diff --git a/device.h b/device.h
index c26447a..2c0ab1a 100644
--- a/device.h
+++ b/device.h
@@ -38,8 +38,17 @@
     #define DAC_DDR  DDRD
     #define LED_PORT PORTB
     #define LED_DDR  DDRB
+    #define PTT_PORT PORTD
+    #define PTT_DDR  DDRD
     #define ADC_PORT PORTC
     #define ADC_DDR  DDRC
+    // Pins 3-7 on Port D = Arduino D3 - D7
+    #define DAC_HIGH _BV(7)
+    #define DAC_PINS _BV(7)&_BV(6)&_BV(5)&_BV(4)
+    #define LED_TX   1    // Arduino D9
+    #define LED_RX   2    // Arduino D10
+    #define PTT_TX   3    // Arduino D11
+    #define ADC_NO   0    // Arduino A0
 #endif
 
-#endif
\ No newline at end of file
+#endif
diff --git a/hardware/AFSK.c b/hardware/AFSK.c
index 05f89e7..b43613c 100644
--- a/hardware/AFSK.c
+++ b/hardware/AFSK.c
@@ -38,9 +38,9 @@ void AFSK_hw_init(void) {
         ADMUX = 0;
     }
 
-    ADC_DDR  &= ~_BV(0);
-    ADC_PORT &= ~_BV(0);
-    DIDR0 |= _BV(0);
+    ADC_DDR  &= ~_BV(ADC_NO);
+    ADC_PORT &= ~_BV(ADC_NO);
+    DIDR0 |= _BV(ADC_NO);
     ADCSRB =    _BV(ADTS2) |
                 _BV(ADTS1) |
                 _BV(ADTS0);  
@@ -51,6 +51,7 @@ void AFSK_hw_init(void) {
                 _BV(ADPS2);
 
     AFSK_DAC_INIT();
+    PTT_INIT();
     LED_TX_INIT();
     LED_RX_INIT();
 }
@@ -84,6 +85,7 @@ static void AFSK_txStart(Afsk *afsk) {
         afsk->phaseAcc = 0;
         afsk->bitstuffCount = 0;
         afsk->sending = true;
+        PTT_TX_ON();
         LED_TX_ON();
         afsk->preambleLength = DIV_ROUND(custom_preamble * BITRATE, 8000);
         AFSK_DAC_IRQ_START();
@@ -121,6 +123,7 @@ uint8_t AFSK_dac_isr(Afsk *afsk) {
             if (fifo_isempty(&afsk->txFifo) && afsk->tailLength == 0) {
                 AFSK_DAC_IRQ_STOP();
                 afsk->sending = false;
+                PTT_TX_OFF();
                 LED_TX_OFF();
                 return 0;
             } else {
@@ -141,6 +144,7 @@ uint8_t AFSK_dac_isr(Afsk *afsk) {
                     if (fifo_isempty(&afsk->txFifo)) {
                         AFSK_DAC_IRQ_STOP();
                         afsk->sending = false;
+                        PTT_TX_OFF();
                         LED_TX_OFF();
                         return 0;
                     } else {
@@ -499,9 +503,12 @@ ISR(ADC_vect) {
     TIFR1 = _BV(ICF1);
     AFSK_adc_isr(AFSK_modem, ((int16_t)((ADC) >> 2) - 128));
     if (hw_afsk_dac_isr) {
-        DAC_PORT = (AFSK_dac_isr(AFSK_modem) & 0xF0) | _BV(3); 
+        // Set DAC pin(s) according to position in SIN wave.
+        DAC_PORT |= (AFSK_dac_isr(AFSK_modem) & DAC_PINS);
     } else {
-        DAC_PORT = 128;
+        // Set DAC pin(s) to the zero point in the SIN wave.
+        // This is represented by setting only the high-bit.
+        DAC_PORT = (DAC_PORT & (~DAC_PINS)) | DAC_HIGH;
     }
     ++_clock;
-}
\ No newline at end of file
+}
diff --git a/hardware/AFSK.h b/hardware/AFSK.h
index cd2fc92..d5440f3 100644
--- a/hardware/AFSK.h
+++ b/hardware/AFSK.h
@@ -142,23 +142,30 @@ typedef struct Afsk
 
 #define AFSK_DAC_IRQ_START()   do { extern bool hw_afsk_dac_isr; hw_afsk_dac_isr = true; } while (0)
 #define AFSK_DAC_IRQ_STOP()    do { extern bool hw_afsk_dac_isr; hw_afsk_dac_isr = false; } while (0)
-#define AFSK_DAC_INIT()        do { DAC_DDR |= 0xF8; } while (0)
+// DAC_PINS equals b11111000 which on port D on Arduino sets D3, D4, D5, D6, D7
+// to be outputs.
+#define AFSK_DAC_INIT()        do { DAC_DDR |= DAC_PINS; } while (0)
 
 // Here's some macros for controlling the RX/TX LEDs
 // THE _INIT() functions writes to the DDRB register
 // to configure the pins as output pins, and the _ON()
 // and _OFF() functions writes to the PORT registers
 // to turn the pins on or off.
-#define LED_TX_INIT() do { LED_DDR |= _BV(1); } while (0)
-#define LED_TX_ON()   do { LED_PORT |= _BV(1); } while (0)
-#define LED_TX_OFF()  do { LED_PORT &= ~_BV(1); } while (0)
+#define LED_TX_INIT() do { LED_DDR |= _BV(LED_TX); } while (0)
+#define LED_TX_ON()   do { LED_PORT |= _BV(LED_TX); } while (0)
+#define LED_TX_OFF()  do { LED_PORT &= ~_BV(LED_TX); } while (0)
 
-#define LED_RX_INIT() do { LED_DDR |= _BV(2); } while (0)
-#define LED_RX_ON()   do { LED_PORT |= _BV(2); } while (0)
-#define LED_RX_OFF()  do { LED_PORT &= ~_BV(2); } while (0)
+#define LED_RX_INIT() do { LED_DDR |= _BV(LED_RX); } while (0)
+#define LED_RX_ON()   do { LED_PORT |= _BV(LED_RX); } while (0)
+#define LED_RX_OFF()  do { LED_PORT &= ~_BV(LED_RX); } while (0)
+
+// Along the same lines, these initialize and control the PTT signal
+#define PTT_INIT()    do { PTT_DDR |= _BV(PTT_TX); } while (0)
+#define PTT_TX_ON()   do { PTT_PORT |= _BV(PTT_TX); } while (0)
+#define PTT_TX_OFF()  do { PTT_PORT &= ~_BV(PTT_TX); } while (0)
 
 void AFSK_init(Afsk *afsk);
 void AFSK_transmit(char *buffer, size_t size);
 void AFSK_poll(Afsk *afsk);
 
-#endif
\ No newline at end of file
+#endif