Lora aprs text packets compatible mode

Author: sh123

codec2talkie/build.gradle

@@ -10,8 +10,8 @@ android {
         applicationId "com.radio.codec2talkie"
         minSdkVersion 23
         targetSdkVersion 30
-        versionCode 152
-        versionName "1.52"
+        versionCode 153
+        versionName "1.53"
 
         testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
     }

codec2talkie/src/main/java/com/radio/codec2talkie/MainActivity.java

@@ -491,12 +491,18 @@ private void updateStatusText(ProtocolFactory.ProtocolType protocolType) {
                 status += getString(R.string.voax25_label);
             }
 
+            // Lora aprs text packets
+            boolean textPacketsEnabled = SettingsWrapper.isTextPacketsEnabled(_sharedPreferences);
+            if (textPacketsEnabled) {
+                status += getString(R.string.text_packets_label);
+            }
             // Digirepeater
             boolean isDigirepeaterEnabled = _sharedPreferences.getBoolean(PreferenceKeys.AX25_DIGIREPEATER_ENABLED, false);
             if (isDigirepeaterEnabled) {
                 status += getString(R.string.digirepeater_label);
             }
 
+            // APRSIS
             boolean aprsisEnabled = SettingsWrapper.isAprsIsEnabled(_sharedPreferences);
             if (aprsisEnabled) {
                 status += getString(R.string.aprsis_label);

codec2talkie/src/main/java/com/radio/codec2talkie/protocol/Ax25.java

@@ -15,6 +15,8 @@
 import com.radio.codec2talkie.transport.Transport;
 
 import java.io.IOException;
+import java.nio.ByteBuffer;
+import java.nio.charset.StandardCharsets;
 
 public class Ax25 implements Protocol {
 
@@ -26,6 +28,7 @@ public class Ax25 implements Protocol {
     private String _digipath;
     private boolean _isVoax25Enabled;
     private boolean _isDigiRepeaterEnabled;
+    private boolean _useTextPackets;
 
     private ProtocolCallback _parentProtocolCallback;
 
@@ -44,6 +47,7 @@ public void initialize(Transport transport, Context context, ProtocolCallback pr
         // NOTE, may need to pass through sendData/sendAudio
         _digipath = sharedPreferences.getString(PreferenceKeys.AX25_DIGIPATH, "").toUpperCase();
         _isVoax25Enabled = SettingsWrapper.isVoax25Enabled(sharedPreferences);
+        _useTextPackets = SettingsWrapper.isTextPacketsEnabled(sharedPreferences);
         _isDigiRepeaterEnabled = sharedPreferences.getBoolean(PreferenceKeys.AX25_DIGIREPEATER_ENABLED, false);
     }
 
@@ -93,7 +97,7 @@ public void sendData(String src, String dst, String path, byte[] dataPacket) thr
         ax25Packet.digipath = path == null ? _digipath : path;
         ax25Packet.isAudio = false;
         ax25Packet.rawData = dataPacket;
-        byte[] ax25Frame = ax25Packet.toBinary();
+        byte[] ax25Frame = _useTextPackets ? ax25Packet.toTextBinary() : ax25Packet.toBinary();
         if (ax25Frame == null) {
             Log.e(TAG, "Cannot convert AX.25 data packet to binary");
             _parentProtocolCallback.onProtocolTxError();

codec2talkie/src/main/java/com/radio/codec2talkie/protocol/ax25/AX25Packet.java

@@ -2,11 +2,14 @@
 
 import androidx.annotation.NonNull;
 
+import com.radio.codec2talkie.protocol.aprs.tools.AprsIsData;
 import com.radio.codec2talkie.tools.DebugTools;
 import com.radio.codec2talkie.tools.TextTools;
 
 import java.nio.BufferUnderflowException;
 import java.nio.ByteBuffer;
+import java.nio.charset.StandardCharsets;
+import java.util.Arrays;
 
 public class AX25Packet {
 
@@ -28,6 +31,21 @@ public class AX25Packet {
     public void fromBinary(byte[] data) {
         isValid = false;
         if (data == null) return;
+        // lora text packet with 0x3c,0xff,0x01 prefix
+        if (data.length > 3 && data[0] == (byte)0x3c && data[1] == (byte)0xff && data[2] == (byte)0x01) {
+            String rawText = new String(Arrays.copyOfRange(data, 3, data.length), StandardCharsets.US_ASCII);
+            AprsIsData textPacket = AprsIsData.fromString(rawText);
+            if (textPacket != null) {
+                src = textPacket.src;
+                dst = textPacket.dst;
+                digipath = textPacket.rawDigipath;
+                rawData = textPacket.data.getBytes(StandardCharsets.US_ASCII);
+                isAudio = false;
+                isValid = true;
+                return;
+            }
+        }
+        // binary packet
         ByteBuffer buffer = ByteBuffer.wrap(data);
         try {
             // dst
@@ -81,6 +99,18 @@ public void fromBinary(byte[] data) {
         }
     }
 
+    public byte[] toTextBinary() {
+        byte[] packetContent = toString().getBytes(StandardCharsets.US_ASCII);
+        // lora aprs prefix 0x3c,0xff,0x01
+        ByteBuffer textPacketBuffer = ByteBuffer.allocateDirect(packetContent.length + 3);
+        textPacketBuffer.put((byte)0x3c).put((byte)0xff).put((byte)0x01);
+        textPacketBuffer.put(packetContent);
+        textPacketBuffer.flip();
+        byte[] ax25Frame = new byte[textPacketBuffer.remaining()];
+        textPacketBuffer.get(ax25Frame);
+        return ax25Frame;
+    }
+
     public byte[] toBinary() {
         ByteBuffer buffer = ByteBuffer.allocate(MaximumSize);
         String[] rptCallsigns = new String[] {};

codec2talkie/src/main/java/com/radio/codec2talkie/settings/PreferenceKeys.java

@@ -67,6 +67,7 @@ public final class PreferenceKeys {
     public static String APP_AUDIO_DESTINATION = "app_audio_destination";
 
     public static String AX25_VOAX25_ENABLE = "aprs_voax25_enable";
+    public static String AX25_TEXT_PACKETS_ENABLE = "aprs_text_packets_enable";
     public static String AX25_CALLSIGN = "aprs_callsign";
     public static String AX25_SSID = "aprs_ssid";
     public static String AX25_DIGIPATH = "aprs_digipath";

codec2talkie/src/main/java/com/radio/codec2talkie/settings/SettingsWrapper.java

@@ -93,6 +93,10 @@ public static boolean isVoax25Enabled(SharedPreferences sharedPreferences) {
                 !isFreeDvSoundModemModulation(sharedPreferences);   // no voax25 in freedv
     }
 
+    public static boolean isTextPacketsEnabled(SharedPreferences sharedPreferences) {
+        return sharedPreferences.getBoolean(PreferenceKeys.AX25_TEXT_PACKETS_ENABLE, false);
+    }
+
     public static boolean isAprsIsEnabled(SharedPreferences sharedPreferences) {
         return sharedPreferences.getBoolean(PreferenceKeys.APRS_IS_ENABLE, false);
     }

codec2talkie/src/main/res/values/strings.xml

@@ -232,6 +232,7 @@
     <string name="menu_send_position">Send position</string>
 
     <string name="voax25_label">&#9742;</string>
+    <string name="text_packets_label">&#128276;</string>
 
     <string name="menu_aprs_log">View log</string>
 
@@ -366,4 +367,6 @@
     <string name="map_menu_rotate_map">Rotate map with compass</string>
     <string name="map_menu_show_range">Show range circles</string>
     <string name="map_menu_show_moving">Show moving stations</string>
+    <string name="aprs_text_packets_enable_title">Enable text packets</string>
+    <string name="aprs_text_packets_enable_summary">Send lora aprs compatible text packets (0x3c,0xff,0x01 prefix)</string>
 </resources>

codec2talkie/src/main/res/xml/preferences.xml

@@ -215,6 +215,14 @@
             app:defaultValue="true">
         </SwitchPreference>
 
+        <SwitchPreference
+            app:key="aprs_text_packets_enable"
+            app:title="@string/aprs_text_packets_enable_title"
+            app:summary="@string/aprs_text_packets_enable_summary"
+            app:dependency="aprs_enable"
+            app:defaultValue="false">
+        </SwitchPreference>
+
         <EditTextPreference
             app:key="aprs_callsign"
             app:title="@string/aprs_callsign_title"