diff --git a/meson.build b/meson.build
index 478ac40e..f2dc1d59 100644
--- a/meson.build
+++ b/meson.build
@@ -5,6 +5,12 @@ project('OpenRTX', ['c', 'cpp'],
   version : '0.3.1',
   default_options : ['warning_level=3'])
 
+##
+## Optional defines, common to all souces (e.g. to enable debugging)
+##
+
+def = { }
+
 ##
 ## ----------------- Platform-independent source files -------------------------
 ##
@@ -71,7 +77,7 @@ rtos_inc = ['lib/miosix-kernel',
 
 src = openrtx_src + minmea_src
 inc = openrtx_inc + rtos_inc + minmea_inc + qdec_inc
-def = {'DONT_USE_CMSIS_INIT': ''}
+def = def + {'DONT_USE_CMSIS_INIT': ''}
 
 ## Add git commit or tag to print in OpenRTX
 r = run_command('git', 'describe', '--tags', '--dirty')
diff --git a/platform/drivers/audio/audio_MDx.c b/platform/drivers/audio/audio_MDx.c
index 86ce780d..4e610a07 100644
--- a/platform/drivers/audio/audio_MDx.c
+++ b/platform/drivers/audio/audio_MDx.c
@@ -28,14 +28,18 @@ void audio_init()
     gpio_setMode(SPK_MUTE,     OUTPUT);
     #ifndef PLATFORM_MD9600
     gpio_setMode(AUDIO_AMP_EN, OUTPUT);
+    #ifndef MDx_ENABLE_SWD
     gpio_setMode(MIC_PWR,      OUTPUT);
     #endif
+    #endif
 
     gpio_setPin(SPK_MUTE);          /* Speaker muted   */
     #ifndef PLATFORM_MD9600
     gpio_clearPin(AUDIO_AMP_EN);    /* Audio PA off    */
+    #ifndef MDx_ENABLE_SWD
     gpio_clearPin(MIC_PWR);         /* Mic preamp. off */
     #endif
+    #endif
 }
 
 void audio_terminate()
@@ -43,20 +47,22 @@ void audio_terminate()
     gpio_setPin(SPK_MUTE);          /* Speaker muted   */
     #ifndef PLATFORM_MD9600
     gpio_clearPin(AUDIO_AMP_EN);    /* Audio PA off    */
+    #ifndef MDx_ENABLE_SWD
     gpio_clearPin(MIC_PWR);         /* Mic preamp. off */
     #endif
+    #endif
 }
 
 void audio_enableMic()
 {
-    #ifndef PLATFORM_MD9600
+    #if !defined(PLATFORM_MD9600) && !defined(MDx_ENABLE_SWD)
     gpio_setPin(MIC_PWR);
     #endif
 }
 
 void audio_disableMic()
 {
-    #ifndef PLATFORM_MD9600
+    #if !defined(PLATFORM_MD9600) && !defined(MDx_ENABLE_SWD)
     gpio_clearPin(MIC_PWR);
     #endif
 }
diff --git a/platform/drivers/baseband/radio_MD3x0.cpp b/platform/drivers/baseband/radio_MD3x0.cpp
index 30a5ca1e..ca8c3f62 100644
--- a/platform/drivers/baseband/radio_MD3x0.cpp
+++ b/platform/drivers/baseband/radio_MD3x0.cpp
@@ -61,17 +61,23 @@ void _setBandwidth(const enum bandwidth bw)
     switch(bw)
     {
         case BW_12_5:
+            #ifndef MDx_ENABLE_SWD
             gpio_clearPin(WN_SW);
+            #endif
             C5000.setModFactor(0x1E);
             break;
 
         case BW_20:
+            #ifndef MDx_ENABLE_SWD
             gpio_setPin(WN_SW);
+            #endif
             C5000.setModFactor(0x30);
             break;
 
         case BW_25:
+            #ifndef MDx_ENABLE_SWD
             gpio_setPin(WN_SW);
+            #endif
             C5000.setModFactor(0x3C);
             break;
 
@@ -97,7 +103,9 @@ void radio_init(const rtxStatus_t *rtxState)
     gpio_setMode(PLL_PWR,   OUTPUT);
     gpio_setMode(VCOVCC_SW, OUTPUT);
     gpio_setMode(DMR_SW,    OUTPUT);
+    #ifndef MDx_ENABLE_SWD
     gpio_setMode(WN_SW,     OUTPUT);
+    #endif
     gpio_setMode(FM_SW,     OUTPUT);
     gpio_setMode(RF_APC_SW, OUTPUT);
     gpio_setMode(TX_STG_EN, OUTPUT);
@@ -108,7 +116,9 @@ void radio_init(const rtxStatus_t *rtxState)
 
     gpio_clearPin(PLL_PWR);    // PLL off
     gpio_setPin(VCOVCC_SW);    // VCOVCC high enables RX VCO, TX VCO if low
+    #ifndef MDx_ENABLE_SWD
     gpio_setPin(WN_SW);        // 25kHz bandwidth
+    #endif
     gpio_clearPin(DMR_SW);     // Disconnect HR_C5000 input IF signal and audio out
     gpio_clearPin(FM_SW);      // Disconnect analog FM audio path
     gpio_clearPin(RF_APC_SW);  // Disable TX power control
diff --git a/platform/mcu/STM32F4xx/boot/bsp.cpp b/platform/mcu/STM32F4xx/boot/bsp.cpp
index 51da8938..33d471eb 100644
--- a/platform/mcu/STM32F4xx/boot/bsp.cpp
+++ b/platform/mcu/STM32F4xx/boot/bsp.cpp
@@ -52,6 +52,18 @@ void IRQbspInit()
     GPIOE->OSPEEDR=0xaaaaaaaa;
     GPIOH->OSPEEDR=0xaaaaaaaa;
 
+    /*
+     * Enable SWD interface on PA13 and PA14 (Tytera's bootloader disables this
+     * functionality).
+     * NOTE: these pins are used also for other functions (MIC power and wide/
+     * narrow FM reception), thus they cannot be always used for debugging!
+     */
+    #ifdef MDx_ENABLE_SWD
+    GPIOA->MODER  &= ~0x3C000000;   // Clear current setting
+    GPIOA->MODER  |= 0x28000000;    // Put back to alternate function
+    GPIOA->AFR[1] &= ~0x0FF00000;   // SWD is AF0
+    #endif
+
     #ifdef MD3x0_ENABLE_DBG
     usart3_init(115200);
     usart3_IRQwrite("starting...\r\n");