diff --git a/RFM69.cpp b/RFM69.cpp
index 259d9cd..154a537 100644
--- a/RFM69.cpp
+++ b/RFM69.cpp
@@ -41,7 +41,7 @@ uint8_t RFM69::ACK_RECEIVED; // should be polled immediately after sending a pac
 int16_t RFM69::RSSI;          // most accurate RSSI during reception (closest to the reception)
 volatile bool RFM69::_haveData;
 
-RFM69::RFM69(uint8_t slaveSelectPin, uint8_t interruptPin, bool isRFM69HW)
+RFM69::RFM69(uint8_t slaveSelectPin, uint8_t interruptPin, bool isRFM69HW, SPIClass *spi)
 {
   _slaveSelectPin = slaveSelectPin;
   _interruptPin = interruptPin;
@@ -49,6 +49,7 @@ RFM69::RFM69(uint8_t slaveSelectPin, uint8_t interruptPin, bool isRFM69HW)
   _spyMode = false;
   _powerLevel = 31;
   _isRFM69HW = isRFM69HW;
+  _spi = spi;
 #if defined(RF69_LISTENMODE_ENABLE)
   _isHighSpeed = true;
   _haveEncryptKey = false;
@@ -111,13 +112,16 @@ bool RFM69::initialize(uint8_t freqBand, uint16_t nodeID, uint8_t networkID)
 
   digitalWrite(_slaveSelectPin, HIGH);
   pinMode(_slaveSelectPin, OUTPUT);
+  if(_spi == nullptr){
+    _spi = &SPI;
+  }
 #if defined(ESP32)
-    SPI.begin(18,19,23,5); //SPI3  (SCK,MISO,MOSI,CS)
-    //SPI.begin(14,12,13,15); //SPI2   (SCK,MISO,MOSI,CS) 
+  _spi->begin(18,19,23,5); //SPI3  (SCK,MISO,MOSI,CS)
+  //_spi->begin(14,12,13,15); //SPI2  (SCK,MISO,MOSI,CS) 
 #else
-    SPI.begin();
-#endif
-  
+  _spi->begin();
+#endif  
+
 #ifdef SPI_HAS_TRANSACTION
   _settings = SPISettings(8000000, MSBFIRST, SPI_MODE0);
 #endif
@@ -325,14 +329,14 @@ void RFM69::sendFrame(uint16_t toAddress, const void* buffer, uint8_t bufferSize
 
   // write to FIFO
   select();
-  SPI.transfer(REG_FIFO | 0x80);
-  SPI.transfer(bufferSize + 3);
-  SPI.transfer((uint8_t)toAddress);
-  SPI.transfer((uint8_t)_address);
-  SPI.transfer(CTLbyte);
+  _spi->transfer(REG_FIFO | 0x80);
+  _spi->transfer(bufferSize + 3);
+  _spi->transfer((uint8_t)toAddress);
+  _spi->transfer((uint8_t)_address);
+  _spi->transfer(CTLbyte);
 
   for (uint8_t i = 0; i < bufferSize; i++)
-    SPI.transfer(((uint8_t*) buffer)[i]);
+    _spi->transfer(((uint8_t*) buffer)[i]);
   unselect();
 
   // no need to wait for transmit mode to be ready since its handled by the radio
@@ -349,12 +353,12 @@ void RFM69::interruptHandler() {
   {
     setMode(RF69_MODE_STANDBY);
     select();
-    SPI.transfer(REG_FIFO & 0x7F);
-    PAYLOADLEN = SPI.transfer(0);
+    _spi->transfer(REG_FIFO & 0x7F);
+    PAYLOADLEN = _spi->transfer(0);
     PAYLOADLEN = PAYLOADLEN > 66 ? 66 : PAYLOADLEN; // precaution
-    TARGETID = SPI.transfer(0);
-    SENDERID = SPI.transfer(0);
-    uint8_t CTLbyte = SPI.transfer(0);
+    TARGETID = _spi->transfer(0);
+    SENDERID = _spi->transfer(0);
+    uint8_t CTLbyte = _spi->transfer(0);
     TARGETID |= (uint16_t(CTLbyte) & 0x0C) << 6; //10 bit address (most significant 2 bits stored in bits(2,3) of CTL byte
     SENDERID |= (uint16_t(CTLbyte) & 0x03) << 8; //10 bit address (most sifnigicant 2 bits stored in bits(0,1) of CTL byte
 
@@ -372,7 +376,7 @@ void RFM69::interruptHandler() {
     ACK_REQUESTED = CTLbyte & RFM69_CTL_REQACK; // extract ACK-requested flag
     interruptHook(CTLbyte);     // TWS: hook to derived class interrupt function
 
-    for (uint8_t i = 0; i < DATALEN; i++) DATA[i] = SPI.transfer(0);
+    for (uint8_t i = 0; i < DATALEN; i++) DATA[i] = _spi->transfer(0);
 
     DATA[DATALEN] = 0; // add null at end of string // add null at end of string
     unselect();
@@ -435,9 +439,9 @@ void RFM69::encrypt(const char* key) {
     memcpy(_encryptKey, key, 16);
 #endif
     select();
-    SPI.transfer(REG_AESKEY1 | 0x80);
+    _spi->transfer(REG_AESKEY1 | 0x80);
     for (uint8_t i = 0; i < 16; i++)
-      SPI.transfer(key[i]);
+      _spi->transfer(key[i]);
     unselect();
   }
   writeReg(REG_PACKETCONFIG2, (readReg(REG_PACKETCONFIG2) & 0xFE) | (key ? 1 : 0));
@@ -460,8 +464,8 @@ int16_t RFM69::readRSSI(bool forceTrigger) {
 uint8_t RFM69::readReg(uint8_t addr)
 {
   select();
-  SPI.transfer(addr & 0x7F);
-  uint8_t regval = SPI.transfer(0);
+  _spi->transfer(addr & 0x7F);
+  uint8_t regval = _spi->transfer(0);
   unselect();
   return regval;
 }
@@ -469,8 +473,8 @@ uint8_t RFM69::readReg(uint8_t addr)
 void RFM69::writeReg(uint8_t addr, uint8_t value)
 {
   select();
-  SPI.transfer(addr | 0x80);
-  SPI.transfer(value);
+  _spi->transfer(addr | 0x80);
+  _spi->transfer(value);
   unselect();
 }
 
@@ -483,15 +487,15 @@ void RFM69::select() {
 #endif
 
 #ifdef SPI_HAS_TRANSACTION
-  SPI.beginTransaction(_settings);
+  _spi->beginTransaction(_settings);
 #else
   // set RFM69 SPI settings explicitly
-  SPI.setDataMode(SPI_MODE0);
-  SPI.setBitOrder(MSBFIRST);
+  _spi->setDataMode(SPI_MODE0);
+  _spi->setBitOrder(MSBFIRST);
   #ifdef defined(__SAMD51__)
-    SPI.setClockDivider(SPI_CLOCK_DIV16);
+    _spi->setClockDivider(SPI_CLOCK_DIV16);
   #else
-    SPI.setClockDivider(SPI_CLOCK_DIV2);
+    _spi->setClockDivider(SPI_CLOCK_DIV2);
   #endif
 #endif
   digitalWrite(_slaveSelectPin, LOW);
@@ -501,7 +505,7 @@ void RFM69::select() {
 void RFM69::unselect() {
   digitalWrite(_slaveSelectPin, HIGH);
 #ifdef SPI_HAS_TRANSACTION
-  SPI.endTransaction();
+  _spi->endTransaction();
 #endif  
   // restore SPI settings to what they were before talking to RFM69
 #if defined (SPCR) && defined (SPSR)
@@ -573,8 +577,8 @@ void RFM69::readAllRegs()
   for (uint8_t regAddr = 1; regAddr <= 0x4F; regAddr++)
   {
     select();
-    SPI.transfer(regAddr & 0x7F); // send address + r/w bit
-    regVal = SPI.transfer(0);
+    _spi->transfer(regAddr & 0x7F); // send address + r/w bit
+    regVal = _spi->transfer(0);
     unselect();
 
     Serial.print(regAddr, HEX);
@@ -1053,10 +1057,10 @@ void RFM69::listenModeInterruptHandler(void)
 
   burstRemaining.l = 0;
 
-  SPI.transfer(REG_FIFO & 0x7F);
-  PAYLOADLEN = SPI.transfer(0);
+  _spi->transfer(REG_FIFO & 0x7F);
+  PAYLOADLEN = _spi->transfer(0);
   PAYLOADLEN = PAYLOADLEN > 64 ? 64 : PAYLOADLEN; // precaution
-  TARGETID = SPI.transfer(0);
+  TARGETID = _spi->transfer(0);
   if(!(_spyMode || TARGETID == _address || TARGETID == RF69_BROADCAST_ADDR) // match this node's address, or broadcast address or anything in spy mode
      || PAYLOADLEN < 3) // address situation could receive packets that are malformed and don't fit this library's extra fields
   {
@@ -1066,13 +1070,13 @@ void RFM69::listenModeInterruptHandler(void)
 
   // We've read the target, and will read the sender id and two time offset bytes for a total of 4 bytes
   DATALEN = PAYLOADLEN - 4;
-  SENDERID = SPI.transfer(0);
-  burstRemaining.b[0] =  SPI.transfer(0);  // and get the time remaining
-  burstRemaining.b[1] =  SPI.transfer(0);
+  SENDERID = spi->transfer(0);
+  burstRemaining.b[0] =  _spi->transfer(0);  // and get the time remaining
+  burstRemaining.b[1] =  _spi->transfer(0);
   RF69_LISTEN_BURST_REMAINING_MS = burstRemaining.l;
 
   for (uint8_t i = 0; i < DATALEN; i++)
-    DATA[i] = SPI.transfer(0);
+    DATA[i] = _spi->transfer(0);
 
   if (DATALEN < RF69_MAX_DATA_LEN)
     DATA[DATALEN] = 0; // add null at end of string
@@ -1179,17 +1183,17 @@ void RFM69::listenModeSendBurst( uint8_t targetNode, const void* buffer, uint8_t
     noInterrupts();
     // write to FIFO
     select();
-    SPI.transfer(REG_FIFO | 0x80);
-    SPI.transfer(size + 4);      // two bytes for target and sender node, two bytes for the burst time remaining
-    SPI.transfer(targetNode);
-    SPI.transfer(_address);
+    _spi->transfer(REG_FIFO | 0x80);
+    _spi->transfer(size + 4);      // two bytes for target and sender node, two bytes for the burst time remaining
+    _spi->transfer(targetNode);
+    _spi->transfer(_address);
 
     // We send the burst time remaining with the packet so the receiver knows how long to wait before trying to reply
-    SPI.transfer(timeRemaining.b[0]);
-    SPI.transfer(timeRemaining.b[1]);
+    _spi->transfer(timeRemaining.b[0]);
+    _spi->transfer(timeRemaining.b[1]);
 
     for (uint8_t i = 0; i < size; i++) {
-      SPI.transfer(((uint8_t*) buffer)[i]);
+      _spi->transfer(((uint8_t*) buffer)[i]);
     }
 
     unselect();
@@ -1202,4 +1206,4 @@ void RFM69::listenModeSendBurst( uint8_t targetNode, const void* buffer, uint8_t
   setMode(RF69_MODE_STANDBY);
   reinitRadio();
 }
-#endif
\ No newline at end of file
+#endif