diff --git a/flight/PipXtreme/Makefile b/flight/PipXtreme/Makefile
index 0dc7b8e2a..b05faff07 100644
--- a/flight/PipXtreme/Makefile
+++ b/flight/PipXtreme/Makefile
@@ -129,6 +129,7 @@ SRC += $(PIOSSTM32F10X)/pios_irq.c
 SRC += $(PIOSSTM32F10X)/pios_adc.c
 SRC += $(PIOSSTM32F10X)/pios_gpio.c
 SRC += $(PIOSSTM32F10X)/pios_spi.c
+SRC += $(PIOSSTM32F10X)/pios_ppm.c
 
 # PIOS USB related files (seperated to make code maintenance more easy)
 ifeq ($(USE_USB), YES)
diff --git a/flight/PipXtreme/api_config.c b/flight/PipXtreme/api_config.c
index 15bb173ad..201d8f8b3 100644
--- a/flight/PipXtreme/api_config.c
+++ b/flight/PipXtreme/api_config.c
@@ -30,6 +30,8 @@
 #include "api_config.h"
 #include "rfm22b.h"
 #include "packet_handler.h"
+#include "stream.h"
+#include "ppm.h"
 #include "saved_settings.h"
 #include "crc.h"
 #include "main.h"
@@ -344,6 +346,8 @@ void apiconfig_processInputPacket(void *buf, uint16_t len)
 			if (header->serial_number == serial_number_crc32)
 			{	// the packet is meant for us
 
+				booting = true;
+
 			    ph_set_remote_serial_number(0, 0);	// stop the packet handler trying to communicate
 
 			    // ******
@@ -384,59 +388,53 @@ void apiconfig_processInputPacket(void *buf, uint16_t len)
 			    		break;
 			    }
 
-			    if (saved_settings.mode != MODE_SCAN_SPECTRUM)
-			    {
-			    	if (saved_settings.mode == MODE_STREAM_TX || saved_settings.mode == MODE_PPM_TX)
-			    		rfm22_init_tx_stream(saved_settings.min_frequency_Hz, saved_settings.max_frequency_Hz);
-			    	else
-			    	if (saved_settings.mode == MODE_STREAM_RX || saved_settings.mode == MODE_PPM_RX)
-			    		rfm22_init_rx_stream(saved_settings.min_frequency_Hz, saved_settings.max_frequency_Hz);
-			    	else
-			    		rfm22_init_normal(saved_settings.min_frequency_Hz, saved_settings.max_frequency_Hz, rfm22_freqHopSize());
-
-				    rfm22_setFreqCalibration(saved_settings.rf_xtal_cap);
-				    ph_setNominalCarrierFrequency(saved_settings.frequency_Hz);
-				    ph_setDatarate(saved_settings.max_rf_bandwidth);
-				    ph_setTxPower(saved_settings.max_tx_power);
-
-				    ph_set_remote_encryption(0, saved_settings.aes_enable, (const void *)saved_settings.aes_key);
-				    ph_set_remote_serial_number(0, saved_settings.destination_id);
-			    }
-			    else
-			    {
-					rfm22_init_scan_spectrum(saved_settings.min_frequency_Hz, saved_settings.max_frequency_Hz);
-				    rfm22_setFreqCalibration(saved_settings.rf_xtal_cap);
-			    	apiconfig_spec_start_freq = saved_settings.min_frequency_Hz;
-			    	apiconfig_spec_freq = apiconfig_spec_start_freq;
-			    	apiconfig_spec_buffer_wr = 0;
-			    	apiconfig_ss_timer = 0;
-			    }
-
 			    switch (saved_settings.mode)
 			    {
-			    	case MODE_NORMAL:					// normal 2-way packet mode
+			    	case MODE_NORMAL:						// normal 2-way packet mode
+			   			ph_init(serial_number_crc32);		// initialise the packet handler
 			    		break;
-			    	case MODE_STREAM_TX:				// 1-way continuous tx packet mode
-			    		rfm22_setTxStream();			// TEST ONLY
+
+			    	case MODE_STREAM_TX:					// 1-way continuous tx packet mode
+			    	case MODE_STREAM_RX:					// 1-way continuous rx packet mode
+			   			stream_init(serial_number_crc32);	// initialise the continuous packet stream module
 		    			break;
-			    	case MODE_STREAM_RX:				// 1-way continuous rx packet mode
-		    			break;
-			    	case MODE_PPM_TX:					// PPM tx mode
-			    		rfm22_setTxStream();			// TEST ONLY
-			    		break;
-			    	case MODE_PPM_RX:					// PPM rx mode
+
+			    	case MODE_PPM_TX:						// PPM tx mode
+			    	case MODE_PPM_RX:						// PPM rx mode
+			   			ppm_init(serial_number_crc32);		// initialise the PPM module
 		    			break;
+
 			    	case MODE_SCAN_SPECTRUM:			// scan the receiver over the whole band
+						rfm22_init_scan_spectrum(saved_settings.min_frequency_Hz, saved_settings.max_frequency_Hz);
+					    rfm22_setFreqCalibration(saved_settings.rf_xtal_cap);
+				    	apiconfig_spec_start_freq = saved_settings.min_frequency_Hz;
+				    	apiconfig_spec_freq = apiconfig_spec_start_freq;
+				    	apiconfig_spec_buffer_wr = 0;
+				    	apiconfig_ss_timer = 0;
 			    		break;
+
 			    	case MODE_TX_BLANK_CARRIER_TEST:	// blank carrier Tx mode (for calibrating the carrier frequency say)
+			    		rfm22_init_normal(saved_settings.min_frequency_Hz, saved_settings.max_frequency_Hz, rfm22_freqHopSize());
+			    	    rfm22_setFreqCalibration(saved_settings.rf_xtal_cap);
+			    	    rfm22_setNominalCarrierFrequency(saved_settings.frequency_Hz);
+			    	    rfm22_setDatarate(saved_settings.max_rf_bandwidth, TRUE);
+			    	    rfm22_setTxPower(saved_settings.max_tx_power);
 			    		rfm22_setTxCarrierMode();
 			    		break;
+
 			    	case MODE_TX_SPECTRUM_TEST:			// pseudo random Tx data mode (for checking the Tx carrier spectrum)
+			    		rfm22_init_normal(saved_settings.min_frequency_Hz, saved_settings.max_frequency_Hz, rfm22_freqHopSize());
+			    	    rfm22_setFreqCalibration(saved_settings.rf_xtal_cap);
+			    	    rfm22_setNominalCarrierFrequency(saved_settings.frequency_Hz);
+			    	    rfm22_setDatarate(saved_settings.max_rf_bandwidth, TRUE);
+			    	    rfm22_setTxPower(saved_settings.max_tx_power);
 			    		rfm22_setTxPNMode();
 			    		break;
 			    }
 
 			    // ******
+
+			    booting = false;
 			}
 
 			break;
diff --git a/flight/PipXtreme/inc/packet_handler.h b/flight/PipXtreme/inc/packet_handler.h
index 9f7c9a163..694d21cd6 100644
--- a/flight/PipXtreme/inc/packet_handler.h
+++ b/flight/PipXtreme/inc/packet_handler.h
@@ -68,7 +68,7 @@ void ph_set_AES128_key(const void *key);
 int ph_set_remote_serial_number(int connection_index, uint32_t sn);
 void ph_set_remote_encryption(int connection_index, bool enabled, const void *key);
 
-void ph_init(uint32_t our_sn, uint32_t datarate_bps, uint8_t tx_power);
+void ph_init(uint32_t our_sn);
 
 // *****************************************************************************
 
diff --git a/flight/PipXtreme/inc/pios_config.h b/flight/PipXtreme/inc/pios_config.h
index 7fac02079..f29822eab 100644
--- a/flight/PipXtreme/inc/pios_config.h
+++ b/flight/PipXtreme/inc/pios_config.h
@@ -40,5 +40,6 @@
 #define PIOS_INCLUDE_GPIO
 #define PIOS_INCLUDE_EXTI
 #define PIOS_INCLUDE_USB_HID
+//#define PIOS_INCLUDE_PPM
 
 #endif /* PIOS_CONFIG_H */
diff --git a/flight/PipXtreme/inc/ppm.h b/flight/PipXtreme/inc/ppm.h
index ead92b434..48a3b9aa1 100644
--- a/flight/PipXtreme/inc/ppm.h
+++ b/flight/PipXtreme/inc/ppm.h
@@ -32,7 +32,7 @@
 
 void ppm_1ms_tick(void);
 void ppm_process(void);
-void ppm_init(void);
+void ppm_init(uint32_t our_sn);
 
 // *************************************************************
 
diff --git a/flight/PipXtreme/inc/rfm22b.h b/flight/PipXtreme/inc/rfm22b.h
index b450cdb11..351f02874 100644
--- a/flight/PipXtreme/inc/rfm22b.h
+++ b/flight/PipXtreme/inc/rfm22b.h
@@ -575,7 +575,8 @@ enum {	RX_SCAN_SPECTRUM = 0,
 
 // ************************************
 
-typedef void ( *t_rfm22_TxDataCallback ) (uint8_t *data, uint16_t len);
+typedef int16_t ( *t_rfm22_TxDataByteCallback ) (void);
+typedef bool ( *t_rfm22_RxDataByteCallback ) (uint8_t b);
 
 // ************************************
 
@@ -629,7 +630,8 @@ bool rfm22_txReady(void);
 void rfm22_1ms_tick(void);
 void rfm22_process(void);
 
-void rfm22_TxData_SetCallback(t_rfm22_TxDataCallback new_function);
+void rfm22_TxDataByte_SetCallback(t_rfm22_TxDataByteCallback new_function);
+void rfm22_RxDataByte_SetCallback(t_rfm22_RxDataByteCallback new_function);
 
 int rfm22_init_scan_spectrum(uint32_t min_frequency_hz, uint32_t max_frequency_hz);
 int rfm22_init_tx_stream(uint32_t min_frequency_hz, uint32_t max_frequency_hz);
diff --git a/flight/PipXtreme/inc/stream.h b/flight/PipXtreme/inc/stream.h
index 4958216c2..bdb243975 100644
--- a/flight/PipXtreme/inc/stream.h
+++ b/flight/PipXtreme/inc/stream.h
@@ -32,7 +32,7 @@
 
 void stream_1ms_tick(void);
 void stream_process(void);
-void stream_init(void);
+void stream_init(uint32_t our_sn);
 
 // *************************************************************
 
diff --git a/flight/PipXtreme/main.c b/flight/PipXtreme/main.c
index 53d6f9187..a23d5abf1 100644
--- a/flight/PipXtreme/main.c
+++ b/flight/PipXtreme/main.c
@@ -1,3 +1,4 @@
+
 /**
  ******************************************************************************
  *
@@ -391,9 +392,9 @@ void init_RF_module(void)
     }
 
     rfm22_setFreqCalibration(saved_settings.rf_xtal_cap);
-    ph_setNominalCarrierFrequency(saved_settings.frequency_Hz);
-    ph_setDatarate(saved_settings.max_rf_bandwidth);
-    ph_setTxPower(saved_settings.max_tx_power);
+    rfm22_setNominalCarrierFrequency(saved_settings.frequency_Hz);
+    rfm22_setDatarate(saved_settings.max_rf_bandwidth, TRUE);
+    rfm22_setTxPower(saved_settings.max_tx_power);
 }
 
 // *****************************************************************************
@@ -553,12 +554,10 @@ int main()
 
     // *************
 
-    random32 ^= serial_number_crc32;                    // try to randomize the random number
-//      random32 ^= serial_number_crc32 ^ CRC_IDR;      // try to randomize the random number
+    random32 ^= serial_number_crc32;                    // try to randomise the random number
+//      random32 ^= serial_number_crc32 ^ CRC_IDR;      // try to randomise the random number
 
-    ph_init(serial_number_crc32, 128000, 0);            // initialise the packet handler
-
-    trans_init();                                       // initialise the tranparent communications module
+    trans_init();                                       // initialise the transparent communications module
 
 //	api_init();  	  	                                // initialise the API communications module
     apiconfig_init();                                    // initialise the API communications module
@@ -728,41 +727,57 @@ int main()
 
     init_RF_module();	// initialise the RF module
 
-    stream_init();		// initialise the continuous packet stream module
+    // *************
 
-    ppm_init();			// initialise the ppm module
+	#if defined(PIOS_COM_DEBUG)
+    	DEBUG_PRINTF("\r\n");
+    	DEBUG_PRINTF("RF datarate: %dbps\r\n", ph_getDatarate());
+    	DEBUG_PRINTF("RF frequency: %dHz\r\n", rfm22_getNominalCarrierFrequency());
+    	DEBUG_PRINTF("RF TX power: %d\r\n", ph_getTxPower());
 
-    saved_settings_save();
+    	DEBUG_PRINTF("\r\nUnit mode: ");
+    	switch (saved_settings.mode)
+    	{
+    		case MODE_NORMAL:					DEBUG_PRINTF("NORMAL\r\n"); break;
+    		case MODE_STREAM_TX:				DEBUG_PRINTF("STREAM-TX\r\n"); break;
+    		case MODE_STREAM_RX:				DEBUG_PRINTF("STREAM-RX\r\n"); break;
+    		case MODE_PPM_TX:					DEBUG_PRINTF("PPM-TX\r\n"); break;
+    		case MODE_PPM_RX:					DEBUG_PRINTF("PPM-RX\r\n"); break;
+    		case MODE_SCAN_SPECTRUM:			DEBUG_PRINTF("SCAN-SPECTRUM\r\n"); break;
+    		case MODE_TX_BLANK_CARRIER_TEST:	DEBUG_PRINTF("TX-BLANK-CARRIER\r\n"); break;
+    		case MODE_TX_SPECTRUM_TEST:			DEBUG_PRINTF("TX_SPECTRUM\r\n"); break;
+    		default:							DEBUG_PRINTF("UNKNOWN [%u]\r\n", saved_settings.mode); break;
+    	}
+	#endif
 
-    booting = FALSE;
+   	switch (saved_settings.mode)
+   	{
+   		case MODE_NORMAL:
+   			ph_init(serial_number_crc32);            // initialise the packet handler
+   			break;
+
+   		case MODE_STREAM_TX:
+   		case MODE_STREAM_RX:
+   			stream_init(serial_number_crc32);		// initialise the continuous packet stream module
+   			break;
+
+   		case MODE_PPM_TX:
+   		case MODE_PPM_RX:
+   			ppm_init(serial_number_crc32);			// initialise the ppm module
+   			break;
+
+   		case MODE_SCAN_SPECTRUM:
+   		case MODE_TX_BLANK_CARRIER_TEST:
+   		case MODE_TX_SPECTRUM_TEST:
+   			break;
+   	}
 
     // *************
     // Main executive loop
 
-    #if defined(PIOS_COM_DEBUG)
-        DEBUG_PRINTF("\r\n");
-        DEBUG_PRINTF("RF datarate: %dbps\r\n", ph_getDatarate());
-        DEBUG_PRINTF("RF frequency: %dHz\r\n", rfm22_getNominalCarrierFrequency());
-        DEBUG_PRINTF("RF TX power: %d\r\n", ph_getTxPower());
+    saved_settings_save();
 
-        DEBUG_PRINTF("\r\nUnit mode: ");
-        switch (saved_settings.mode)
-        {
-        	case MODE_NORMAL:					DEBUG_PRINTF("NORMAL\r\n"); break;
-        	case MODE_STREAM_TX:				DEBUG_PRINTF("STREAM-TX\r\n"); break;
-        	case MODE_STREAM_RX:				DEBUG_PRINTF("STREAM-RX\r\n"); break;
-        	case MODE_PPM_TX:					DEBUG_PRINTF("PPM-TX\r\n"); break;
-        	case MODE_PPM_RX:					DEBUG_PRINTF("PPM-RX\r\n"); break;
-        	case MODE_SCAN_SPECTRUM:			DEBUG_PRINTF("SCAN-SPECTRUM\r\n"); break;
-        	case MODE_TX_BLANK_CARRIER_TEST:	DEBUG_PRINTF("TX-BLANK-CARRIER\r\n"); break;
-        	case MODE_TX_SPECTRUM_TEST:			DEBUG_PRINTF("TX_SPECTRUM\r\n"); break;
-        	default:							DEBUG_PRINTF("UNKNOWN [%u]\r\n", saved_settings.mode); break;
-        }
-    #endif
-
-    // start a remote connection going to another modem
-    ph_set_remote_encryption(0, saved_settings.aes_enable, (const void *)saved_settings.aes_key);
-    ph_set_remote_serial_number(0, saved_settings.destination_id);
+    booting = FALSE;
 
     for (;;)
     {
diff --git a/flight/PipXtreme/packet_handler.c b/flight/PipXtreme/packet_handler.c
index 28f786666..bc77c344b 100644
--- a/flight/PipXtreme/packet_handler.c
+++ b/flight/PipXtreme/packet_handler.c
@@ -348,10 +348,23 @@ int ph_startConnect(int connection_index, uint32_t sn)
 }
 
 // *****************************************************************************
+// return a byte for the tx packet transmission.
+//
+// return value < 0 if no more bytes available, otherwise return byte to be sent
 
-void rfm22_TxDataCallback(uint8_t *data, uint16_t len)
+int16_t ph_TxDataByteCallback(void)
 {
+	return -1;
+}
 
+// *************************************************************
+// we are being given a received byte
+//
+// return TRUE to continue current packet receive, otherwise return FALSe to halt current packet reception
+
+bool ph_RxDataByteCallback(uint8_t b)
+{
+	return true;
 }
 
 // *****************************************************************************
@@ -1518,8 +1531,6 @@ int ph_set_remote_serial_number(int connection_index, uint32_t sn)
       fifoBuf_init(&conn->tx_fifo_buffer, conn->tx_buffer, PH_FIFO_BUFFER_SIZE);
       fifoBuf_init(&conn->rx_fifo_buffer, conn->rx_buffer, PH_FIFO_BUFFER_SIZE);
 
-      rfm22_TxData_SetCallback(rfm22_TxDataCallback);
-
       return connection_index;
   }
 
@@ -1542,6 +1553,8 @@ void ph_set_remote_encryption(int connection_index, bool enabled, const void *ke
 
 void ph_1ms_tick(void)
 {
+	if (booting) return;
+
 	if (saved_settings.mode == MODE_NORMAL)
 	{
 		// help randomize the encryptor cbc bytes
@@ -1597,6 +1610,8 @@ void ph_1ms_tick(void)
 
 void ph_process(void)
 {
+	if (booting) return;
+
 	if (saved_settings.mode == MODE_NORMAL)
 	{
 		ph_processRxPacket();
@@ -1612,7 +1627,7 @@ void ph_process(void)
 
 // *****************************************************************************
 
-void ph_init(uint32_t our_sn, uint32_t datarate_bps, uint8_t tx_power)
+void ph_init(uint32_t our_sn)
 {
   our_serial_number = our_sn;	// remember our own serial number
 
@@ -1665,20 +1680,33 @@ void ph_init(uint32_t our_sn, uint32_t datarate_bps, uint8_t tx_power)
       conn->rx_afc_Hz = 0;
   }
 
-  ph_setDatarate(datarate_bps);
-
-  ph_setTxPower(tx_power);
-
   // set the AES encryption key using the default AES key
   ph_set_AES128_key(default_aes_key);
 
-  // try too randomize the tx AES CBC bytes
+  // try too randomise the tx AES CBC bytes
   for (uint32_t j = 0, k = 0; j < 123 + (random32 & 1023); j++)
   {
       random32 = updateCRC32(random32, 0xff);
       enc_cbc[k] ^= random32 >> 3;
       if (++k >= sizeof(enc_cbc)) k = 0;
   }
+
+  // ******
+
+  rfm22_init_normal(saved_settings.min_frequency_Hz, saved_settings.max_frequency_Hz, rfm22_freqHopSize());
+
+  rfm22_TxDataByte_SetCallback(ph_TxDataByteCallback);
+  rfm22_RxDataByte_SetCallback(ph_RxDataByteCallback);
+
+  rfm22_setFreqCalibration(saved_settings.rf_xtal_cap);
+  ph_setNominalCarrierFrequency(saved_settings.frequency_Hz);
+  ph_setDatarate(saved_settings.max_rf_bandwidth);
+  ph_setTxPower(saved_settings.max_tx_power);
+
+  ph_set_remote_encryption(0, saved_settings.aes_enable, (const void *)saved_settings.aes_key);
+  ph_set_remote_serial_number(0, saved_settings.destination_id);
+
+  // ******
 }
 
 // *****************************************************************************
diff --git a/flight/PipXtreme/ppm.c b/flight/PipXtreme/ppm.c
index fbee8e258..42e51b855 100644
--- a/flight/PipXtreme/ppm.c
+++ b/flight/PipXtreme/ppm.c
@@ -40,6 +40,8 @@
 
 void ppm_1ms_tick(void)
 {
+	if (booting) return;
+
 	if (saved_settings.mode == MODE_PPM_TX)
 	{
 	}
@@ -49,11 +51,33 @@ void ppm_1ms_tick(void)
 	}
 }
 
+// *************************************************************
+// return a byte for the tx packet transmission.
+//
+// return value < 0 if no more bytes available, otherwise return byte to be sent
+
+int16_t ppm_TxDataByteCallback(void)
+{
+	return -1;
+}
+
+// *************************************************************
+// we are being given a received byte
+//
+// return TRUE to continue current packet receive, otherwise return FALSe to halt current packet reception
+
+bool ppm_RxDataByteCallback(uint8_t b)
+{
+	return true;
+}
+
 // *************************************************************
 // call this from the main loop (not interrupt) as often as possible
 
 void ppm_process(void)
 {
+	if (booting) return;
+
 	if (saved_settings.mode == MODE_PPM_TX)
 	{
 	}
@@ -65,12 +89,27 @@ void ppm_process(void)
 
 // *************************************************************
 
-void ppm_init(void)
+void ppm_init(uint32_t our_sn)
 {
 	#if defined(PPM_DEBUG)
 		DEBUG_PRINTF("\r\nPPM init\r\n");
 	#endif
 
+	if (saved_settings.mode == MODE_PPM_TX)
+		rfm22_init_tx_stream(saved_settings.min_frequency_Hz, saved_settings.max_frequency_Hz);
+	else
+	if (saved_settings.mode == MODE_PPM_RX)
+		rfm22_init_rx_stream(saved_settings.min_frequency_Hz, saved_settings.max_frequency_Hz);
+
+	rfm22_TxDataByte_SetCallback(ppm_TxDataByteCallback);
+	rfm22_RxDataByte_SetCallback(ppm_RxDataByteCallback);
+
+    rfm22_setFreqCalibration(saved_settings.rf_xtal_cap);
+	rfm22_setNominalCarrierFrequency(saved_settings.frequency_Hz);
+	rfm22_setDatarate(saved_settings.max_rf_bandwidth, FALSE);
+	rfm22_setTxPower(saved_settings.max_tx_power);
+
+	rfm22_setTxStream();			// TEST ONLY
 }
 
 // *************************************************************
diff --git a/flight/PipXtreme/rfm22b.c b/flight/PipXtreme/rfm22b.c
index 482081687..b04fdb57c 100644
--- a/flight/PipXtreme/rfm22b.c
+++ b/flight/PipXtreme/rfm22b.c
@@ -287,7 +287,8 @@ uint16_t			timeout_ms = 20000;					//
 uint16_t			timeout_sync_ms = 3;				//
 uint16_t			timeout_data_ms = 20;				//
 
-t_rfm22_TxDataCallback		tx_data_callback_function;
+t_rfm22_TxDataByteCallback		tx_data_byte_callback_function;
+t_rfm22_RxDataByteCallback		rx_data_byte_callback_function;
 
 // ************************************
 // SPI read/write
@@ -922,6 +923,10 @@ void rfm22_setTxMode(uint8_t mode)
 			// add some data
 			for (uint16_t j = wr - rd; j > 0; j--)
 			{
+//				int16_t b = -1;
+//				if (tx_data_byte_callback_function)
+//					b = tx_data_byte_callback_function();
+
 				rfm22_burstWrite(tx_data_addr[rd++]);
 				if (++i >= max_bytes) break;
 			}
@@ -1082,6 +1087,12 @@ void rfm22_processRxInt(void)
 			for (register uint16_t i = RX_FIFO_HI_WATERMARK; i > 0; i--)
 			{
 				register uint8_t b = rfm22_burstRead();	// read a byte from the rf modules RX FIFO buffer
+
+				if (rx_data_byte_callback_function)
+				{
+					rx_data_byte_callback_function(b);
+				}
+
 				if (wr < sizeof(rx_buffer))
 					rx_buffer[wr++] = b;				// save the byte into our rx buffer
 			}
@@ -1151,11 +1162,18 @@ void rfm22_processRxInt(void)
 			{	// their must still be data in the RX FIFO we need to get
 
 				rfm22_startBurstRead(RFM22_fifo_access);
-				while (wr < len)
-				{
-					if (wr >= sizeof(rx_buffer)) break;
-					rx_buffer[wr++] = rfm22_burstRead();
-				}
+					while (wr < len)
+					{
+						register uint8_t b = rfm22_burstRead();
+
+						if (rx_data_byte_callback_function)
+						{
+							rx_data_byte_callback_function(b);
+						}
+
+						if (wr >= sizeof(rx_buffer)) break;
+						rx_buffer[wr++] = b;
+					}
 				rfm22_endBurstRead();
 
 				rx_buffer_wr = wr;
@@ -1220,6 +1238,10 @@ uint8_t rfm22_topUpRFTxFIFO(void)
 		// add some data
 		for (uint16_t j = wr - rd; j > 0; j--)
 		{
+//			int16_t b = -1;
+//			if (tx_data_byte_callback_function)
+//				b = tx_data_byte_callback_function();
+
 			rfm22_burstWrite(tx_data_addr[rd++]);
 			if (++i >= max_bytes) break;
 		}
@@ -1794,9 +1816,8 @@ uint8_t rfm22_getFreqCalibration(void)
 
 void rfm22_1ms_tick(void)
 {	// call this once every ms
-
-	if (!initialized)
-		return;				// we haven't yet been initialized
+	if (booting) return;
+	if (!initialized) return;		// we haven't yet been initialized
 
 	if (rf_mode != RX_SCAN_SPECTRUM)
 	{
@@ -1809,8 +1830,8 @@ void rfm22_1ms_tick(void)
 
 void rfm22_process(void)
 {
-	if (!initialized)
-		return;				// we haven't yet been initialized
+	if (booting) return;
+	if (!initialized) return;	// we haven't yet been initialized
 
 	#if !defined(RFM22_EXT_INT_USE)
 		if (rf_mode != RX_SCAN_SPECTRUM)
@@ -1942,9 +1963,14 @@ void rfm22_process(void)
 
 // ************************************
 
-void rfm22_TxData_SetCallback(t_rfm22_TxDataCallback new_function)
+void rfm22_TxDataByte_SetCallback(t_rfm22_TxDataByteCallback new_function)
 {
-	tx_data_callback_function = new_function;
+	tx_data_byte_callback_function = new_function;
+}
+
+void rfm22_RxDataByte_SetCallback(t_rfm22_RxDataByteCallback new_function)
+{
+	rx_data_byte_callback_function = new_function;
 }
 
 // ************************************
@@ -2028,7 +2054,8 @@ int rfm22_resetModule(uint8_t mode, uint32_t min_frequency_hz, uint32_t max_freq
 	rssi = 0;
 	rssi_dBm = -200;
 
-	tx_data_callback_function = NULL;
+	tx_data_byte_callback_function = NULL;
+	rx_data_byte_callback_function = NULL;
 
 	rx_buffer_current = 0;
 	rx_buffer_wr = 0;
diff --git a/flight/PipXtreme/stream.c b/flight/PipXtreme/stream.c
index f354cdc61..512cec886 100644
--- a/flight/PipXtreme/stream.c
+++ b/flight/PipXtreme/stream.c
@@ -43,6 +43,8 @@
 
 void stream_1ms_tick(void)
 {
+	if (booting) return;
+
 	if (saved_settings.mode == MODE_STREAM_TX)
 	{
 	}
@@ -52,11 +54,33 @@ void stream_1ms_tick(void)
 	}
 }
 
+// *************************************************************
+// return a byte for the tx packet transmission.
+//
+// return value < 0 if no more bytes available, otherwise return byte to be sent
+
+int16_t stream_TxDataByteCallback(void)
+{
+	return -1;
+}
+
+// *************************************************************
+// we are being given a received byte
+//
+// return TRUE to continue current packet receive, otherwise return FALSe to halt current packet reception
+
+bool stream_RxDataByteCallback(uint8_t b)
+{
+	return true;
+}
+
 // *************************************************************
 // call this from the main loop (not interrupt) as often as possible
 
 void stream_process(void)
 {
+	if (booting) return;
+
 	if (saved_settings.mode == MODE_STREAM_TX)
 	{
 	}
@@ -68,12 +92,27 @@ void stream_process(void)
 
 // *************************************************************
 
-void stream_init(void)
+void stream_init(uint32_t our_sn)
 {
 	#if defined(STREAM_DEBUG)
 		DEBUG_PRINTF("\r\nSTREAM init\r\n");
 	#endif
 
+	if (saved_settings.mode == MODE_STREAM_TX)
+		rfm22_init_tx_stream(saved_settings.min_frequency_Hz, saved_settings.max_frequency_Hz);
+	else
+	if (saved_settings.mode == MODE_STREAM_RX)
+		rfm22_init_rx_stream(saved_settings.min_frequency_Hz, saved_settings.max_frequency_Hz);
+
+	rfm22_TxDataByte_SetCallback(stream_TxDataByteCallback);
+	rfm22_RxDataByte_SetCallback(stream_RxDataByteCallback);
+
+    rfm22_setFreqCalibration(saved_settings.rf_xtal_cap);
+	rfm22_setNominalCarrierFrequency(saved_settings.frequency_Hz);
+	rfm22_setDatarate(saved_settings.max_rf_bandwidth, FALSE);
+	rfm22_setTxPower(saved_settings.max_tx_power);
+
+	rfm22_setTxStream();			// TEST ONLY
 }
 
 // *************************************************************