Add FHSS support

examples/SX127x/SX127x_Receive_FHSS/SX127x_Receive_FHSS.ino

@@ -0,0 +1,110 @@
+/*
+   RadioLib SX127x Transmit with Frequency Hopping Example
+
+   This example transmits packets using SX1278 LoRa radio module.
+   Each packet contains up to 256 bytes of data, in the form of:
+    - Arduino String
+    - null-terminated char array (C-string)
+    - arbitrary binary data (byte array)
+
+   Other modules from SX127x/RFM9x family can also be used.
+
+   For default module settings, see the wiki page
+   https://github.com/jgromes/RadioLib/wiki/Default-configuration#sx127xrfm9x---lora-modem
+
+   For full API reference, see the GitHub Pages
+   https://jgromes.github.io/RadioLib/
+
+   The SX1276 / 7 / 8 / 9 supports FHSS or Frequency Hopping Spread Spectrum.
+   Once a hopping period is set and a transmission is started the radio
+   will begin triggering interrupts every hop period where the radio frequency
+   is changed to the next channel.
+*/
+
+#include <RadioLib.h> //Click here to get the library: http://librarymanager/All#RadioLib
+
+// SX1276 has the following connections:
+const int pin_cs = 10;
+const int pin_dio0 = 2;
+const int pin_dio1 = 9;
+const int pin_rst = 3;
+SX1276 radio = new Module(pin_cs, pin_dio0, pin_rst, pin_dio1);
+
+volatile bool rxComplete = false;
+volatile bool fhssChange = false;
+
+// the channel frequencies can be generated randomly or hard coded
+float channels[] = {908.0, 906.0, 907.0, 905.0, 903.0, 910.0, 909.0};
+int numberOfChannels = sizeof(channels) / sizeof(float);
+
+int hopsCompleted = 0;
+
+void setup() {
+  Serial.begin(9600);
+
+  // begin radio on home channel
+  Serial.print(F("[SX127x] Initializing ... "));
+  int state = radio.begin(channels[0]);
+  if (state != RADIOLIB_ERR_NONE) {
+    Serial.print(F("Failed with code: "));
+    Serial.println(state);
+  }
+  else
+    Serial.println(F("Success!"));
+
+  // set hop period to enable FHSS
+  state = radio.setFHSSHoppingPeriod(9);
+  if (state != RADIOLIB_ERR_NONE) {
+    Serial.print(F("Error setting hopping period: "));
+    Serial.println(state);
+  }
+  radio.setDio0Action(dio0ISR); // called when transmission is finished
+  radio.setDio1Action(dio1ISR); // called after a transmission has started, so we can move to next freq
+
+  // start listening for LoRa packets
+  Serial.print(F("[SX1278] Starting to listen ... "));
+  state = radio.startReceive();
+  if (state != RADIOLIB_ERR_NONE) {
+    Serial.print(F("failed, code "));
+    Serial.println(state);
+    while (true);
+  }
+}
+
+void loop() {
+  if (rxComplete == true) {
+    uint8_t incomingBuffer[255];
+    radio.readData(incomingBuffer, 255);
+    uint8_t receivedBytes = radio.getPacketLength();
+    Serial.write(incomingBuffer, receivedBytes);
+    Serial.println();
+
+    Serial.print(F("Hops completed: "));
+    Serial.println(hopsCompleted);
+    hopsCompleted = 0;
+
+    radio.startReceive();
+
+    rxComplete = false;
+  }
+
+  if (fhssChange == true) {
+    radio.setFrequency(channels[radio.getFHSSChannel() % numberOfChannels]);
+
+    hopsCompleted++;
+    radio.clearFHSSInt();
+    fhssChange = false;
+  }
+}
+
+// ISR when DIO0 goes low
+// called when transmission is complete or when RX is received
+void dio0ISR(void) {
+  rxComplete = true;
+}
+
+// ISR when DIO1 goes low
+// called when FhssChangeChannel interrupt occurs (at the beginning of each transmission)
+void dio1ISR(void) {
+  fhssChange = true;
+}

examples/SX127x/SX127x_Transmit_FHSS/SX127x_Transmit_FHSS.ino

@@ -0,0 +1,113 @@
+/*
+   RadioLib SX127x Transmit with Frequency Hopping Example
+
+   This example transmits packets using SX1278 LoRa radio module.
+   Each packet contains up to 256 bytes of data, in the form of:
+    - Arduino String
+    - null-terminated char array (C-string)
+    - arbitrary binary data (byte array)
+
+   Other modules from SX127x/RFM9x family can also be used.
+
+   For default module settings, see the wiki page
+   https://github.com/jgromes/RadioLib/wiki/Default-configuration#sx127xrfm9x---lora-modem
+
+   For full API reference, see the GitHub Pages
+   https://jgromes.github.io/RadioLib/
+
+   The SX1276 / 7 / 8 / 9 supports FHSS or Frequency Hopping Spread Spectrum.
+   Once a hopping period is set and a transmission is started the radio
+   will begin triggering interrupts every hop period where the radio frequency
+   is changed to the next channel.
+*/
+
+#include <RadioLib.h> //Click here to get the library: http://librarymanager/All#RadioLib
+
+// SX1276 has the following connections:
+const int pin_cs = 10;
+const int pin_dio0 = 2;
+const int pin_dio1 = 9;
+const int pin_rst = 3;
+SX1276 radio = new Module(pin_cs, pin_dio0, pin_rst, pin_dio1);
+
+volatile bool xmitComplete = false;
+volatile bool fhssChange = false;
+
+// the channel frequencies can be generated randomly or hard coded
+float channels[] = {908.0, 906.0, 907.0, 905.0, 903.0, 910.0, 909.0};
+int numberOfChannels = sizeof(channels) / sizeof(float);
+
+int hopsCompleted = 0;
+int counter = 0;
+
+void setup() {
+  Serial.begin(9600);
+
+  // begin radio on home channel
+  Serial.print(F("[SX127x] Initializing ... "));
+  int state = radio.begin(channels[0]);
+  if (state != RADIOLIB_ERR_NONE) {
+    Serial.print(F("Failed with code: "));
+    Serial.println(state);
+  }
+  else
+    Serial.println(F("Success!"));
+
+  // set hop period to enable FHSS
+  state = radio.setFHSSHoppingPeriod(9);
+  if(state != RADIOLIB_ERR_NONE) {
+    Serial.print(F("Error setting hopping period: "));
+    Serial.println(state);
+  }
+
+  radio.setDio0Action(dio0ISR); // called when transmission is finished
+  radio.setDio1Action(dio1ISR); // called after a transmission has started, so we can move to next freq
+
+  Serial.print(F("Transmitting packet..."));
+
+  String longOutput = "Let's create a really long packet to trigger lots of hop interrupts. A packet can be up to 256 bytes long. This packet is 222 bytes so using sf = 9, bw = 125, timeOnAir is 1488ms. 1488ms / (9*4.10ms) = 40 hops. Counter: ";
+
+  state = radio.startTransmit(longOutput + counter);
+  if (state != RADIOLIB_ERR_NONE) {
+    Serial.print(F("Error transmitting with code: "));
+    Serial.println(state);
+  }
+}
+
+void loop() {
+  if (xmitComplete == true) {
+    xmitComplete = false;
+    Serial.println(F("Transmit complete"));
+    Serial.print(F("Radio after xmit is on channel: "));
+    Serial.println(radio.getFHSSChannel());
+    // the FHSS channel is automatically reset to 0 upon end of transmission
+
+    radio.setFrequency(channels[radio.getFHSSChannel() % numberOfChannels]); // Return to home channel before next transaction
+
+    Serial.print(F("Hops completed: "));
+    Serial.println(hopsCompleted);
+    hopsCompleted = 0;
+
+    radio.startReceive();
+  }
+
+  if (fhssChange == true) {
+    radio.setFrequency(channels[radio.getFHSSChannel() % numberOfChannels]);
+
+    hopsCompleted++;
+    fhssChange = false;
+    radio.clearFHSSInt();
+  }
+}
+
+// ISR when DIO0 goes low
+// called when transmission is complete or when RX is received
+void dio0ISR(void) {
+  xmitComplete = true;
+}
+
+// ISR when DIO1 goes low
+// called when FhssChangeChannel interrupt occurs (at regular HoppingPeriods)
+void dio1ISR(void) {
+  fhssChange = true;
+}

keywords.txt

@@ -142,6 +142,10 @@ setDirectAction	KEYWORD2
 readBit	KEYWORD2
 enableBitSync	KEYWORD2
 disableBitSync	KEYWORD2
+setFHSSHoppingPeriod	KEYWORD2
+getFHSSHoppingPeriod	KEYWORD2
+getFHSSChannel	KEYWORD2
+clearFHSSInt	KEYWORD2
 
 # RF69-specific
 setAESKey	KEYWORD2

src/modules/SX127x/SX127x.cpp

@@ -375,7 +375,12 @@ int16_t SX127x::startReceive(uint8_t len, uint8_t mode) {
   int16_t modem = getActiveModem();
   if(modem == RADIOLIB_SX127X_LORA) {
     // set DIO pin mapping
-    state = _mod->SPIsetRegValue(RADIOLIB_SX127X_REG_DIO_MAPPING_1, RADIOLIB_SX127X_DIO0_RX_DONE | RADIOLIB_SX127X_DIO1_RX_TIMEOUT, 7, 4);
+    if(_mod->SPIgetRegValue(RADIOLIB_SX127X_REG_HOP_PERIOD) > RADIOLIB_SX127X_HOP_PERIOD_OFF) {
+      state = _mod->SPIsetRegValue(RADIOLIB_SX127X_REG_DIO_MAPPING_1, RADIOLIB_SX127X_DIO0_RX_DONE | RADIOLIB_SX127X_DIO1_FHSS_CHANGE_CHANNEL, 7, 4);
+    }
+    else {
+      state = _mod->SPIsetRegValue(RADIOLIB_SX127X_REG_DIO_MAPPING_1, RADIOLIB_SX127X_DIO0_RX_DONE | RADIOLIB_SX127X_DIO1_RX_TIMEOUT, 7, 4);
+    }
 
     // set expected packet length for SF6
     if(_sf == 6) {
@@ -448,7 +453,12 @@ int16_t SX127x::startTransmit(uint8_t* data, size_t len, uint8_t addr) {
     }
 
     // set DIO mapping
-    _mod->SPIsetRegValue(RADIOLIB_SX127X_REG_DIO_MAPPING_1, RADIOLIB_SX127X_DIO0_TX_DONE, 7, 6);
+    if(_mod->SPIgetRegValue(RADIOLIB_SX127X_REG_HOP_PERIOD) > RADIOLIB_SX127X_HOP_PERIOD_OFF) {
+      _mod->SPIsetRegValue(RADIOLIB_SX127X_REG_DIO_MAPPING_1, RADIOLIB_SX127X_DIO0_TX_DONE | RADIOLIB_SX127X_DIO1_FHSS_CHANGE_CHANNEL, 7, 4);
+    }
+    else {
+      _mod->SPIsetRegValue(RADIOLIB_SX127X_REG_DIO_MAPPING_1, RADIOLIB_SX127X_DIO0_TX_DONE, 7, 6);
+    }
 
     // apply fixes to errata
     RADIOLIB_ERRATA_SX127X(false);
@@ -987,8 +997,12 @@ int16_t SX127x::setOOK(bool enableOOK) {
 }
 
 int16_t SX127x::setFrequencyRaw(float newFreq) {
-  // set mode to standby
-  int16_t state = setMode(RADIOLIB_SX127X_STANDBY);
+  int16_t state = RADIOLIB_ERR_NONE;
+
+  // set mode to standby if not FHSS
+  if(_mod->SPIgetRegValue(RADIOLIB_SX127X_REG_HOP_PERIOD) == RADIOLIB_SX127X_HOP_PERIOD_OFF) {
+    state = setMode(RADIOLIB_SX127X_STANDBY);
+  }
 
   // calculate register values
   uint32_t FRF = (newFreq * (uint32_t(1) << RADIOLIB_SX127X_DIV_EXPONENT)) / RADIOLIB_SX127X_CRYSTAL_FREQ;
@@ -1353,4 +1367,25 @@ void SX127x::readBit(RADIOLIB_PIN_TYPE pin) {
   updateDirectBuffer((uint8_t)digitalRead(pin));
 }
 
+int16_t SX127x::setFHSSHoppingPeriod(uint8_t freqHoppingPeriod) {
+  return(_mod->SPIsetRegValue(RADIOLIB_SX127X_REG_HOP_PERIOD, freqHoppingPeriod));
+}
+
+uint8_t SX127x::getFHSSHoppingPeriod(void) {
+  return(_mod->SPIgetRegValue(RADIOLIB_SX127X_REG_HOP_PERIOD)); 
+}
+
+uint8_t SX127x::getFHSSChannel(void) {
+  return(_mod->SPIgetRegValue(RADIOLIB_SX127X_REG_HOP_CHANNEL, 5, 0)); 
+}
+
+void SX127x::clearFHSSInt(void) {
+  int16_t modem = getActiveModem();
+  if(modem == RADIOLIB_SX127X_LORA) {
+    _mod->SPIwriteRegister(RADIOLIB_SX127X_REG_IRQ_FLAGS, getIRQFlags() | RADIOLIB_SX127X_CLEAR_IRQ_FLAG_FHSS_CHANGE_CHANNEL);
+  } else if(modem == RADIOLIB_SX127X_FSK_OOK) {
+    return; //These are not the interrupts you are looking for
+  }  
+}
+
 #endif

src/modules/SX127x/SX127x.h

@@ -1073,6 +1073,34 @@ class SX127x: public PhysicalLayer {
     */
     void readBit(RADIOLIB_PIN_TYPE pin);
 
+    /*!
+      \brief Sets the hopping period and enables FHSS
+
+      \param freqHoppingPeriod Integer multiple of symbol periods between hops
+
+      \returns \ref status_codes
+    */
+    int16_t setFHSSHoppingPeriod(uint8_t freqHoppingPeriod);
+
+        /*!
+      \brief Gets FHSS hopping period
+
+      \returns 8 bit period
+    */
+    uint8_t getFHSSHoppingPeriod(void);
+
+    /*!
+      \brief Gets the FHSS channel in use
+
+      \returns 6 bit channel number
+    */
+    uint8_t getFHSSChannel(void);
+
+    /*!
+      \brief Clear the FHSS interrupt
+    */
+    void clearFHSSInt(void);
+
 #if !defined(RADIOLIB_GODMODE) && !defined(RADIOLIB_LOW_LEVEL)
   protected:
 #endif