Implemented reading of PTT status from external microphone on MD-3x0 and MD-UV3x0

platform/targets/MD-3x0/hwconfig.h

@@ -80,7 +80,8 @@
 #define CH_SELECTOR_3 GPIOB,11
 
 /* Push-to-talk switch */
-#define PTT_SW GPIOE,11
+#define PTT_SW  GPIOE,11
+#define PTT_EXT GPIOE,12
 
 /*
  * Keyboard. Here we define only rows, since coloumn lines are the same as

platform/targets/MD-3x0/platform.c

@@ -46,7 +46,8 @@ void platform_init()
     gpio_setMode(CH_SELECTOR_2, INPUT);
     gpio_setMode(CH_SELECTOR_3, INPUT);
 
-    gpio_setMode(PTT_SW, INPUT);
+    gpio_setMode(PTT_SW,  INPUT);
+    gpio_setMode(PTT_EXT, INPUT);
 
     gpio_setMode(PWR_SW, OUTPUT);
 
@@ -122,7 +123,9 @@ int8_t platform_getChSelector()
 bool platform_getPttStatus()
 {
     /* PTT line has a pullup resistor with PTT switch closing to ground */
-    return (gpio_readPin(PTT_SW) == 0) ? true : false;
+    uint8_t intPttStatus = gpio_readPin(PTT_SW);
+    uint8_t extPttStatus = gpio_readPin(PTT_EXT);
+    return ((intPttStatus == 0) || (extPttStatus == 0)) ? true : false;
 }
 
 bool platform_pwrButtonStatus()

platform/targets/MD-UV3x0/hwconfig.h

@@ -74,7 +74,8 @@
 #define CH_SELECTOR_1 GPIOB,11
 
 /* Push-to-talk switch */
-#define PTT_SW GPIOE,11
+#define PTT_SW  GPIOE,11
+#define PTT_EXT GPIOE,12
 
 /*
  * Keyboard. Here we define only rows, since coloumn lines are the same as

platform/targets/MD-UV3x0/platform.c

@@ -43,7 +43,8 @@ void platform_init()
 
     gpio_setMode(PTT_SW, INPUT_PULL_UP);
 
-    gpio_setMode(PWR_SW, OUTPUT);
+    gpio_setMode(PTT_SW,  INPUT);
+    gpio_setMode(PTT_EXT, INPUT);
 
     /*
      * Initialise ADC1, for vbat, RSSI, ...
@@ -116,7 +117,9 @@ float platform_getVolumeLevel()
 bool platform_getPttStatus()
 {
     /* PTT line has a pullup resistor with PTT switch closing to ground */
-    return (gpio_readPin(PTT_SW) == 0) ? true : false;
+    uint8_t intPttStatus = gpio_readPin(PTT_SW);
+    uint8_t extPttStatus = gpio_readPin(PTT_EXT);
+    return ((intPttStatus == 0) || (extPttStatus == 0)) ? true : false;
 }
 
 bool platform_pwrButtonStatus()