diff --git a/src/modules/SX127x.cpp b/src/modules/SX127x.cpp
index d4eb23b3..4dc03c31 100644
--- a/src/modules/SX127x.cpp
+++ b/src/modules/SX127x.cpp
@@ -421,9 +421,9 @@ int16_t SX127x::directMode(uint32_t FRF) {
   
   // user requested to start transmitting immediately (required for RTTY)
   if(FRF != 0) {
-    _mod->SPIsetRegValue(SX127X_REG_FRF_MSB, (FRF & 0xFF0000) >> 16);
-    _mod->SPIsetRegValue(SX127X_REG_FRF_MID, (FRF & 0x00FF00) >> 8);
-    _mod->SPIsetRegValue(SX127X_REG_FRF_LSB, FRF & 0x0000FF);
+    _mod->SPIwriteRegister(SX127X_REG_FRF_MSB, (FRF & 0xFF0000) >> 16);
+    _mod->SPIwriteRegister(SX127X_REG_FRF_MID, (FRF & 0x00FF00) >> 8);
+    _mod->SPIwriteRegister(SX127X_REG_FRF_LSB, FRF & 0x0000FF);
   
     return(setMode(SX127X_TX));
   }
@@ -902,7 +902,7 @@ int16_t SX127x::setSyncWord(uint8_t* syncWord, size_t len) {
   }
 
   // check constraints
-  if(len > 7) {
+  if(len >= 7) {
     return(ERR_INVALID_SYNC_WORD);
   }
   
diff --git a/src/modules/SX127x.h b/src/modules/SX127x.h
index c8b33d41..622da902 100644
--- a/src/modules/SX127x.h
+++ b/src/modules/SX127x.h
@@ -4,6 +4,8 @@
 #include "TypeDef.h"
 #include "Module.h"
 
+#include "../protocols/PhysicalLayer.h"
+
 // SX127x series common LoRa registers
 #define SX127X_REG_FIFO                               0x00
 #define SX127X_REG_OP_MODE                            0x01
@@ -515,7 +517,7 @@
 #define SX127X_PLL_BANDWIDTH_225_KHZ                  0b10000000  //  7     6                    225 kHz
 #define SX127X_PLL_BANDWIDTH_300_KHZ                  0b11000000  //  7     6                    300 kHz (default)
 
-class SX127x {
+class SX127x: public PhysicalLayer {
   public:
     // constructor
     SX127x(Module* mod);
diff --git a/src/protocols/PhysicalLayer.h b/src/protocols/PhysicalLayer.h
new file mode 100644
index 00000000..975a926d
--- /dev/null
+++ b/src/protocols/PhysicalLayer.h
@@ -0,0 +1,22 @@
+#ifndef _KITELIB_PHYSICAL_LAYER_H
+#define _KITELIB_PHYSICAL_LAYER_H
+
+#include "TypeDef.h"
+
+class PhysicalLayer {
+  public:
+    // constructor
+    // this class is purely virtual and does not require explicit constructor
+    
+    // basic methods
+    virtual int16_t directMode(uint32_t FRF = 0) = 0;
+    virtual int16_t transmit(const char* data, uint8_t addr = 0) = 0;
+    virtual int16_t transmit(uint8_t* data, size_t len, uint8_t addr = 0) = 0;
+    virtual int16_t receive(uint8_t* data, size_t len) = 0;
+    
+    // configuration methods
+    virtual int16_t setFrequencyDeviation(float freqDev) = 0;
+
+};
+
+#endif