[RTTY] Added AFSK support

examples/RTTY/RTTY_Transmit_AFSK/RTTY_Transmit_AFSK.ino

@@ -0,0 +1,133 @@
+/*
+   RadioLib RTTY Transmit AFSK Example
+
+   This example sends RTTY message using SX1278's
+   FSK modem. The data is modulated as AFSK.
+
+   Other modules that can be used for RTTY:
+    - SX127x/RFM9x
+    - RF69
+    - SX1231
+    - CC1101
+    - Si443x/RFM2x
+
+   For full API reference, see the GitHub Pages
+   https://jgromes.github.io/RadioLib/
+*/
+
+// include the library
+#include <RadioLib.h>
+
+// SX1278 has the following connections:
+// NSS pin:   10
+// DIO0 pin:  2
+// RESET pin: 9
+// DIO1 pin:  3
+SX1278 fsk = new Module(10, 2, 9, 3);
+
+// or using RadioShield
+// https://github.com/jgromes/RadioShield
+//SX1278 fsk = RadioShield.ModuleA;
+
+// create AFSK client instance using the FSK module
+// pin 5 is connected to SX1278 DIO2
+AFSKClient audio(&fsk, 5);
+
+// create RTTY client instance using the AFSK instance
+RTTYClient rtty(&audio);
+
+void setup() {
+  Serial.begin(9600);
+
+  // initialize SX1278
+  Serial.print(F("[SX1278] Initializing ... "));
+  // carrier frequency:           434.0 MHz
+  // bit rate:                    48.0 kbps
+  // frequency deviation:         50.0 kHz
+  // Rx bandwidth:                125.0 kHz
+  // output power:                13 dBm
+  // current limit:               100 mA
+  int state = fsk.beginFSK();
+
+  // when using one of the non-LoRa modules for RTTY
+  // (RF69, CC1101, Si4432 etc.), use the basic begin() method
+  // int state = fsk.begin();
+
+  if(state == ERR_NONE) {
+    Serial.println(F("success!"));
+  } else {
+    Serial.print(F("failed, code "));
+    Serial.println(state);
+    while(true);
+  }
+
+  // initialize RTTY client
+  // NOTE: Unlike FSK RTTY, AFSK requires no rounding of
+  //       the frequency shift.
+  Serial.print(F("[RTTY] Initializing ... "));
+  // space frequency:             400 Hz
+  // frequency shift:             170 Hz
+  // baud rate:                   45 baud
+  // encoding:                    ASCII (7-bit)
+  // stop bits:                   1
+  state = rtty.begin(400, 170, 45);
+  if(state == ERR_NONE) {
+    Serial.println(F("success!"));
+  } else {
+    Serial.print(F("failed, code "));
+    Serial.println(state);
+    while(true);
+  }
+
+  /*
+    // RadioLib also provides ITA2 ("Baudot") support
+    rtty.begin(400, 170, 45, ITA2);
+
+    // All transmissions in loop() (strings and numbers)
+    // will now be encoded using ITA2 code
+
+    // ASCII characters that do not have ITA2 equivalent
+    // will be sent as NUL (including lower case letters!)
+  */
+}
+
+void loop() {
+  Serial.print(F("[RTTY] Sending RTTY data ... "));
+
+  // send out idle condition for 500 ms
+  rtty.idle();
+  delay(500);
+
+  // RTTYClient supports all methods of the Serial class
+
+  // Arduino String class
+  String aStr = "Arduino String";
+  rtty.println(aStr);
+
+  // character array (C-String)
+  rtty.println("C-String");
+
+  // string saved in flash
+  rtty.println(F("Flash String"));
+
+  // character
+  rtty.println('c');
+
+  // byte
+  // formatting DEC/HEX/OCT/BIN is supported for
+  // any integer type (byte/int/long)
+  rtty.println(255, HEX);
+
+  // integer number
+  int i = 1000;
+  rtty.println(i);
+
+  // floating point number
+  float f = -3.1415;
+  rtty.println(f, 3);
+
+  Serial.println(F("done!"));
+
+  // wait for a second before transmitting again
+  delay(1000);
+}

src/protocols/RTTY/RTTY.cpp

@@ -106,12 +106,20 @@ uint16_t ITA2String::getBits(char c) {
 
 RTTYClient::RTTYClient(PhysicalLayer* phy) {
   _phy = phy;
+  _audio = nullptr;
+}
+
+RTTYClient::RTTYClient(AFSKClient* audio) {
+  _phy = audio->_phy;
+  _audio = audio;
 }
 
 int16_t RTTYClient::begin(float base, uint32_t shift, uint16_t rate, uint8_t encoding, uint8_t stopBits) {
   // save configuration
   _encoding = encoding;
   _stopBits = stopBits;
+  _baseHz = base;
+  _shiftHz = shift;
 
   switch(encoding) {
     case ASCII:
@@ -148,15 +156,17 @@ int16_t RTTYClient::begin(float base, uint32_t shift, uint16_t rate, uint8_t enc
   // calculate 24-bit frequency
   _base = (base * 1000000.0) / _phy->getFreqStep();
 
-  // set module frequency deviation to 0
-  int16_t state = _phy->setFrequencyDeviation(0);
+  // set module frequency deviation to 0 if using FSK
+  int16_t state = ERR_NONE;
+  if(_audio == nullptr) {
+    state = _phy->setFrequencyDeviation(0);
+  }
 
   return(state);
 }
 
 void RTTYClient::idle() {
-  _phy->transmitDirect();
-
+  transmitDirect();
   mark();
 }
 
@@ -190,7 +200,7 @@ size_t RTTYClient::write(uint8_t b) {
     mark();
   }
 
-  _phy->standby();
+  standby();
 
   return(1);
 }
@@ -391,7 +401,7 @@ size_t RTTYClient::println(double d, int digits) {
 
 void RTTYClient::mark() {
   uint32_t start = micros();
-  _phy->transmitDirect(_base + _shift);
+  transmitDirect(_base + _shift, _baseHz + _shiftHz);
   while(micros() - start < _bitDuration) {
     yield();
   }
@@ -399,7 +409,7 @@ void RTTYClient::mark() {
 
 void RTTYClient::space() {
   uint32_t start = micros();
-  _phy->transmitDirect(_base);
+  transmitDirect(_base, _baseHz);
   while(micros() - start < _bitDuration) {
     yield();
   }
@@ -505,3 +515,19 @@ size_t RTTYClient::printFloat(double number, uint8_t digits)  {
 
   return n;
 }
+
+int16_t RTTYClient::transmitDirect(uint32_t freq, uint32_t freqHz) {
+  if(_audio != nullptr) {
+    return(_audio->tone(freqHz));
+  } else {
+    return(_phy->transmitDirect(freq));
+  }
+}
+
+int16_t RTTYClient::standby() {
+  if(_audio != nullptr) {
+    return(_audio->noTone());
+  } else {
+    return(_phy->standby());
+  }
+}

src/protocols/RTTY/RTTY.h

@@ -3,6 +3,7 @@
 
 #include "../../TypeDef.h"
 #include "../PhysicalLayer/PhysicalLayer.h"
+#include "../AFSK/AFSK.h"
 
 #define ITA2_FIGS                                     0x1B
 #define ITA2_LTRS                                     0x1F
@@ -84,18 +85,25 @@ class ITA2String {
 class RTTYClient {
   public:
     /*!
-      \brief Default constructor.
+      \brief Constructor for 2-FSK mode.
 
       \param phy Pointer to the wireless module providing PhysicalLayer communication.
     */
     RTTYClient(PhysicalLayer* phy);
 
+    /*!
+      \brief Constructor for AFSK mode.
+
+      \param audio Pointer to the AFSK instance providing audio.
+    */
+    RTTYClient(AFSKClient* audio);
+
     // basic methods
 
     /*!
       \brief Initialization method.
 
-      \param base Base (space) RF frequency to be used in MHz.
+      \param base Base (space) frequency to be used in MHz (in 2-FSK mode), or the space tone frequency in Hz (in AFSK mode)
 
       \param shift Frequency shift between mark and space in Hz.
 
@@ -147,10 +155,11 @@ class RTTYClient {
   private:
 #endif
     PhysicalLayer* _phy;
+    AFSKClient* _audio;
 
     uint8_t _encoding;
-    uint32_t _base;
-    uint32_t _shift;
+    uint32_t _base, _baseHz;
+    uint32_t _shift, _shiftHz;
     uint32_t _bitDuration;
     uint8_t _dataBits;
     uint8_t _stopBits;
@@ -160,6 +169,9 @@ class RTTYClient {
 
     size_t printNumber(unsigned long, uint8_t);
     size_t printFloat(double, uint8_t);
+
+    int16_t transmitDirect(uint32_t freq = 0, uint32_t freqHz = 0);
+    int16_t standby();
 };
 
 #endif