diff --git a/platformio.ini b/platformio.ini
index db4748c..af4439d 100644
--- a/platformio.ini
+++ b/platformio.ini
@@ -8,15 +8,18 @@
 ; Please visit documentation for the other options and examples
 ; https://docs.platformio.org/page/projectconf.html
 
-[env:d1_mini_pro]
-platform = espressif8266
-board = d1_mini_pro
-framework = arduino
+[platformio]
+env_default = heltec_wifi_kit_8
 
 [env:heltec_wifi_kit_8]
 platform = espressif8266
 board = heltec_wifi_kit_8
 framework = arduino
 
+[env:d1_mini_pro]
+platform = espressif8266
+board = d1_mini_pro
+framework = arduino
+
 [lib_deps]
 library = WifiManager, RF24, U8g2
diff --git a/src/clockMsg.h b/src/clockMsg.h
new file mode 100644
index 0000000..af430d3
--- /dev/null
+++ b/src/clockMsg.h
@@ -0,0 +1,14 @@
+#ifndef clockMsg_h_included
+#define clockMsg_h_included
+
+#include <Arduino.h>
+
+struct clockMsg_s {
+  uint8_t msgType;
+  uint8_t hour;
+  uint8_t minute;
+  uint8_t second;
+};
+#define msgType_Clock 'c'
+
+#endif
diff --git a/src/display.cpp b/src/display.cpp
index 540b665..501e8bb 100644
--- a/src/display.cpp
+++ b/src/display.cpp
@@ -4,7 +4,6 @@
 
 #include "display.h"
 
-
 // display
 //U8G2_SSD1306_128X32_UNIVISION_F_HW_I2C u8g2(U8G2_R0, /* reset=*/ 16, /* clock=*/ 5, /* data=*/ 4);
 U8G2_SSD1306_128X32_UNIVISION_F_HW_I2C u8g2(U8G2_R0, /* reset=16*/ -1, /* clock=*/ 5, /* data=*/ 4);
diff --git a/src/fastclock.cpp b/src/fastclock.cpp
index 2bc24aa..c4bc69d 100644
--- a/src/fastclock.cpp
+++ b/src/fastclock.cpp
@@ -67,6 +67,7 @@ void Fastclock::loop(void) {
     // time has changed, send an update via rf
     // @TODO implement sending radio message
     Serial.println("Would send new time");
+    radio->broadcastClock(hour, minute, second);
   }
 }
 
diff --git a/src/fastclock.h b/src/fastclock.h
index e9d0778..563e58d 100644
--- a/src/fastclock.h
+++ b/src/fastclock.h
@@ -2,13 +2,14 @@
 #define fastclock_h_included
 
 #include "display.h"
+#include "radio.h"
 
 #define MIN_TIME_ms_BETWEEN_CLOCK_UPDATES 200
 #define DEFAULT_ms_PER_MODEL_SECOND 250
 
 class Fastclock {
 public:
-  Fastclock(Display *d): display(d) { weekday=0; hour=0; minute=0; second=0; millisecond=0; msPerModelSecond=DEFAULT_ms_PER_MODEL_SECOND; halted = true; };
+  Fastclock(Display *d, Radio *r): display(d), radio(r) { weekday=0; hour=0; minute=0; second=0; millisecond=0; msPerModelSecond=DEFAULT_ms_PER_MODEL_SECOND; halted = true; };
   void begin(void);
   void loop(void);
   void incrementClockByMilliseconds(int amount);
@@ -20,6 +21,7 @@ public:
   void setClockHalted(bool setToHalt) { halted = setToHalt; display->setClockHalted(halted); };
 private:
   Display *display;
+  Radio *radio;
   unsigned long lastTimeTickUsed; // used to calculate model time
   unsigned long msPerModelSecond; // 500 = twice as fast as real time
   uint8_t weekday;
diff --git a/src/main.cpp b/src/main.cpp
index 154b1e3..1e2f151 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -34,8 +34,8 @@ bool shouldSaveConfig = false;
 bool isMaster = true;
 
 Display display;
-Fastclock fastclock(&display);
 Radio radio(&display, true /*isMaster*/);
+Fastclock fastclock(&display, &radio);
 
 //callback notifying us of the need to save config
 void saveConfigCallback () {
diff --git a/src/radio.cpp b/src/radio.cpp
index 5a1f4c6..37eff42 100644
--- a/src/radio.cpp
+++ b/src/radio.cpp
@@ -3,6 +3,8 @@
 #include <RF24.h>
 #include "config.h"
 #include "radio.h"
+#include "clockMsg.h"
+
 
 static RF24 rf24(PIN_NRF24_CE, PIN_NRF24_CSN); // 10, 8
 static byte addresses[][6] = {NETWORK_ADDRESS_MASTER_SEND, NETWORK_ADDRESS_MASTER_RECEIVE};
@@ -11,7 +13,7 @@ void Radio::begin(void) {
   display->addLogMessage("Start RF24 radio");
   pinMode(PIN_NRF24_CSN, OUTPUT);
   pinMode(PIN_NRF24_CE, OUTPUT);
-  return;
+
   rf24.begin();
   if (rf24.isChipConnected()) { display->addLogMessage("*** RF chip found"); }
   else { display->addLogMessage("*** ERROR: RF chip not found!"); }
@@ -24,11 +26,12 @@ void Radio::begin(void) {
   rf24.openWritingPipe(addresses[0]);
   rf24.openReadingPipe(1, addresses[1]);
   rf24.startListening();
-  rf24.printDetails();
+  Serial.println("*** Check");
+  //rf24.printDetails();
+  rf24.powerUp();
   // @TODO: real random seed!
   //randomSeed(analogRead(0));
   //randomSeed(22);
-  rf24.powerUp();
   Serial.print("*** RF payload size="); Serial.print(rf24.getPayloadSize()); Serial.println(" bytes");
   if (rf24.testCarrier() || rf24.testRPD()) { display->addLogMessage("*** Carrier/RPD seen on radio"); }
   if (rf24.failureDetected) { display->addLogMessage("*** Radio error detected!"); }
@@ -50,57 +53,80 @@ void Radio::begin(void) {
   rf24.startListening();
 }
 
+static bool inTX=1, inRX=0, role=inRX;
+
+static void switchToSenderRole(RF24 radio)
+{
+  Serial.println("*** master: CHANGING TO TRANSMIT ROLE");
+  radio.openWritingPipe(addresses[1]);
+  radio.openReadingPipe(1,addresses[0]);
+  radio.stopListening();
+  role = inTX;                  // Become the primary transmitter (ping out)
+}
+
+static void switchToReceiverRole(RF24 radio)
+{
+  Serial.println("*** master: CHANGING TO RECEIVER ROLE");
+  radio.openWritingPipe(addresses[0]);
+  radio.openReadingPipe(1,addresses[1]);
+  radio.startListening();
+  role = inRX;                // Become the primary receiver (pong back)
+}
+
+static int sendFailedCounter = 0;
+static unsigned long stopTime = 0, pauseTime = 0;
+
+void Radio::broadcastClock(int hour, int minute, int second) {
+  struct clockMsg_s clockMsg;
+
+  clockMsg.msgType = msgType_Clock;
+  clockMsg.hour = hour;
+  clockMsg.minute = minute;
+  clockMsg.second = second;
+  switchToSenderRole(rf24);
+  if (!rf24.write(&clockMsg, sizeof(clockMsg), true /*multicast*/)) {
+      sendFailedCounter++;
+      Serial.print("*** ERROR: failed to send clock msg for "); Serial.print(hour); Serial.print(":"); Serial.print(minute); Serial.print(":"); Serial.println(second);
+  }
+  //This is only required when NO ACK ( enableAutoAck(0) ) payloads are used
+  if (millis() - pauseTime > 3) {
+    pauseTime = millis();
+    rf24.txStandBy();          // Need to drop out of TX mode every 4ms if sending a steady stream of multicast data
+    //delayMicroseconds(130);     // This gives the PLL time to sync back up
+  }
+  stopTime = millis();
+                                      //This should be called to wait for completion and put the radio in standby mode after transmission, returns 0 if data still in FIFO (timed out), 1 if success
+  if (!rf24.txStandBy()) { sendFailedCounter += 3; } //Standby, block only until FIFO empty or auto-retry timeout. Flush TX FIFO if failed
+  //radio.txStandBy(1000);              //Standby, using extended timeout period of 1 second
+
+  Serial.print("*** send finished, fail-counter="); Serial.println(sendFailedCounter);
+}
 
 void Radio::loop(void) {
-  #if 0
   // put your main code here, to run repeatedly:
   /****************** Ping Out Role ***************************/
   if (isMaster)  {
+    switchToReceiverRole(rf24);
+    if (rf24.available()) {
+      struct clockMsg_s clockMsg;
+      rf24.read(&clockMsg, sizeof(struct clockMsg_s));
 
-      radio.stopListening();
-
-      Serial.println(F("Now sending"));
-
-      unsigned long start_time = micros();
-       if (!radio.write(&start_time, sizeof(unsigned long))) {
-         Serial.println(F("failed"));
-       }
-
-      radio.startListening();
-
-      unsigned long started_waiting_at = micros();
-      boolean timeout = false;
-
-      while (!radio.available()) {
-        if (micros() - started_waiting_at > 200000 ) {            // If waited longer than 200ms, indicate timeout and exit while loop
-            timeout = true;
-            break;
-        }
-      }
-
-      if (timeout) {
-          Serial.println(F("Failed, response timed out."));
-      } else {
-          unsigned long got_time;
-          radio.read( &got_time, sizeof(unsigned long) );
-          unsigned long end_time = micros();
-
-          // Spew it
-          Serial.print(F("Sent "));
-          Serial.print(start_time);
-          Serial.print(F(", Got response "));
-          Serial.print(got_time);
-          Serial.print(F(", Round-trip delay "));
-          Serial.print(end_time-start_time);
-          Serial.println(F(" microseconds"));
-      }
-
-      // Try again 1s later
-      delay(1000);
+      // Spew it
+      Serial.print(F("Received clock message, type="));
+      Serial.print(clockMsg.msgType);
+      Serial.print(F(", time="));
+      Serial.print(clockMsg.hour);
+      Serial.print(":");
+      Serial.print(clockMsg.minute);
+      Serial.print(":");
+      Serial.println(clockMsg.second);
     }
+  }
 
 
 
+    #if 0
+
   /****************** Pong Back Role ***************************/
 
     if (!isMaster)
diff --git a/src/radio.h b/src/radio.h
index 2cf0c5f..c35c57e 100644
--- a/src/radio.h
+++ b/src/radio.h
@@ -8,6 +8,7 @@ public:
   Radio(Display *d, bool _isMaster):display(d), isMaster(_isMaster) { };
   void begin(void);
   void loop(void);
+  void broadcastClock(int hour, int minute, int second);
 private:
   Display *display;
   bool isMaster;