Example program of using USB mass storage device (USB flash disk) with STM32F407VET6 boards (compatible with Seed Arch Max). This is a fork of https://os.mbed.com/users/va009039/code/F401RE-USBHostMSD_HelloWorld/

Dependencies:   mbed FATFileSystem USBHost-STM32F4

Revision:
0:4ea663e6aa00
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp	Tue Feb 19 21:35:40 2019 +0000
@@ -0,0 +1,51 @@
+#include "USBHostMSD.h"
+
+DigitalOut  led1(LED1);
+
+int main()
+{
+    printf("Starting..\r\n");
+
+    USBHostMSD  msd("usb");
+    
+    printf("Connecting the device\r\n");
+    
+    if (!msd.connect()) {
+        error("USB mass storage device not found.\n");
+    }
+    
+    FILE*   fp = fopen("/usb/test1.txt", "a");
+    if (fp) {
+        fprintf(fp, "Hello from mbed.\n");
+        for (int i = 0; i < 21; i++) {
+            fprintf(fp, " %d", i);
+            led1 = !led1;
+        }
+
+        fprintf(fp, "\n");
+        fclose(fp);
+    }
+
+    fp = fopen("/usb/test1.txt", "r");
+    if (fp) {
+        int n = 0;
+        while (1) {
+            int c = fgetc(fp);
+            if (c == EOF) {
+                break;
+            }
+
+            printf("%c", c);
+            n++;
+            led1 = !led1;
+        }
+
+        fclose(fp);
+        printf("%d bytes\n", n);
+    }
+
+    while (1) {
+        led1 = !led1;
+        wait_ms(200);
+    }
+}