diff --git a/Makefile b/Makefile
index fad9eb6d..9c597a3b 100644
--- a/Makefile
+++ b/Makefile
@@ -5,7 +5,7 @@
 
 # Compiler options here.
 ifeq ($(USE_OPT),)
-  USE_OPT = -O2 -ggdb -fomit-frame-pointer -falign-functions=16 --specs=nano.specs
+  USE_OPT = -O2 -ggdb -fomit-frame-pointer -falign-functions=16 --specs=nano.specs -fstack-usage
 endif
 
 # C specific options here (added to USE_OPT).
diff --git a/chconf.h b/chconf.h
index 5599a4b4..05112aa4 100644
--- a/chconf.h
+++ b/chconf.h
@@ -526,6 +526,19 @@
 
 #define CHPRINTF_USE_FLOAT          TRUE
 
+/**
+ * ChibiOS/os/various/shell/shell_cmd.c
+ */
+#define SHELL_CMD_EXIT_ENABLED TRUE
+#define SHELL_CMD_INFO_ENABLED TRUE
+#define SHELL_CMD_ECHO_ENABLED FALSE
+#define SHELL_CMD_SYSTIME_ENABLED FALSE
+#define SHELL_CMD_MEM_ENABLED FALSE
+#define SHELL_CMD_THREADS_ENABLED TRUE
+#define SHELL_CMD_TEST_ENABLED FALSE
+
+
+
 #endif  /* _CHCONF_H_ */
 
 /** @} */
diff --git a/main.c b/main.c
index 3ca4e5c7..7947fc67 100644
--- a/main.c
+++ b/main.c
@@ -53,7 +53,7 @@ int8_t cal_auto_interpolate = TRUE;
 int8_t redraw_requested = FALSE;
 int8_t stop_the_world = FALSE;
 
-static THD_WORKING_AREA(waThread1, 768);
+static THD_WORKING_AREA(waThread1, 640);
 static THD_FUNCTION(Thread1, arg)
 {
     (void)arg;
@@ -1289,7 +1289,7 @@ const struct {
   { "X",      4, 100 }
 };
 
-const char *trc_channel_name[] = {
+const char * const trc_channel_name[] = {
   "CH0", "CH1"
 };
 
@@ -1737,8 +1737,7 @@ static void cmd_version(BaseSequentialStream *chp, int argc, char *argv[])
   chprintf(chp, "%s\r\n", NANOVNA_VERSION);
 }
 
-#define SHELL_WA_SIZE THD_WORKING_AREA_SIZE(256)
-static THD_WORKING_AREA(waThread2, SHELL_WA_SIZE);
+static THD_WORKING_AREA(waThread2, /* cmd_* max stack size + alpha */410);
 
 static const ShellCommand commands[] =
 {
diff --git a/plot.c b/plot.c
index 8327504f..4055870b 100644
--- a/plot.c
+++ b/plot.c
@@ -7,7 +7,7 @@
 
 #define SWAP(x,y) do { int z=x; x = y; y = z; } while(0)
 
-void cell_draw_marker_info(int m, int n, int w, int h);
+static void cell_draw_marker_info(int m, int n, int w, int h);
 void draw_frequencies(void);
 void frequency_string(char *buf, size_t len, int32_t freq);
 void markmap_all_markers(void);
@@ -534,7 +534,7 @@ trace_into_index(int x, int t, int i, float coeff[2])
   return INDEX(x +CELLOFFSETX, y, i);
 }
 
-int
+static int
 string_value_with_prefix(char *buf, int len, float val, char unit)
 {
   char prefix;
@@ -591,7 +591,7 @@ string_value_with_prefix(char *buf, int len, float val, char unit)
 
 #define PI2 6.283184
 
-void
+static void
 gamma2imp(char *buf, int len, const float coeff[2], uint32_t frequency)
 {
   // z = (gamma+1)/(gamma-1) * z0
@@ -613,7 +613,7 @@ gamma2imp(char *buf, int len, const float coeff[2], uint32_t frequency)
   }
 }
 
-void
+static void
 gamma2resistance(char *buf, int len, const float coeff[2], uint32_t frequency)
 {
   float z0 = 50;
@@ -622,7 +622,7 @@ gamma2resistance(char *buf, int len, const float coeff[2], uint32_t frequency)
   string_value_with_prefix(buf, len, zr, S_OHM[0]);
 }
 
-void
+static void
 gamma2reactance(char *buf, int len, const float coeff[2], uint32_t frequency)
 {
   float z0 = 50;
@@ -631,7 +631,7 @@ gamma2reactance(char *buf, int len, const float coeff[2], uint32_t frequency)
   string_value_with_prefix(buf, len, zi, S_OHM[0]);
 }
 
-void
+static void
 trace_get_value_string(int t, char *buf, int len, float coeff[2], uint32_t frequency)
 {
   float v;
@@ -721,7 +721,7 @@ markmap_upperarea(void)
   markmap[current_mappage][0] |= 0xffff;
 }
 
-static void
+static inline void
 swap_markmap(void)
 {
   current_mappage = 1 - current_mappage;
@@ -733,7 +733,7 @@ clear_markmap(void)
   memset(markmap[current_mappage], 0, sizeof markmap[current_mappage]);
 }
 
-void
+void inline
 force_set_markmap(void)
 {
   memset(markmap[current_mappage], 0xff, sizeof markmap[current_mappage]);
@@ -1107,7 +1107,7 @@ markmap_all_markers(void)
 }
 
 
-void
+static void
 draw_cell(int m, int n)
 {
   int x0 = m * CELLWIDTH;
@@ -1330,7 +1330,7 @@ cell_drawstring_invert_5x7(int w, int h, char *str, int x, int y, uint16_t fg, i
   }
 }
 
-void
+static void
 cell_draw_marker_info(int m, int n, int w, int h)
 {
   char buf[24];
diff --git a/ui.c b/ui.c
index f68a4444..9e7f090e 100644
--- a/ui.c
+++ b/ui.c
@@ -112,7 +112,7 @@ void draw_menu(void);
 void leave_ui_mode(void);
 void erase_menu_buttons(void);
 void ui_process_keypad(void);
-void ui_process_numeric(void);
+static void ui_process_numeric(void);
 
 static void menu_push_submenu(const menuitem_t *submenu);
 
@@ -1042,7 +1042,7 @@ const keypads_t keypads_time[] = {
   { 0, 0, -1 }
 };
 
-const keypads_t *keypads_mode_tbl[] = {
+const keypads_t * const keypads_mode_tbl[] = {
   keypads_freq, // start
   keypads_freq, // stop
   keypads_freq, // center
@@ -1053,7 +1053,7 @@ const keypads_t *keypads_mode_tbl[] = {
   keypads_time // electrical delay
 };
 
-const char *keypad_mode_label[] = {
+const char * const keypad_mode_label[] = {
   "START", "STOP", "CENTER", "SPAN", "CW FREQ", "SCALE", "REFPOS", "EDELAY"
 };
 
@@ -1409,7 +1409,7 @@ ui_mode_normal(void)
   ui_mode = UI_NORMAL;
 }
 
-void
+static void
 ui_process_normal(void)
 {
   int status = btn_check();
@@ -1438,7 +1438,7 @@ ui_process_normal(void)
   }
 }
 
-void
+static void
 ui_process_menu(void)
 {
   int status = btn_check();
@@ -1463,7 +1463,7 @@ ui_process_menu(void)
   }
 }
 
-int
+static int
 keypad_click(int key) 
 {
   int c = keypads[key].c;
@@ -1527,7 +1527,7 @@ keypad_click(int key)
   return KP_CONTINUE;
 }
 
-int
+static int
 keypad_apply_touch(void)
 {
   int touch_x, touch_y;
@@ -1556,7 +1556,7 @@ keypad_apply_touch(void)
   return -1;
 }
 
-void
+static void
 numeric_apply_touch(void)
 {
   int touch_x, touch_y;
@@ -1597,7 +1597,7 @@ numeric_apply_touch(void)
   return;
 }
 
-void
+static void
 ui_process_numeric(void)
 {
   int status = btn_check();
@@ -1720,7 +1720,7 @@ ui_process_keypad(void)
   touch_start_watchdog();
 }
 
-void
+static void
 ui_process_lever(void)
 {
   switch (ui_mode) {
@@ -1740,7 +1740,8 @@ ui_process_lever(void)
 }
 
 
-void drag_marker(int t, int m)
+static void
+drag_marker(int t, int m)
 {
   int status;
   /* wait touch release */
@@ -1767,7 +1768,7 @@ sq_distance(int x0, int y0)
   return x0*x0 + y0*y0;
 }
 
-int
+static int
 touch_pickup_marker(void)
 {
   int touch_x, touch_y;
@@ -1807,7 +1808,7 @@ touch_pickup_marker(void)
 }
 
 
-
+static
 void ui_process_touch(void)
 {
   awd_count++;