diff --git a/CMakeLists.txt b/CMakeLists.txt
index 54102a7..877ae24 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -18,6 +18,7 @@ set(SOURCES
   src/gintctl.c
   src/menu.c
   src/plot.c
+  src/usb_commands.c
   src/util.c
   src/gint/cpumem.c
   src/gint/dma.c
diff --git a/include/gintctl/util.h b/include/gintctl/util.h
index 53c094d..fa3e486 100644
--- a/include/gintctl/util.h
+++ b/include/gintctl/util.h
@@ -8,6 +8,7 @@
 #include <stdarg.h>
 #include <stdint.h>
 #include <gint/keyboard.h>
+#include <gint/usb-ff-bulk.h>
 
 //---
 //	Platform disambiguation functions
@@ -94,6 +95,12 @@ void fkey_button(int position, char const *text);
 /* fkey_menu(): A rectangular F-key with the bottom right corner removed */
 void fkey_menu(int position, char const *text);
 
+//---
+// USB commands
+//---
+
+void gintctl_handle_usb_command(usb_fxlink_header_t const *header);
+
 #endif /* FXCG50 */
 
 #endif /* GINTCTL_UTIL */
diff --git a/src/gint/usb.c b/src/gint/usb.c
index b21a935..c700a3f 100644
--- a/src/gint/usb.c
+++ b/src/gint/usb.c
@@ -582,5 +582,6 @@ void gintctl_gint_usb(void)
 			alignment_write_tests(&awd);
 	}
 
+	usb_set_log(NULL);
 	global_interrupt_flag = NULL;
 }
diff --git a/src/gintctl.c b/src/gintctl.c
index 6316037..9747fc7 100644
--- a/src/gintctl.c
+++ b/src/gintctl.c
@@ -182,13 +182,8 @@ key_event_t gintctl_getkey_opt(int options)
 
 	while(1) {
 		key_event_t ev = getkey_opt(options, &gintctl_interrupt);
-
-		while(usb_fxlink_handle_messages(&header)) {
-			USB_LOG("[gintctl] dropping %.16s.%.16s\n",
-				header.application, header.type);
-			usb_fxlink_drop_transaction();
-			USB_LOG("[gintctl] done dropping\n");
-		}
+		while(usb_fxlink_handle_messages(&header))
+			gintctl_handle_usb_command(&header);
 
 		/* Keep waiting only if we were interrupted *and* the interrupt only
 		   set bit #31 */
diff --git a/src/usb_commands.c b/src/usb_commands.c
new file mode 100644
index 0000000..1045550
--- /dev/null
+++ b/src/usb_commands.c
@@ -0,0 +1,105 @@
+#include <gint/usb.h>
+#include <gint/usb-ff-bulk.h>
+#include <string.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <endian.h>
+#include <ctype.h>
+
+static void drop(usb_fxlink_header_t const *h)
+{
+    USB_LOG("[gintctl] dropping %.16s.%.16s\n", h->application, h->type);
+    usb_fxlink_drop_transaction();
+    USB_LOG("[gintctl] done dropping\n");
+}
+
+void gintctl_handle_usb_command(usb_fxlink_header_t const *h)
+{
+    if(strcmp(h->application, "gintctl") != 0)
+        return drop(h);
+
+    if(!strcmp(h->type, "echo-bounds")) {
+        int buffer[128], first = 0, last = 0, total = 0;
+        int block = USB_READ_BLOCK;
+
+        while(1) {
+            timeout_t tm = timeout_make_ms(1000);
+            int rc = usb_read_async(usb_ff_bulk_input(), buffer, sizeof buffer,
+                USB_READ_WAIT | block, NULL, &tm, GINT_CALL_NULL);
+            if(rc < 0)
+                break;
+            block = 0;
+
+            if(total == 0)
+                first = le32toh(buffer[0]);
+            if(rc >= 4)
+                last = le32toh(buffer[rc / 4 - 1]);
+            total += rc;
+
+            if(rc != sizeof buffer)
+                break;
+        }
+
+        char str[64];
+        sprintf(str, "first=%08x last=%08x total=%d B\n", first, last, total);
+        usb_fxlink_text(str, 0);
+        return;
+    }
+
+    if(!strcmp(h->type, "garbage")) {
+        /* Purposefully don't read the transaction's contents so they get
+           interpreted as garbage headers; this is to stress test the function
+           that reads & interprets headers. */
+        return;
+    }
+
+    if(!strcmp(h->type, "read-unaligned")) {
+        /* Read by little bits depending on given mode */
+        char mode;
+        usb_read_sync(usb_ff_bulk_input(), &mode, 1, false);
+
+        char *buf = malloc(h->size);
+        if(!buf) {
+            usb_fxlink_drop_transaction();
+            return;
+        }
+
+        USB_LOG("[gintctl] Read unaligned size %d mode '%c'\n",
+            h->size-1, mode);
+        if(mode == 'r')
+            srand(0xc0ffee);
+
+        size_t i = 0;
+        int round_number = 0;
+
+        while(i < h->size - 1) {
+            size_t round = 1;
+
+            /* Determine the size of this next round */
+            if(isdigit(mode)) {
+                round = mode - '0';
+            }
+            else if(mode == 'i') {
+                round = (round_number & 3) + 1;
+            }
+            else if(mode == 'r') {
+                round = rand() & 15;
+            }
+
+            if(round > (h->size - 1) - i)
+                round = h->size - 1 - i;
+            usb_read_sync(usb_ff_bulk_input(), buf + i, round, false);
+            i += round;
+            round_number++;
+        }
+
+        /* Echo the result */
+        buf[h->size - 1] = 0;
+        USB_LOG("Final result: %s\n", buf);
+        usb_fxlink_text(buf, h->size - 1);
+        free(buf);
+        return;
+    }
+
+    drop(h);
+}