diff --git a/Makefile b/Makefile
index 726e18b..a3adad2 100644
--- a/Makefile
+++ b/Makefile
@@ -60,13 +60,13 @@ endif
 # Stack size to be allocated to the Cortex-M process stack. This stack is
 # the stack used by the main() thread.
 ifeq ($(USE_PROCESS_STACKSIZE),)
-  USE_PROCESS_STACKSIZE = 0x200
+  USE_PROCESS_STACKSIZE = 0x280
 endif
 
 # Stack size to the allocated to the Cortex-M main/exceptions stack. This
 # stack is used for processing interrupts and exceptions.
 ifeq ($(USE_EXCEPTIONS_STACKSIZE),)
-  USE_EXCEPTIONS_STACKSIZE = 0x300
+  USE_EXCEPTIONS_STACKSIZE = 0x280
 endif
 
 #
diff --git a/main.c b/main.c
index 7bf1f92..ba496a8 100644
--- a/main.c
+++ b/main.c
@@ -446,6 +446,7 @@ void scan_lcd(void)
   draw_cell_all();
 }
 
+#if 0
 static void cmd_scan_lcd(BaseSequentialStream *chp, int argc, char *argv[])
 {
   (void)chp;
@@ -454,7 +455,7 @@ static void cmd_scan_lcd(BaseSequentialStream *chp, int argc, char *argv[])
   pause_sweep();
   scan_lcd();
 }
-
+#endif
 
 void
 set_frequencies(void)
@@ -841,6 +842,30 @@ const char *trc_channel_name[] = {
   "S11", "S21"
 };
 
+void set_trace_type(int t, int type)
+{
+  int polar = type == TRC_SMITH || type == TRC_ADMIT || type == TRC_POLAR;
+  int enabled = type != TRC_OFF;
+  int force = FALSE;
+
+  if (trace[t].polar != polar) {
+    trace[t].polar = polar;
+    force = TRUE;
+  }
+  if (trace[t].enabled != enabled) {
+    trace[t].enabled = enabled;
+    force = TRUE;
+  }
+  if (trace[t].type != type) {
+    trace[t].type = type;
+    if (polar)
+      force = TRUE;
+  }    
+  if (force)
+    //force_draw_cells();
+    force_set_markmap();
+}
+
 static void cmd_trace(BaseSequentialStream *chp, int argc, char *argv[])
 {
   int t;
@@ -865,35 +890,21 @@ static void cmd_trace(BaseSequentialStream *chp, int argc, char *argv[])
   }
   if (argc > 1) {
     if (strcmp(argv[1], "logmag") == 0) {
-      trace[t].type = TRC_LOGMAG;
-      trace[t].polar = FALSE;
-      trace[t].enabled = TRUE;
+      set_trace_type(t, TRC_LOGMAG);
     } else if (strcmp(argv[1], "phase") == 0) {
-      trace[t].type = TRC_PHASE;
-      trace[t].polar = FALSE;
-      trace[t].enabled = TRUE;
+      set_trace_type(t, TRC_PHASE);
     } else if (strcmp(argv[1], "polar") == 0) {
-      trace[t].type = TRC_POLAR;
-      trace[t].polar = TRUE;
-      trace[t].enabled = TRUE;
+      set_trace_type(t, TRC_POLAR);
     } else if (strcmp(argv[1], "smith") == 0) {
-      trace[t].type = TRC_SMITH;
-      trace[t].polar = TRUE;
-      trace[t].enabled = TRUE;
+      set_trace_type(t, TRC_SMITH);
     } else if (strcmp(argv[1], "admit") == 0) {
-      trace[t].type = TRC_ADMIT;
-      trace[t].polar = TRUE;
-      trace[t].enabled = TRUE;
+      set_trace_type(t, TRC_ADMIT);
     } else if (strcmp(argv[1], "linear") == 0) {
-      trace[t].type = TRC_LINEAR;
-      trace[t].polar = FALSE;
-      trace[t].enabled = TRUE;
+      set_trace_type(t, TRC_LINEAR);
     } else if (strcmp(argv[1], "swr") == 0) {
-      trace[t].type = TRC_SWR;
-      trace[t].polar = FALSE;
-      trace[t].enabled = TRUE;
+      set_trace_type(t, TRC_SWR);
     } else if (strcmp(argv[1], "off") == 0) {
-      trace[t].enabled = FALSE;
+      set_trace_type(t, TRC_OFF);
     } else if (strcmp(argv[1], "scale") == 0 && argc >= 3) {
       trace[t].scale = atoi(argv[2]);
       goto exit;
@@ -1081,7 +1092,7 @@ static const ShellCommand commands[] =
     { "scan", cmd_scan },
     { "sweep", cmd_sweep },
     { "test", cmd_test },
-    { "plot", cmd_scan_lcd },
+    //{ "plot", cmd_scan_lcd },
     { "pause", cmd_pause },
     { "resume", cmd_resume },
     { "cal", cmd_cal },
diff --git a/nanovna.h b/nanovna.h
index 378e1ab..c9dbd99 100644
--- a/nanovna.h
+++ b/nanovna.h
@@ -75,11 +75,13 @@ void ili9341_drawstring_5x7(char *str, int x, int y, uint16_t fg, uint16_t bg);
 #define WIDTH 291
 #define HEIGHT 233
 
-#define GRIDY 29
-
 extern int area_width;
 extern int area_height;
 
+#define GRIDY 29
+
+// font
+
 extern const uint16_t x5x7_bits [];
 extern const uint32_t numfont20x24[][24];
 
@@ -88,10 +90,12 @@ extern const uint32_t numfont20x24[][24];
 #define S_OHM   "\036"
 #define S_DEGREE "\037"
 
+// trace 
+
 #define TRACES_MAX 4
 
 enum {
-  TRC_LOGMAG, TRC_PHASE, TRC_SMITH, TRC_ADMIT, TRC_POLAR, TRC_LINEAR, TRC_SWR
+  TRC_LOGMAG, TRC_PHASE, TRC_SMITH, TRC_ADMIT, TRC_POLAR, TRC_LINEAR, TRC_SWR, TRC_OFF
 };
 
 extern const char *trc_type_name[];
@@ -116,7 +120,11 @@ typedef struct {
   uint8_t polar;
 } trace_t;
 
-extern trace_t trace[TRACES_MAX];
+//extern trace_t trace[TRACES_MAX];
+
+void set_trace_type(int t, int type);
+
+// marker
 
 typedef struct {
   int enabled;
@@ -135,6 +143,7 @@ void redraw_marker(int marker, int update_info);
 void trace_get_info(int t, char *buf, int len);
 void plot_into_index(float measured[2][101][2]);
 void draw_cell_all(void);
+void force_set_markmap(void);
 
 void draw_cal_status(void);
 
diff --git a/plot.c b/plot.c
index c0d5c38..f820051 100644
--- a/plot.c
+++ b/plot.c
@@ -9,7 +9,6 @@
 
 void cell_draw_marker_info(int m, int n, int w, int h);
 void draw_frequencies(void);
-static inline void force_set_markmap(void);
 void frequency_string(char *buf, size_t len, uint32_t freq);
 void markmap_all_markers(void);
 
@@ -176,10 +175,15 @@ smith_grid(int x, int y)
     return 0;
   if (d == 0)
     return c;
+  
+  // horizontal axis
+  if (y == 0)
+    return c;
 
   // shift circle center to right origin
   x -= P_RADIUS;
 
+
   // Constant Reactance Circle: 2j : R/2 = 58
   if (circle_inout(x, y+58, 58) == 0)
     return c;
@@ -297,6 +301,56 @@ smith_grid2(int x, int y, float scale)
   return 0;
 }
 
+
+const int cirs[][4] = {
+  { 0, 58/2, 58/2, 0 },    // Constant Reactance Circle: 2j : R/2 = 58
+  { 29/2, 0, 29/2, 1 },    // Constant Resistance Circle: 3 : R/4 = 29
+  { 0, 116/2, 116/2, 0 },  // Constant Reactance Circle: 1j : R = 116
+  { 58/2, 0, 58/2, 1 },    // Constant Resistance Circle: 1 : R/2 = 58
+  { 0, 232/2, 232/2, 0 },  // Constant Reactance Circle: 1/2j : R*2 = 232
+  { 87/2, 0, 87/2, 1 },    // Constant Resistance Circle: 1/3 : R*3/4 = 87
+  { 0, 464/2, 464/2, 0 },  // Constant Reactance Circle: 1/4j : R*4 = 464
+  { 116/2, 0, 116/2, 1 },  // Constant Resistance Circle: 0 : R
+  { 174/2, 0, 174/2, 1 },  // Constant Resistance Circle: -1/3 : R*3/2 = 174
+  { 0, 0, 0, 0 } // sentinel
+};  
+
+int
+smith_grid3(int x, int y)
+{
+  int c = grid_color;
+  int d;
+
+  // offset to center
+  x -= P_CENTER_X;
+  y -= P_CENTER_Y;
+  
+  // outer circle
+  d = circle_inout(x, y, P_RADIUS);
+  if (d < 0)
+    return 0;
+  if (d == 0)
+    return c;
+
+  // shift circle center to right origin
+  x -= P_RADIUS /2;
+
+  int i;
+  for (i = 0; cirs[i][2]; i++) {
+    d = circle_inout(x+cirs[i][0], y+cirs[i][1], cirs[i][2]);
+    if (d == 0)
+      return c;
+    if (d > 0 && cirs[i][3])
+      return 0;
+    d = circle_inout(x-cirs[i][0], y-cirs[i][1], cirs[i][2]);
+    if (d == 0)
+      return c;
+    if (d > 0 && cirs[i][3])
+      return 0;
+  }
+  return 0;
+}
+
 #if 0
 int
 rectangular_grid(int x, int y)
@@ -657,7 +711,7 @@ clear_markmap(void)
   memset(markmap[current_mappage], 0, sizeof markmap[current_mappage]);
 }
 
-static inline void
+void
 force_set_markmap(void)
 {
   memset(markmap[current_mappage], 0xff, sizeof markmap[current_mappage]);
@@ -937,6 +991,11 @@ markmap_all_markers(void)
 int area_width = WIDTH;
 int area_height = HEIGHT;
 
+#define GRID_RECTANGULAR (1<<0)
+#define GRID_SMITH       (1<<1)
+#define GRID_ADMIT       (1<<2)
+#define GRID_POLAR       (1<<3)
+
 void
 draw_cell(int m, int n)
 {
@@ -956,25 +1015,51 @@ draw_cell(int m, int n)
   if (w <= 0 || h <= 0)
     return;
 
+  uint16_t grid_mode = 0;
+  for (t = 0; t < TRACES_MAX; t++) {
+    if (!trace[t].enabled)
+      continue;
+    if (!trace[t].polar)
+      grid_mode |= GRID_RECTANGULAR;
+    else {
+      if (trace[t].type == TRC_SMITH)
+        grid_mode |= GRID_SMITH;
+      else if (trace[t].type == TRC_ADMIT)
+        grid_mode |= GRID_ADMIT;
+      else
+        grid_mode |= GRID_POLAR;
+    }
+  }
+
   PULSE;
   /* draw grid */
-  for (x = 0; x < w; x++) {
-    uint16_t c = rectangular_grid_x(x+x0);
-    for (y = 0; y < h; y++)
-      spi_buffer[y * w + x] = c;
-  }
-  for (y = 0; y < h; y++) {
-    uint16_t c = rectangular_grid_y(y+y0);
-    for (x = 0; x < w; x++)
-      spi_buffer[y * w + x] |= c;
-  }
-  for (y = 0; y < h; y++) {
+  if (grid_mode & GRID_RECTANGULAR) {
     for (x = 0; x < w; x++) {
-      //uint16_t c = rectangular_grid(x+x0, y+y0);
-      uint16_t c = smith_grid(x+x0, y+y0);
-      //uint16_t c = smith_grid2(x+x0, y+y0, 0.5);
-      //uint16_t c = polar_grid(x+x0, y+y0);
-      spi_buffer[y * w + x] |= c;
+      uint16_t c = rectangular_grid_x(x+x0);
+      for (y = 0; y < h; y++)
+        spi_buffer[y * w + x] = c;
+    }
+    for (y = 0; y < h; y++) {
+      uint16_t c = rectangular_grid_y(y+y0);
+      for (x = 0; x < w; x++)
+        spi_buffer[y * w + x] |= c;
+    }
+  } else {
+    memset(spi_buffer, 0, sizeof spi_buffer);
+  }
+  if (grid_mode & (GRID_SMITH|GRID_ADMIT|GRID_POLAR)) {
+    for (y = 0; y < h; y++) {
+      for (x = 0; x < w; x++) {
+        uint16_t c = 0;
+        if (grid_mode & GRID_SMITH)
+          c = smith_grid(x+x0, y+y0);
+        else if (grid_mode & GRID_ADMIT)
+          c = smith_grid3(x+x0, y+y0);
+        //c = smith_grid2(x+x0, y+y0, 0.5);
+        else if (grid_mode & GRID_POLAR)
+          c = polar_grid(x+x0, y+y0);
+        spi_buffer[y * w + x] |= c;
+      }
     }
   }
   PULSE;
diff --git a/ui.c b/ui.c
index dec8842..ca62be1 100644
--- a/ui.c
+++ b/ui.c
@@ -37,9 +37,9 @@ struct {
 #define EVT_DOWN				0x20
 #define EVT_REPEAT				0x40
 
-#define BUTTON_DOWN_LONG_TICKS		10000
-#define BUTTON_DOUBLE_TICKS			5000
-#define BUTTON_DEBOUNCE_TICKS		10
+#define BUTTON_DOWN_LONG_TICKS		1000
+#define BUTTON_DOUBLE_TICKS			500
+#define BUTTON_DEBOUNCE_TICKS		2
 
 /* lever switch assignment */
 #define BIT_UP1 	3
@@ -231,16 +231,19 @@ menu_trace_cb(int item)
   if (item < 0 || item >= 4)
     return;
   uistat.current_trace = item;
+  menu_move_back();
 }
 
 static void
 menu_format_cb(int item)
 {
-  trace[uistat.current_trace].type = item;
+  set_trace_type(uistat.current_trace, item);
+  ui_status = FALSE;
+  ui_hide();
 }
 
 static void 
-elect_active_marker(void)
+choose_active_marker(void)
 {
   int i;
   for (i = 0; i < 4; i++)
@@ -259,7 +262,7 @@ menu_marker_cb(int item)
 
   if (active_marker == item) {
     markers[active_marker].enabled = FALSE;
-    elect_active_marker();
+    choose_active_marker();
   } else {
     active_marker = item;
     markers[active_marker].enabled = TRUE;