add pico_dds for CW ID

cubesatsim/cubesatsim.ino

@@ -3841,6 +3841,10 @@ void transmit_cw(int freq, float duration) {  // freq in Hz, duration in millise
 	
   unsigned long start = micros();
   unsigned long duration_us = duration * 1000;
+  dds_setfreq(freq);
+  sleep(duration_us);
+  dds_setfreq(0);
+/*	
   float period_us = (0.5E6) / (float)(freq);
   bool phase = HIGH;	
   while((micros() - start) < duration_us)  {
@@ -3849,6 +3853,7 @@ void transmit_cw(int freq, float duration) {  // freq in Hz, duration in millise
     float time_left = (float)(start + duration_us - micros());	  
     sleep(min(time_left, period_us) / 1.0E6);  
   }
+*/
   digitalWrite(AUDIO_OUT_PIN, LOW);	
 //  if (!wifi) 
   digitalWrite(LED_BUILTIN, LOW);	// Transmit LED off