流，将硬件资源导入petlainux中，生成BOOT.BIN 和image.ub

将生成的BOOT.BIN和内核放到板子上，启动系统。

进行编程：

#include <stdio.h>
#include <unistd.h>
#include <sys/mman.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>#define BRAM_CTRL_0 0x40000000
#define BRAM_CTRL_1 0x80000000
#define DATA_LEN    10int main(int argc, char **argv)
{unsigned int *map_base0;unsigned int *map_base1;int fd = open("/dev/mem", O_RDWR | O_SYNC);if (fd < 0) {printf("can not open /dev/mem \n");return (-1);}   printf("/dev/mem is open \n");map_base0 = mmap(NULL, DATA_LEN * 4, PROT_READ | PROT_WRITE, MAP_SHARED, fd, BRAM_CTRL_0);map_base1 = mmap(NULL, DATA_LEN * 4, PROT_READ | PROT_WRITE, MAP_SHARED, fd, BRAM_CTRL_1);if (map_base0 == 0 || map_base1 == 0 ) { printf("NULL pointer\n");}   else {printf("mmap successful\n");}   unsigned long addr;unsigned int content;int i = 0;printf("\nwrite data to bram\n");for (i = 0; i < DATA_LEN; i++) {addr = (unsigned long)(map_base0 + i); content = i + 2;map_base0[i] = content;printf("%2dth data, address: 0x%lx data_write: 0x%x\t\t\n", i, addr, content);}   printf("\nread data from bram\n");for (i = 0; i< DATA_LEN; i++) {addr = (unsigned long)(map_base1 + i); content = map_base1[i];printf("%2dth data, address: 0x%lx data_read: 0x%x\t\t\n", i, addr, content);}   close(fd);munmap(map_base0, DATA_LEN);munmap(map_base1, DATA_LEN);return 0;
}

运行效果

也可以将BRAM与socket进行联合使用，将PC端的数据发到PS端，PS端放在PL端，PL端再发给PS端，PS端发回PC端。

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <string.h>
#include <fcntl.h>
#define PORT 3333#define BRAM_CTRL0 0x40000000
#define BRAM_CTRL1 0x80000000
#define DATA_LEN   100unsigned int *map_base0;
unsigned int *map_base1;void udp_server(int sockfd)
{socklen_t len;struct sockaddr_in server_addr;int n;int opt = 1;len = sizeof(server_addr);server_addr.sin_family = AF_INET;server_addr.sin_addr.s_addr = htonl(INADDR_ANY);server_addr.sin_port = htons(PORT);setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR, &opt, sizeof(opt));if (bind(sockfd, (struct sockaddr *)&server_addr, sizeof(server_addr)) < 0) {printf("can not bind\n");exit(1);}   while (1) {printf("\n========wait for client's request========\n");n = recvfrom(sockfd, map_base0, 1024, 0, (struct sockaddr *)&server_addr, &len);char buf[1024];memcpy(buf, map_base0, 1024);printf("\nreceive client's data: %s\n", buf);sendto(sockfd, map_base0, n, 0, (struct sockaddr *)&server_addr, len);memcpy(buf, map_base1, 1024);printf("\nsend data to client: %s\n", buf);}close(sockfd);
}int main(int argc, char **argv)
{int sockfd, devfd;if ((sockfd = socket(PF_INET, SOCK_DGRAM, 0)) < 0) {printf("create socket false\n");exit(1);}if ((devfd = open("/dev/mem", O_RDWR | O_SYNC)) < 0) {printf("can not open /dev/mem \n");return (-1);}printf("\nopen /dev/mem successful\n");map_base0 = mmap(NULL, DATA_LEN * 4, PROT_READ | PROT_WRITE, MAP_SHARED, devfd, BRAM_CTRL0);map_base1 = mmap(NULL, DATA_LEN * 4, PROT_READ | PROT_WRITE, MAP_SHARED, devfd, BRAM_CTRL1);if (map_base0 ==0 || map_base1 == 0) {printf("NULL pointer \n");}else {printf("mmap successful\n");}udp_server(sockfd);exit(0);
}

最终实现相关效果