diff --git a/memory.hpp b/memory.hpp
index c462361..5f04fe0 100644
--- a/memory.hpp
+++ b/memory.hpp
@@ -1,3 +1,5 @@
+#pragma once
+
 namespace memory {
 
 template <typename T>
diff --git a/tools/ftdi_cbus.c b/tools/ftdi_cbus.c
new file mode 100644
index 0000000..bb10317
--- /dev/null
+++ b/tools/ftdi_cbus.c
@@ -0,0 +1,66 @@
+
+#include <stdio.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <ftdi.h>
+
+int main(void)
+{
+    struct ftdi_context *ftdi;
+    int f;
+    unsigned char buf[1];
+    unsigned char bitmask;
+    char input[10];
+
+    if ((ftdi = ftdi_new()) == 0)
+    {
+        fprintf(stderr, "ftdi_new failed\n");
+        return EXIT_FAILURE;
+    }
+
+    f = ftdi_usb_open(ftdi, 0x0403, 0x6014);
+    if (f < 0 && f != -5)
+    {
+        fprintf(stderr, "unable to open ftdi device: %d (%s)\n", f, ftdi_get_error_string(ftdi));
+        ftdi_free(ftdi);
+        exit(-1);
+    }
+    printf("ftdi open succeeded: %d\n",f);
+
+    while (1)
+    {
+        // Set bitmask from input
+        fgets(input, sizeof(input) - 1, stdin);
+        if (input[0] == '\n') break;
+        bitmask = strtol(input, NULL, 0);
+        printf("Using bitmask 0x%02x\n", bitmask);
+        f = ftdi_set_bitmode(ftdi, bitmask, BITMODE_CBUS);
+        if (f < 0)
+        {
+            fprintf(stderr, "set_bitmode failed for 0x%x, error %d (%s)\n", bitmask, f, ftdi_get_error_string(ftdi));
+            ftdi_usb_close(ftdi);
+            ftdi_free(ftdi);
+            exit(-1);
+        }
+
+        /*
+        // read CBUS
+        f = ftdi_read_pins(ftdi, &buf[0]);
+        if (f < 0)
+        {
+            fprintf(stderr, "read_pins failed, error %d (%s)\n", f, ftdi_get_error_string(ftdi));
+            ftdi_usb_close(ftdi);
+            ftdi_free(ftdi);
+            exit(-1);
+        }
+        printf("Read returned 0x%01x\n", buf[0] & 0x0f);
+        */
+    }
+    printf("disabling bitbang mode\n");
+    ftdi_disable_bitbang(ftdi);
+
+    ftdi_usb_close(ftdi);
+    ftdi_free(ftdi);
+
+    return 0;
+}