[feat] add uart demo

linux/main.c

@@ -0,0 +1,42 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <termios.h>
+#include <string.h>
+
+int main() {
+    int fd;
+    struct termios options;
+
+    // 打开 UART 设备文件
+    fd = open("/dev/ttyS3", O_RDWR | O_NOCTTY | O_NDELAY);
+    if (fd == -1) {
+        perror("open_port: Unable to open UART device");
+        return -1;
+    }
+
+    // 配置 UART 设备参数
+    tcgetattr(fd, &options);
+    options.c_cflag = B115200 | CS8 | CLOCAL | CREAD;
+    options.c_iflag = IGNPAR;
+    options.c_oflag = 0;
+    options.c_lflag = 0;
+    tcflush(fd, TCIFLUSH);
+    tcsetattr(fd, TCSANOW, &options);
+
+    // 读取和写入 UART 数据
+    char buf[128];
+    //memset(buf, 0x5A, sizeof(buf));
+    //write(fd, buf, 78);
+    //sleep(1);
+    int n = read(fd, buf, sizeof(buf));
+    if (n > 0) {
+        printf("Received data: %d, %s\n", n, buf);
+    }
+
+    write(fd, "Hello, UART!\n", 13);
+
+    close(fd);
+    return 0;
+}