Encode TNC2 monitor frame to KISS format

lib/KISS_TO_TNC2/KISS_TO_TNC2.cpp

@@ -0,0 +1,100 @@
+#include "KISS_TO_TNC2.h"
+
+bool validateTNC2Frame(const String &tnc2FormattedFrame);
+
+String encode_address_kiss(String tnc2Address, bool isLast);
+
+/*
+ * https://ham.zmailer.org/oh2mqk/aprx/PROTOCOLS
+
+	After successfull login, communication carries "TNC2" format
+	APRS messages.  Namely text encoding of AX.25 UI frames in
+	what became known as "TNC2 monitor style":
+
+	    SOURCE>DESTIN:payload
+	    SOURCE>DESTIN,VIA,VIA:payload
+
+	The SOURCE, DESTIN, and VIA fields are AX.25 address fields,
+        and have "-SSID" value annexed if the SSID is not zero.
+	Also in VIA-fields, if the "HAS BEEN DIGIPEATED" bit is set
+	(AX.25 v2 protocol feature) a star ('*') character is appended.
+        VIA-fields are separated by comma (',') from DESTIN, and each
+        other.
+
+	A double-colon (':') separates address data from payload.
+	The payload is passed _AS_IS_ without altering any message
+	content bytes, however ending at first CR or LF character
+	encountered in the packet.
+
+ */
+
+String encode_kiss(const String& tnc2FormattedFrame) {
+    String ax25Frame = "";
+
+    if (validateTNC2Frame(tnc2FormattedFrame)){
+        String address = "";
+        for (int p=0;p<tnc2FormattedFrame.indexOf(':');p++){
+            char currentChar = tnc2FormattedFrame.charAt(p);
+            if (currentChar == ':' || currentChar == '>' || currentChar == ','){
+                if (currentChar == '>'){
+                    // ax25 frame DST SRC
+                    // tnc2 frame SRC DST
+                    ax25Frame = encode_address_kiss(address, currentChar == ':') + ax25Frame;
+                } else {
+                    ax25Frame += encode_address_kiss(address, currentChar == ':');
+                }
+            } else {
+                address += currentChar;
+            }
+        }
+        ax25Frame += (char)APRS_CONTROL_FIELD;
+        ax25Frame += (char)APRS_INFORMATION_FIELD;
+        ax25Frame += tnc2FormattedFrame.substring(tnc2FormattedFrame.indexOf(':')+1);
+    }
+
+    String kissFrame = "";
+    kissFrame += (char)FEND; // start of frame
+    kissFrame += (char)CMD_DATA; // TNC0, DATA
+    for (int i = 0; i < ax25Frame.length(); ++i) {
+        char currentChar = tnc2FormattedFrame.charAt(i);
+        if (currentChar == (char)FEND) {
+            kissFrame += FESC;
+            kissFrame += TFEND;
+        } else if (currentChar == (char)FESC){
+            kissFrame += FESC;
+            kissFrame += TFESC;
+        } else {
+            kissFrame += currentChar;
+        }
+    }
+    kissFrame += (char)FEND; // end of frame
+    return kissFrame;
+}
+
+/**
+ * Encode adress in TNC2 monitor format to ax.25/kiss format
+ * @param tnc2Address
+ * @param isLast
+ * @return
+ */
+String encode_address_kiss(String tnc2Address, bool isLast) {
+    if (tnc2Address.indexOf('-') == -1){
+        tnc2Address += "-0";
+    }
+    bool hasBeenDigipited = tnc2Address.indexOf('*') != -1;
+
+    int ssid = tnc2Address.substring(tnc2Address.indexOf('-')+1).toInt();
+    // TODO: SSID should not be > 16
+    String kissAddress = "";
+    for (int i = 0; i < 6; ++i) {
+        if (tnc2Address.length() > i){
+            kissAddress += (char)(tnc2Address.charAt(i) << 1);
+        } else {
+            kissAddress += ' ';
+        }
+    }
+    kissAddress += (char)((ssid << 1) | 0b01100000 | (isLast ? 1 : 0) | (hasBeenDigipited ? 0b10000000 : 0));
+    return kissAddress;
+}
+
+bool validateTNC2Frame(const String &tnc2FormattedFrame) { return (tnc2FormattedFrame.indexOf(':') != -1) && (tnc2FormattedFrame.indexOf('>') != -1); }

lib/KISS_TO_TNC2/KISS_TO_TNC2.h

@@ -0,0 +1,9 @@
+#include <Arduino.h>
+#include "KISS.h"
+
+#define APRS_CONTROL_FIELD 0x03
+#define APRS_INFORMATION_FIELD 0xf0
+
+String encode_kiss(const String& tnc2FormattedFrame);
+
+String decode_kiss(String kissFormattedFrame);

src/TTGO_T-Beam_LoRa_APRS.ino

@@ -21,7 +21,7 @@
 #include <Adafruit_SPITFT_Macros.h>
 #include <gfxfont.h>
 #include <axp20x.h>
-#include "KISS.h"
+#include <KISS_TO_TNC2.h>
 
 // I2C LINES
 #define I2C_SDA 21
@@ -283,23 +283,6 @@ void writedisplaytext(String HeaderTxt, String Line1, String Line2, String Line3
   display.display();
   smartDelay(warten);
 }
-
-void encode_address(){
-
-}
-
-void decode_address(){
-
-}
-
-void encode_kiss(){
-
-}
-
-void decode_kiss(){
-
-}
-
 // + SETUP --------------------------------------------------------------+//
 
 void setup(){
@@ -405,7 +388,7 @@ void loop() {
           Serial.println(InputString);
         #endif
         #ifdef KISS_PROTOCOLL
-          //encode_kiss(InputString);
+          Serial.println(encode_kiss(InputString));
         #endif
         writedisplaytext("  ((RX))","",InputString,"","","",SHOW_RX_TIME);
       }

src/TTGO_T-Beam_LoRa_APRS_config.h

@@ -5,8 +5,8 @@
 // licensed under CC BY-NC-SA
 
 // USER DATA - USE THESE LINES TO MODIFY YOUR PREFERENCES
-//#define KISS_PROTOCOLL                                  // If enabled send and receive data in SIMPLE KISS format
-#define TEXT_PROTOCOLL                                // TEXT outpu data
+#define KISS_PROTOCOLL                                  // If enabled send and receive data in SIMPLE KISS format
+//#define TEXT_PROTOCOLL                                // TEXT outpu data
 #define CALLSIGN "SQ9MDD-11"                            // enter your callsign here - less then 6 letter callsigns please add "spaces" so total length is 6 (without SSID)
 //#define LONGITUDE_PRESET "02055.59E"                    // please in APRS notation DDDMM.mmE or DDDMM.mmW
 //#define LATIDUDE_PRESET "5215.02N"                      // please in APRS notation DDMM.mmN or DDMM.mmS