diff --git a/USB/README.TXT b/USB/README.TXT
new file mode 100644
index 0000000..7557052
--- /dev/null
+++ b/USB/README.TXT
@@ -0,0 +1,19 @@
+USB support is implemented using the STM32 USB Device library.
+
+The library is copied into the core project to make customizations easier to maintain
+across different ports. The USBD library supports all versions of the HAL and LL.
+
+GEX uses USB classes CDC/ACM and MSC/SCSI.
+The two classes are combined into a composite class with association descriptors.
+
+USB interrupts are processed by the USBD library and endpoint callbacks in the composite
+class are fired. To avoid race conditions (and because DAPlink did it the same way), the
+events are notified to the USB thread (TaskMain) which calls endpoint handlers in the
+corresponding class drivers.
+
+VFS is handled synchronously on the main thread. CDC messages (TinyFrame data) are queued
+and processed by the message queue thread. This makes it possible to query hardware
+(e.g. slow USART or NeoPixel) without stalling the USB communication. This arrangement
+also makes it possible to wait on a binary semaphore when sending data back to host. The
+semaphore is set from the CDC TxComplete callback and taken by the TinyFrame write
+function, serving as a form of flow control.
diff --git a/cortex_handlers.c b/cortex_handlers.c
index 6e5584d..37ebfd8 100644
--- a/cortex_handlers.c
+++ b/cortex_handlers.c
@@ -1,3 +1,8 @@
+//
+// Some FreeRTOS / CortexM callbacks are implemented here
+// (moved from the top level project for easier maintenance)
+//
+
 /* Includes ------------------------------------------------------------------*/
 
 #include "platform.h"
diff --git a/debug.h b/debug.h
index 65ec0fd..c6b1c8e 100644
--- a/debug.h
+++ b/debug.h
@@ -1,6 +1,8 @@
 //
 // Created by MightyPork on 2017/11/04.
 //
+// Debugging functions
+//
 
 #ifndef GEX_DEBUG_H
 #define GEX_DEBUG_H
@@ -12,12 +14,19 @@
 
 #if USE_DEBUG_UART
 
+/** Externally defined function for writing to the debug UART */
 extern void debug_write(const char *buf, uint16_t len);
 
+/** Debug printf, used in the macros below */
 void _DO_PRINTF(const char *format, ...) __attribute__((format(printf,1,2))) ;
+
+/** putsn to debug */
 void PUTSN(const char *string, uint16_t len);
+
+/** puts to debug */
 void PUTS(const char *string);
 
+/** puts with just a newline */
 static inline void PUTNL(void)
 {
     debug_write("\r\n", 2);
@@ -33,6 +42,12 @@ static inline void PUTCHAR(char ch)
     debug_write(&ch, 1);
 }
 
+// NOTE: Those macros use puts instead of printf if the format is the only arg.
+// this saves ROM and stack overhead
+
+/**
+ * Debug printf
+ */
 #define PRINTF(format, ...) do { \
     if (VA_ARG_COUNT(__VA_ARGS__) == 0) { \
       PUTS(format); \
@@ -41,6 +56,9 @@ static inline void PUTCHAR(char ch)
     } \
   } while (0)
 
+/**
+ * Debug printf (with a newline)
+ */
 #define dbg(format, ...) do { \
     if (VA_ARG_COUNT(__VA_ARGS__) == 0) { \
       PUTS(format); \
@@ -50,14 +68,13 @@ static inline void PUTCHAR(char ch)
     PUTNL(); \
   } while (0)
 
-
 #else
-#define dbg(format, ...) do {} while (0)
-#define PRINTF(format, ...) do {} while (0)
-#define PUTSN(string, len) do {} while (0)
-#define PUTS(string) do {} while (0)
-#define PUTNL() do {} while (0)
-#define PUTCHAR(ch) do {} while (0)
+    #define dbg(format, ...) do {} while (0)
+    #define PRINTF(format, ...) do {} while (0)
+    #define PUTSN(string, len) do {} while (0)
+    #define PUTS(string) do {} while (0)
+    #define PUTNL() do {} while (0)
+    #define PUTCHAR(ch) do {} while (0)
 #endif
 
 #endif //GEX_DEBUG_H
diff --git a/freertos.c b/freertos.c
index 24116d4..b19b04a 100644
--- a/freertos.c
+++ b/freertos.c
@@ -1,3 +1,7 @@
+//
+// FreeRTOS setup
+//
+
 /**
   ******************************************************************************
   * File Name          : freertos.c
diff --git a/gex_hooks.h b/gex_hooks.h
index 20a1362..8419fd0 100644
--- a/gex_hooks.h
+++ b/gex_hooks.h
@@ -1,6 +1,8 @@
 //
 // Created by MightyPork on 2017/12/15.
 //
+// Callbacks from the top level main() function etc
+//
 
 #ifndef GEX_GEX_HOOKS_H
 #define GEX_GEX_HOOKS_H
diff --git a/stm32_assert.h b/stm32_assert.h
index f3c9e09..22985a9 100644
--- a/stm32_assert.h
+++ b/stm32_assert.h
@@ -1,6 +1,8 @@
 //
 // Created by MightyPork on 2017/11/20.
 //
+// Assert handling with traps
+//
 
 #ifndef STM32_ASSERT_H
 #define STM32_ASSERT_H
diff --git a/utils/avrlibc.h b/utils/avrlibc.h
index 16a8770..683d8b5 100644
--- a/utils/avrlibc.h
+++ b/utils/avrlibc.h
@@ -1,14 +1,59 @@
 //
 // Created by MightyPork on 2017/11/26.
 //
+// Those are low memory footprint implementations of some stdlib functions
+// taken from the AVR libc. They are used instead of newlib versions.
+//
 
 #ifndef GEX_AVRLIBC_H_H
 #define GEX_AVRLIBC_H_H
 
+/**
+ * atoi() - parse decimal int from ASCII
+ *
+ * @param p - string
+ * @return int, 0 on failure
+ */
 int avr_atoi(const char *p);
-long avr_strtol(const char *nptr, char **endptr, register int base);
+
+/**
+ * atol() - parse decimal long int from ASCII
+ *
+ * @param p - string
+ * @return int, 0 on failure
+ */
 long avr_atol(const char *p);
+
+/**
+ * strtol() - parse integer number form string.
+ * this is internally called by atol and atoi
+ *
+ * 0x is allowed for bases 0 and 16
+ *
+ * @param nptr - string to parse
+ * @param endptr - NULL or pointer to string where the end will be stored (first bad char)
+ * @param base - base 2, 10, 16.... 0 for auto
+ * @return the number
+ */
+long avr_strtol(const char *nptr, char **endptr, register int base);
+
+/**
+ * Parse double from ASCII
+ *
+ * @param nptr - string to parse
+ * @param endptr - NULL or pointer to string where the end will be stored (first bad char)
+ * @return  the number
+ */
 double avr_strtod (const char * nptr, char ** endptr);
+
+/**
+ * like strtol(), but unsigned (and hence higher max value)
+ *
+ * @param nptr - string to parse
+ * @param endptr - NULL or pointer to string where the end will be stored (first bad char)
+ * @param base - base 2, 10, 16.... 0 for auto
+ * @return the number
+ */
 unsigned long avr_strtoul(const char *nptr, char **endptr, register int base);
 
 #endif //GEX_AVRLIBC_H_H
diff --git a/utils/circ_buf.h b/utils/circ_buf.h
index a293e5d..69e5fcd 100644
--- a/utils/circ_buf.h
+++ b/utils/circ_buf.h
@@ -1,3 +1,7 @@
+//
+// This is a circular buffer implementation borrowed from the DAPLink firmware
+//
+
 /**
  * @file    circ_buf.h
  * @brief   Implementation of a circular buffer
diff --git a/utils/cortex_utils.h b/utils/cortex_utils.h
index d52cc7a..6cb114a 100644
--- a/utils/cortex_utils.h
+++ b/utils/cortex_utils.h
@@ -1,6 +1,8 @@
 //
 // Created by MightyPork on 2017/11/26.
 //
+// Cortex-M utilities (low level stuff missing from CMSIS)
+//
 
 #ifndef GEX_CORTEX_UTILS_H
 #define GEX_CORTEX_UTILS_H
diff --git a/utils/error.h b/utils/error.h
index 7c624be..b5d64a8 100644
--- a/utils/error.h
+++ b/utils/error.h
@@ -1,23 +1,6 @@
-/**
- * @file    error.h
- * @brief   collection of known errors and accessor for the friendly string
- *
- * DAPLink Interface Firmware
- * Copyright (c) 2009-2016, ARM Limited, All Rights Reserved
- * SPDX-License-Identifier: Apache-2.0
- *
- * Licensed under the Apache License, Version 2.0 (the "License"); you may
- * not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- * http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
- * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
+//
+// Error codes and labels. Loosely based on DAPLink, with more codes added.
+//
 
 #ifndef ERROR_H
 #define ERROR_H
@@ -59,7 +42,10 @@
     X(OUT_OF_MEM, "Not enough RAM") \
     X(RESOURCE_NOT_AVAILABLE, NULL)
 
-// Keep in sync with the list error_message
+
+/**
+ * The return value for all functions with error reporting.
+ */
 typedef enum {
 #define X(name, text) E_##name,
     X_ERROR_CODES
@@ -67,8 +53,6 @@ typedef enum {
     ERROR_COUNT
 } error_t;
 
-const char *error_get_message(error_t error) __attribute__((pure));
-const char *error_get_name(error_t error) __attribute__((pure));
 
 /** Check return value and return it if not E_SUCCESS */
 #define TRY(call) do { \
@@ -77,6 +61,24 @@ const char *error_get_name(error_t error) __attribute__((pure));
     if (E_SUCCESS != _rv) return _rv; \
 } while (0)
 
+
+/**
+ * Get a user-friendly message from a E_* enum value
+ *
+ * @param error - E_* value
+ * @return string, error name or description
+ */
+const char *error_get_message(error_t error) __attribute__((pure));
+
+
+/**
+ * Get error name from a E_* enum value
+ *
+ * @param error - E_* value
+ * @return string, error name
+ */
+const char *error_get_name(error_t error) __attribute__((pure));
+
 #ifdef __cplusplus
 }
 #endif
diff --git a/utils/hexdump.h b/utils/hexdump.h
index c1de480..f3d290c 100644
--- a/utils/hexdump.h
+++ b/utils/hexdump.h
@@ -1,6 +1,9 @@
 //
 // Created by MightyPork on 2017/12/04.
 //
+// Memory dumping utility from: https://stackoverflow.com/a/7776146/2180189
+// Prints bytes in the usual hexdump format (as HEX and ASCII)
+//
 
 #ifndef GEX_HEXDUMP_H
 #define GEX_HEXDUMP_H
diff --git a/utils/ini_parser.h b/utils/ini_parser.h
index 4265965..52b36ac 100644
--- a/utils/ini_parser.h
+++ b/utils/ini_parser.h
@@ -1,8 +1,14 @@
+//
+// INI file parser with a FSM generated by Ragel. This was originally written for ESPTerm
+// Used to extract sections, keys and values from user-provided settings file
+//
+
 #ifndef INIPARSE_STREAM_H
 #define INIPARSE_STREAM_H
 
 #include "platform.h"
 
+// toggleable logging func
 #ifdef DEBUG_INI
 #define ini_error(fmt, ...) dbg("! INI err: "#fmt, ##__VA_ARGS__)
 #else
diff --git a/utils/ini_writer.h b/utils/ini_writer.h
index 0ae4ca3..7212de9 100644
--- a/utils/ini_writer.h
+++ b/utils/ini_writer.h
@@ -1,12 +1,19 @@
 //
 // Created by MightyPork on 2017/12/01.
 //
+// Utility for generating a INI file with support for extracting individual sectors
+// and measuring total length without buffering. This is used to build the INI files
+// for the VFS and config.
+//
 
 #ifndef INIWRITER_H
 #define INIWRITER_H
 
 #include "platform.h"
 
+/**
+ * INI writer handle
+ */
 typedef struct iniwriter_ {
     char *ptr;
     uint32_t skip;
@@ -18,7 +25,7 @@ typedef struct iniwriter_ {
  *
  * This buffer is used internally by printf-like iw functions.
  * It can be used to prepare buffer for iw_buff or iw_string,
- * but must not be used for %s substitutions in iw_* functions.
+ * but must NOT be used for %s substitutions in iw_* functions.
  */
 extern char *iwbuffer;
 
diff --git a/utils/macro.h b/utils/macro.h
index 1c65320..130b7a8 100644
--- a/utils/macro.h
+++ b/utils/macro.h
@@ -1,3 +1,7 @@
+//
+// static assert and general purpose useful macros, borrowed in part from the DAPLink project
+//
+
 /**
  * @file    macro.h
  * @brief   useful things + Special asserts and macros
diff --git a/utils/malloc_safe.h b/utils/malloc_safe.h
index da3a6bd..5f9d372 100644
--- a/utils/malloc_safe.h
+++ b/utils/malloc_safe.h
@@ -1,3 +1,9 @@
+//
+// Safe malloc with error file:line logging, using the FreeRTOS-provided malloc facility
+// The custom malloc implementation is safer than the poorly documented hacks provided by
+// newlib, written primarily for the desktop rather than embedded.
+//
+
 #ifndef MALLOC_SAFE_H
 #define MALLOC_SAFE_H
 
diff --git a/utils/snprintf.h b/utils/snprintf.h
index 549c87c..a451969 100644
--- a/utils/snprintf.h
+++ b/utils/snprintf.h
@@ -1,6 +1,8 @@
 //
 // Created by MightyPork on 2017/11/09.
 //
+// Small sprintf/snprintf implementation, used instead of the newlib one.
+//
 
 #ifndef GEX_SNPRINTF_H
 #define GEX_SNPRINTF_H
@@ -15,13 +17,6 @@ size_t fixup_vasprintf(char **ptr, const char *format, va_list ap);
 size_t fixup_asprintf(char **ptr, const char *format, ...);
 size_t fixup_sprintf(char *ptr, const char *format, ...);
 
-// Trap for using newlib functions
-//#define vsnprintf fuck1
-//#define snprintf fuck2
-//#define vasprintf fuck3
-//#define asprintf fuck4
-//#define sprintf fuck5
-
 #define VSNPRINTF(...) fixup_vsnprintf(__VA_ARGS__)
 #define SNPRINTF(...) fixup_snprintf(__VA_ARGS__)
 #define VASPRINTF(...) fixup_vasprintf(__VA_ARGS__)
diff --git a/utils/stacksmon.c b/utils/stacksmon.c
index 1fce31c..0a765c7 100644
--- a/utils/stacksmon.c
+++ b/utils/stacksmon.c
@@ -15,7 +15,6 @@ struct stackhandle {
     uint32_t len;
 };
 
-#define STACK_NUM 3
 static uint32_t nextidx = 0;
 static struct stackhandle stacks[STACK_NUM];
 
diff --git a/utils/stacksmon.h b/utils/stacksmon.h
index 80dd3e5..cddc53b 100644
--- a/utils/stacksmon.h
+++ b/utils/stacksmon.h
@@ -1,6 +1,8 @@
 //
 // Created by MightyPork on 2017/12/04.
 //
+// Utility for monitoring usage levels of FreeRTOS stacks and printing it in a nice table
+//
 
 #ifndef GEX_STACKSMON_H
 #define GEX_STACKSMON_H
@@ -8,9 +10,29 @@
 #include "platform.h"
 
 #if USE_STACK_MONITOR
+
+/** Number of tracked stacks, max */
+#define STACK_NUM 3
+
+/**
+ * Check canaries and trap if they're dead
+ */
 void stackmon_check_canaries(void);
+
+/**
+ * Dump stacks usage table
+ */
 void stackmon_dump(void);
+
+/**
+ * Register a stack to be monitored
+ *
+ * @param description - stack name
+ * @param buffer - stack buffer
+ * @param len - stack size in bytes
+ */
 void stackmon_register(const char *description, void *buffer, uint32_t len);
+
 #else
 #define stackmon_check_canaries() do {} while(0)
 #define stackmon_dump() do {} while(0)
diff --git a/utils/str_utils.h b/utils/str_utils.h
index a4170e0..b25e6b6 100644
--- a/utils/str_utils.h
+++ b/utils/str_utils.h
@@ -1,3 +1,8 @@
+//
+// Simple string testing / manipulation functions, mainly used when
+// building/parsing the config INI files
+//
+
 #ifndef PLATFORSTR_UTILS_H
 #define PLATFORSTR_UTILS_H
 
@@ -125,17 +130,20 @@ const char *str_4(uint32_t n,
                      uint32_t nc, const char *c,
                      uint32_t nd, const char *d);
 
+/** Convert string to one of two numeric options */
 uint32_t str_parse_2(const char *tpl,
                      const char *a, uint32_t na,
                      const char *b, uint32_t nb,
                      bool *suc);
 
+/** Convert string to one of three numeric options */
 uint32_t str_parse_3(const char *tpl,
                      const char *a, uint32_t na,
                      const char *b, uint32_t nb,
                      const char *c, uint32_t nc,
                      bool *suc);
 
+/** Convert string to one of four numeric options */
 uint32_t str_parse_4(const char *tpl,
                      const char *a, uint32_t na,
                      const char *b, uint32_t nb,
@@ -143,7 +151,7 @@ uint32_t str_parse_4(const char *tpl,
                      const char *d, uint32_t nd,
                      bool *suc);
 
-/** Convert bool to Y or N */
+/** Convert bool to a Y or N constant string */
 #define str_yn(cond) ((cond) ? ("Y") : ("N"))
 
 #endif
diff --git a/version.h b/version.h
index 995e1e2..da30beb 100644
--- a/version.h
+++ b/version.h
@@ -1,6 +1,8 @@
 //
 // Created by MightyPork on 2017/12/08.
 //
+// GEX version string
+//
 
 #ifndef GEX_VERSION_H
 #define GEX_VERSION_H
diff --git a/vfs/file_stream.h b/vfs/file_stream.h
index 3d6e8d1..ab642f7 100644
--- a/vfs/file_stream.h
+++ b/vfs/file_stream.h
@@ -1,3 +1,8 @@
+//
+// File streams, this was used in DAPLink to capture and flash the firmware update image.
+// Here we detect only the settings INI files, which start by two hash symbols.
+//
+
 /**
  * @file    file_stream.h
  * @brief   Different file stream parsers that are supported
@@ -42,16 +47,19 @@ typedef enum {
     STREAM_TYPE_NONE
 } stream_type_t;
 
-// Stateless function to identify a filestream by its contents
+/** Stateless function to identify a filestream by its contents */
 stream_type_t stream_start_identify(const uint8_t *data, uint32_t size);
 
-// Stateless function to identify a filestream by its name
+/** Stateless function to identify a filestream by its name */
 stream_type_t stream_type_from_name(const vfs_filename_t filename);
 
+/** Open a stream (only one can be open at all times) */
 error_t stream_open(stream_type_t stream_type);
 
+/** Write some data to an open stream */
 error_t stream_write(const uint8_t *data, uint32_t size);
 
+/** Close the open stream */
 error_t stream_close(void);
 
 #ifdef __cplusplus
diff --git a/vfs/vfs_manager.c b/vfs/vfs_manager.c
index 152c915..1a3adc4 100644
--- a/vfs/vfs_manager.c
+++ b/vfs/vfs_manager.c
@@ -328,7 +328,7 @@ void vfs_if_usbd_msc_read_sect(uint32_t sector, uint8_t *buf, uint32_t num_of_se
     vfs_read(sector, buf, num_of_sectors);
 }
 
-void vfs_if_usbd_msc_write_sect(uint32_t sector, uint8_t *buf, uint32_t num_of_sectors)
+void vfs_if_usbd_msc_write_sect(uint32_t sector, const uint8_t *buf, uint32_t num_of_sectors)
 {
     sync_assert_usb_thread();
     vfs_printf("\033[32mWRITE @ %d, len %d\033[0m", (int)sector, (int)num_of_sectors);
diff --git a/vfs/vfs_manager.h b/vfs/vfs_manager.h
index b9c181e..7e35858 100644
--- a/vfs/vfs_manager.h
+++ b/vfs/vfs_manager.h
@@ -1,3 +1,10 @@
+//
+// The main VFS state machine, mostly based on DAPLink
+//
+// TODO many errors were originally written to a FAIL.TXT file for the user to see,
+//      those are now caught by assert_param(0) and crash the whole system. This is not ideal.
+//
+
 /**
  * @file    vfs_manager.h
  * @brief   Methods that build and manipulate a virtual file system
@@ -29,61 +36,114 @@
 extern "C" {
 #endif
 
+/**
+ * Flag that we're plugged into Windows.
+ * This is detected by characteristic writes of some system metadata store (which we discard)
+ */
 extern bool vfs_is_windows;
 
 /* Callable from anywhere */
 
-// Enable or disable the virtual filesystem
+/** Enable or disable the virtual filesystem */
 void vfs_mngr_fs_enable(bool enabled);
 
-// Remount the virtual filesystem
+/**
+ * Remount the virtual filesystem
+ *
+ * @param force_full - use media ready toggle instead of just notifying of modified data
+ *                     (this should be more reliable, but can also be more intrusive)
+ */
 void vfs_mngr_fs_remount(bool force_full);
 
 
 /* Callable only from the thread running the virtual fs */
 
-// Initialize the VFS manager
-// Must be called after USB has been initialized (usbd_init())
-// Notes: Must only be called from the thread runnning USB
+/**
+ * Initialize the VFS manager
+ * Must be called after USB has been initialized (usbd_init())
+ *
+ * @note Must only be called from the thread runnning USB
+ * @param enabled
+ */
 void vfs_mngr_init(bool enabled);
 
-// Run the vfs manager state machine
-// Notes: Must only be called from the thread runnning USB
+
+/**
+ * Run the vfs manager state machine
+ *
+ * @note Must only be called from the thread runnning USB
+ * @param elapsed_ms
+ */
 void vfs_mngr_periodic(uint32_t elapsed_ms);
 
-// Return the status of the last transfer or E_SUCCESS
-// if none have been performed yet
+/**
+ * Return the status of the last transfer or E_SUCCESS
+ * if none have been performed yet
+ *
+ * @return success
+ */
 error_t vfs_mngr_get_transfer_status(void);
 
 
 /* Use functions */
 
-// Build the filesystem by calling vfs_init and then adding files with vfs_create_file
+/**
+ * Build the filesystem by calling vfs_init and then adding files with vfs_create_file
+ */
 void vfs_user_build_filesystem(void);
 
-// Called when a file on the filesystem changes
-void vfs_user_file_change_handler(const vfs_filename_t filename, vfs_file_change_t change, vfs_file_t file, vfs_file_t new_file_data);
+/**
+ * Called when a file on the filesystem changes
+ *
+ * @param filename - name of the changed file
+ * @param change - type of change
+ * @param file - data pointer (?)
+ * @param new_file_data - new data pointer (?)
+ */
+void vfs_user_file_change_handler(const vfs_filename_t filename,
+                                  vfs_file_change_t change,
+                                  vfs_file_t file, vfs_file_t new_file_data);
 
-// Called when VFS is disconnecting
+/**
+ * Called when VFS is disconnecting
+ */
 void vfs_user_disconnecting(void);
 
-
-
 // --- interface ---
+
+/**
+ * Initialize, call form the MSC init callback
+ */
 void vfs_if_usbd_msc_init(void);
+
+/**
+ * MSC wants to read a sector
+ *
+ * @param sector - first sector number
+ * @param buf - destination
+ * @param num_of_sectors - length
+ */
 void vfs_if_usbd_msc_read_sect(uint32_t sector, uint8_t *buf, uint32_t num_of_sectors);
-void vfs_if_usbd_msc_write_sect(uint32_t sector, uint8_t *buf, uint32_t num_of_sectors);
+
+/**
+ * MSC wants to write a sector
+ *
+ * @param sector - first sector number
+ * @param buf - data
+ * @param num_of_sectors - length
+ */
+void vfs_if_usbd_msc_write_sect(uint32_t sector, const uint8_t *buf, uint32_t num_of_sectors);
 
 typedef struct {
     uint32_t MemorySize;
     uint16_t BlockSize;
-    uint32_t BlockGroup; // LUN?
+    uint32_t BlockGroup; // LUN
     uint32_t BlockCount;
-//    uint8_t *BlockBuf; // apparently unused :thaenkin:
     bool MediaReady;
     bool MediaChanged;
 } vfs_info_t;
 
+/** VFS info struct - some are used by SCSI/MSC */
 extern volatile vfs_info_t vfs_info;
 
 #ifdef __cplusplus
diff --git a/vfs/vfs_user.c b/vfs/vfs_user.c
index 653225c..cad2cee 100644
--- a/vfs/vfs_user.c
+++ b/vfs/vfs_user.c
@@ -1,3 +1,7 @@
+//
+// Here are defined the files and handlers
+//
+
 /**
  * @file    vfs_user.c
  * @brief   Implementation of vfs_user.h
@@ -27,6 +31,7 @@
 
 const vfs_filename_t daplink_drive_name = VFS_DRIVE_NAME;
 
+
 static uint32_t read_iw_sector(uint32_t sector_offset, uint8_t *data, uint32_t num_sectors, void (*handler)(IniWriter *))
 {
     const uint32_t avail = num_sectors*VFS_SECTOR_SIZE;
@@ -38,6 +43,7 @@ static uint32_t read_iw_sector(uint32_t sector_offset, uint8_t *data, uint32_t n
     return avail - iw.count;
 }
 
+
 // File callback to be used with vfs_add_file to return file contents
 static uint32_t read_file_units_ini(uint32_t sector_offset, uint8_t *data, uint32_t num_sectors)
 {
@@ -45,18 +51,21 @@ static uint32_t read_file_units_ini(uint32_t sector_offset, uint8_t *data, uint3
     return read_iw_sector(sector_offset, data, num_sectors, settings_build_units_ini);
 }
 
+
 static uint32_t read_file_system_ini(uint32_t sector_offset, uint8_t *data, uint32_t num_sectors)
 {
     vfs_printf("Read SYSTEM.INI");
     return read_iw_sector(sector_offset, data, num_sectors, settings_build_system_ini);
 }
 
+
 static uint32_t read_file_pinout_txt(uint32_t sector_offset, uint8_t *data, uint32_t num_sectors)
 {
     vfs_printf("Read PINOUT.TXT");
     return read_iw_sector(sector_offset, data, num_sectors, settings_build_pinout_txt);
 }
 
+
 void vfs_user_build_filesystem(void)
 {
     dbg("Rebuilding VFS...");
@@ -69,6 +78,7 @@ void vfs_user_build_filesystem(void)
     vfs_create_file("PINOUT  TXT", read_file_pinout_txt, NULL, iw_measure_total(settings_build_pinout_txt));
 }
 
+
 // Callback to handle changes to the root directory.  Should be used with vfs_set_file_change_callback
 void vfs_user_file_change_handler(const vfs_filename_t filename,
                                   vfs_file_change_t change,
@@ -98,6 +108,7 @@ void vfs_user_file_change_handler(const vfs_filename_t filename,
     }
 }
 
+
 void vfs_user_disconnecting(void)
 {
     // maybe reset...
diff --git a/vfs/virtual_fs.h b/vfs/virtual_fs.h
index 5b75b41..e0066e7 100644
--- a/vfs/virtual_fs.h
+++ b/vfs/virtual_fs.h
@@ -1,3 +1,8 @@
+//
+// The guts of the virtual FAT16 are implemented here.
+// This is taken from DAPLink and some memory-wasting bits are commented out or removed.
+//
+
 /**
  * @file    virtual_fs.h
  * @brief   FAT 12/16 filesystem handling
@@ -28,6 +33,7 @@
 extern "C" {
 #endif
 
+// Toggleable debug funcs
 #if DEBUG_VFS
 #define vfs_printf(...)  do { dbg(__VA_ARGS__); } while(0)
 #define vfs_printf_nonl(...)  do { PRINTF(__VA_ARGS__); } while(0)
@@ -48,6 +54,7 @@ extern "C" {
 #define VFS_MAX_FILES           16
 #define VFS_DISK_SIZE MB(32)
 
+/** Filename typedef */
 typedef char vfs_filename_t[11];
 
 typedef enum {
@@ -69,51 +76,116 @@ typedef enum {
                                   notification will also occur*/
 } vfs_file_change_t;
 
+/** File typedef */
 typedef void *vfs_file_t;
+
+/** Sector struct typedef */
 typedef uint32_t vfs_sector_t;
 
-// Callback for when data is written to a file on the virtual filesystem
+/**
+ * Callback for when data is written to a file on the virtual filesystem
+ */
 typedef void (*vfs_write_cb_t)(uint32_t sector_offset, const uint8_t *data, uint32_t num_sectors);
-// Callback for when data is ready from the virtual filesystem
+
+/**
+ * Callback for when data is ready from the virtual filesystem
+ */
 typedef uint32_t (*vfs_read_cb_t)(uint32_t sector_offset, uint8_t *data, uint32_t num_sectors);
-// Callback for when a file's attributes are changed on the virtual filesystem.  Note that the 'file' parameter
-// can be saved and compared to other files to see if they are referencing the same object.  The
-// same cannot be done with new_file_data since it points to a temporary buffer.
+
+/**
+ * Callback for when a file's attributes are changed on the virtual filesystem.
+ * Note that the 'file' parameter can be saved and compared to other files to see if
+ * they are referencing the same object. The same cannot be done with new_file_data
+ * since it points to a temporary buffer.
+ */
 typedef void (*vfs_file_change_cb_t)(const vfs_filename_t filename, vfs_file_change_t change,
                                      vfs_file_t file, vfs_file_t new_file_data);
 
-// Initialize the filesystem with the given size and name
+/**
+ * Initialize the filesystem with the given size and name
+ *
+ * @param drive_name
+ * @param disk_size
+ */
 void vfs_init(const vfs_filename_t drive_name, uint32_t disk_size);
 
-// Get the total size of the virtual filesystem
+/**
+ * Get the total size of the virtual filesystem
+ */
 uint32_t vfs_get_total_size(void);
 
-// Add a file to the virtual FS and return a handle to this file.
-// This must be called before vfs_read or vfs_write are called.
-// Adding a new file after vfs_read or vfs_write have been called results in undefined behavior.
-vfs_file_t vfs_create_file(const vfs_filename_t filename, vfs_read_cb_t read_cb, vfs_write_cb_t write_cb, uint32_t len);
+/**
+ * Add a file to the virtual FS and return a handle to this file.
+ * This must be called before vfs_read or vfs_write are called.
+ * Adding a new file after vfs_read or vfs_write have been called results in undefined behavior.
+ *
+ * @param filename
+ * @param read_cb
+ * @param write_cb
+ * @param len
+ * @return
+ */
+vfs_file_t vfs_create_file(const vfs_filename_t filename,
+                           vfs_read_cb_t read_cb, vfs_write_cb_t write_cb,
+                           uint32_t len);
 
-// Set the attributes of a file
+/**
+ * Set the attributes of a file
+ *
+ * @param file
+ * @param attr
+ */
 void vfs_file_set_attr(vfs_file_t file, vfs_file_attr_bit_t attr);
 
-// Get the starting sector of this file.
-// NOTE - If the file size is 0 there is no starting
-// sector so VFS_INVALID_SECTOR will be returned.
+/**
+ * Get the starting sector of this file.
+ * NOTE - If the file size is 0 there is no starting
+ * sector so VFS_INVALID_SECTOR will be returned.
+ *
+ * @param file
+ * @return
+ */
 vfs_sector_t vfs_file_get_start_sector(vfs_file_t file);
 
-// Get the size of the file.
+/**
+ * Get the size of the file.
+ *
+ * @param file
+ * @return
+ */
 uint32_t vfs_file_get_size(vfs_file_t file);
 
-// Get the attributes of a file
+/**
+ * Get the attributes of a file
+ *
+ * @param file
+ * @return
+ */
 vfs_file_attr_bit_t vfs_file_get_attr(vfs_file_t file);
 
-// Set the callback when a file is created, deleted or has atributes changed.
+/**
+ * Set the callback when a file is created, deleted or has atributes changed.
+ *
+ * @param cb
+ */
 void vfs_set_file_change_callback(vfs_file_change_cb_t cb);
 
-// Read one or more sectors from the virtual filesystem
+/**
+ * Read one or more sectors from the virtual filesystem
+ *
+ * @param sector
+ * @param buf
+ * @param num_of_sectors
+ */
 void vfs_read(uint32_t sector, uint8_t *buf, uint32_t num_of_sectors);
 
-// Write one or more sectors to the virtual filesystem
+/**
+ * Write one or more sectors to the virtual filesystem
+ *
+ * @param sector
+ * @param buf
+ * @param num_of_sectors
+ */
 void vfs_write(uint32_t sector, const uint8_t *buf, uint32_t num_of_sectors);
 
 bool vfs_find_file(uint32_t start_sector, vfs_filename_t *destFilename, vfs_file_t **destFile);