diff --git a/openrtx/include/interfaces/datatypes.h b/openrtx/include/interfaces/datatypes.h
new file mode 100644
index 00000000..01a43fc8
--- /dev/null
+++ b/openrtx/include/interfaces/datatypes.h
@@ -0,0 +1,42 @@
+/***************************************************************************
+ *   Copyright (C) 2020 by Federico Amedeo Izzo IU2NUO,                    *
+ *                         Niccolò Izzo IU2KIN,                            *
+ *                         Silvano Seva IU2KWO                             *
+ *                                                                         *
+ *   This program is free software; you can redistribute it and/or modify  *
+ *   it under the terms of the GNU General Public License as published by  *
+ *   the Free Software Foundation; either version 3 of the License, or     *
+ *   (at your option) any later version.                                   *
+ *                                                                         *
+ *   This program is distributed in the hope that it will be useful,       *
+ *   but WITHOUT ANY WARRANTY; without even the implied warranty of        *
+ *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         *
+ *   GNU General Public License for more details.                          *
+ *                                                                         *
+ *   You should have received a copy of the GNU General Public License     *
+ *   along with this program; if not, see <http://www.gnu.org/licenses/>   *
+ ***************************************************************************/
+
+#ifndef DATATYPES_H
+#define DATATYPES_H
+
+/**                                                                             
+ * \brief CTCSS and DCS type definition.                                        
+ *                                                                              
+ * Continuous Tone Controlled Squelch System (CTCSS)                            
+ * sub-audible tone frequency are expressed in \em tenth of Hz.                 
+ * For example, the subaudible tone of 88.5 Hz is represented within            
+ * Hamlib by 885.                                                               
+ *                                                                              
+ * Digitally-Coded Squelch codes are simple direct integers.                    
+ */                                                                             
+typedef unsigned int tone_t;
+ 
+/**                                                                             
+ * \brief Frequency type,                                                       
+ *                                                                              
+ * Frequency type unit in Hz, able to hold SHF frequencies.                     
+ */ 
+typedef float freq_t;
+
+#endif /* DATATYPES_H */
diff --git a/openrtx/include/interfaces/state.h b/openrtx/include/interfaces/state.h
index ec023b32..8ab6cd29 100644
--- a/openrtx/include/interfaces/state.h
+++ b/openrtx/include/interfaces/state.h
@@ -20,6 +20,8 @@
 #ifndef STATE_H
 #define STATE_H
 
+#include <datatypes.h>
+
 /**
  * Part of this structure has been commented because the corresponding
  * functionality is not yet implemented.
@@ -37,8 +39,8 @@ typedef struct state_t {
     //time_t tx_status_tv;
     //bool tx_status;
     
-    //freq_t rx_freq;
-    //freq_t tx_freq;
+    freq_t rx_freq;
+    freq_t tx_freq;
     
     //float tx_power;
     
diff --git a/openrtx/src/main.c b/openrtx/src/main.c
index 0fc4d8c7..26b2ab36 100644
--- a/openrtx/src/main.c
+++ b/openrtx/src/main.c
@@ -33,6 +33,9 @@ int main(void)
 {
     OS_ERR os_err;
 
+    // Initialize the radio state
+    state_init();
+    
     // Init the graphic stack
     gfx_init();
     platform_setBacklightLevel(255);
@@ -52,7 +55,6 @@ int main(void)
     gfx_render();
     while(gfx_renderingInProgress());
 
-
     // UI update infinite loop
     while(1)
     {
diff --git a/openrtx/src/state.c b/openrtx/src/state.c
index bfe6a8fe..378efea3 100644
--- a/openrtx/src/state.c
+++ b/openrtx/src/state.c
@@ -24,6 +24,10 @@ state_t current_state;
 
 void state_init()
 {
+    /*TODO: Read current state parameters from hardware, 
+     * or initialize them to sane defaults */
+     current_state.rx_freq = 0.0;
+     current_state.tx_freq = 0.0;
 }
 
 state_t state_update()
diff --git a/openrtx/src/ui.c b/openrtx/src/ui.c
index 533162e7..1af4e0b1 100644
--- a/openrtx/src/ui.c
+++ b/openrtx/src/ui.c
@@ -77,13 +77,29 @@ void ui_drawTopBar()
     // TODO: Replace with battery icon
     char bat_buf[6] = "";
     float v_bat = platform_getVbat();
-    snprintf(bat_buf, sizeof(bat_buf), "%.1fV", v_bat);
+    snprintf(bat_buf, sizeof(bat_buf), "%.1fV ", v_bat);
     gfx_print(top_bar_pos, bat_buf, FONT_SIZE_1, TEXT_ALIGN_RIGHT, color_white);
 }
 
-void ui_drawMainScreen()
+void ui_drawVFO(state_t state)
+{
+    // Middle line printing positions, uses 8 px padding
+    point_t line1_pos = {0, 25};
+    point_t line2_pos = {0, 57};
+    point_t line3_pos = {0, 89};
+
+    // Print VFO frequencies
+    char freq_buf[20] = "";
+    snprintf(freq_buf, sizeof(freq_buf), "Rx: %09.5f", state.rx_freq);
+    gfx_print(line1_pos, freq_buf, FONT_SIZE_3, TEXT_ALIGN_CENTER, color_white);
+    snprintf(freq_buf, sizeof(freq_buf), "Tx: %09.5f", state.tx_freq);
+    gfx_print(line2_pos, freq_buf, FONT_SIZE_3, TEXT_ALIGN_CENTER, color_white);
+}
+
+void ui_drawMainScreen(state_t state)
 {
     ui_drawTopBar();
+    ui_drawVFO(state);
 }
 
 void ui_init()
@@ -93,7 +109,7 @@ void ui_init()
 bool ui_update(state_t state, uint32_t keys)
 {
     gfx_clearScreen();
-    ui_drawMainScreen();
+    ui_drawMainScreen(state);
     return true;
 }