Added crc header to LoRa frame.

CHANGELOG.md

@@ -0,0 +1,38 @@
+# Changelog
+
+All notable changes to this project will be documented in this file.
+
+    Added     : for new features.
+    Changed   : for changes in existing functionality.
+    Deprecated: for soon-to-be removed features.
+    Removed   : for now removed features.
+    Fixed     : for any bug fixes.
+    Security  : in case of vulnerabilities.
+
+## [0.0.1] - 2022-01-31
+
+### Added
+- Lora and TCP settings are now configurable via configuration file RPi-LoRa-KISS-TNC.ini
+
+### Changed
+- Better encoding of AX.25 frames: less/no crashes due to corrupted incomming frames
+
+### Deprecated
+- Configuration via config.py
+
+### Fixed
+- LoRa APRS header (<\xff\x01) was not added to the payload, due to an indentation fault. Long live Python!
+
+## [0.0.2] - 2022-02-08
+
+### Added
+- Support for 20dBm output power. Temporarily hard coded in source, but in next version it should be configurable via the configuration file.
+
+## [0.0.3] - 2022-02-10
+
+### Changed
+- 20dBm output power can now be selected from configuration file instead of being hard coded in program.
+- Enabled CRC in header of LoRa frames. Now frames are crc-checked at the receiving side.
+
+### Removed
+- Config.py as configuration is now completely removed. Configuration is now done completely via RPi-LoRa-KISS-TNC.ini

INSTALL.md

@@ -9,17 +9,72 @@ sudo apt install python3 python3-rpi.gpio python3-spidev aprx screen git python3
 
 Clone this repository.
 
-## Configuration
+## Configuration of APRX
 
-Edit /etc/aprx.conf according to example in aprx/aprx.conf.lora-aprs
+```
+In /etc/aprx.conf:
+
+    <interface>
+        tcp-device   127.0.0.1  10001    KISS
+        callsign     NOCALL-4  # callsign defaults to $mycall
+        tx-ok        true    # transmitter enable defaults to false
+    #   #telem-to-is  true # set to 'false' to disable
+    </interface>
+```
+
+## Start the LoRa KISS TNC
 
-## Start the LoRa KISS TNC and aprx server instance
 ```
 python3 Start_lora-tnc.py &
-sudo aprx
 ```
 
-## Stop the server's
+# Alternative method using the AX.25 stack
+
+This method is more complicated, but also more versitile as not all programs can communicate to a KISS device over TCP.
+
+## Install needed packages
+
 ```
-sudo killall aprx python3
+sudo apt install python3 python3-rpi.gpio python3-spidev aprx screen git python3-pil python3-smbus
 ```
+
+## Checkout the code
+
+Clone this repository.
+
+## Configuration of APRX
+
+```
+In /etc/aprx.conf
+
+    <interface>
+        ax25-device   $mycall
+        tx-ok        true  # transmitter enable defaults to false
+    #   #telem-to-is  true # set to 'false' to disable
+    </interface>
+```
+
+## Install and configure AX.25 stack
+
+```
+sudo apt install socat libax25 ax25-apps ax25-tools
+
+sudo nano /etc/ax25/axports
+
+add:
+   ax0     NOCALL-3        9600    255     2       430.775 MHz LoRa
+```
+
+## Start the LoRa KISS TNC
+
+```
+python3 Start_lora-tnc.py &
+```
+
+## Redirect KISS over TCP to AX.25 device
+
+```
+sudo socat PTY,raw,echo=0,link=/tmp/kisstnc TCP4:127.0.0.1:10001
+sudo kissattach /tmp/kisstnc ax0
+```
+

KissHelper.py

@@ -29,6 +29,7 @@
 # Changes by PE1RXF
 #
 # 2022-01-23: - in encode_address() added correct handling of has_been_repeated flag '*'
+# 2022-01-28: - in encode_kiss() and encode_address(): better exeption handling for corrupted or mal-formatted APRS frames
 #
 
 import struct
@@ -57,11 +58,22 @@ def encode_address(s, final):
         ssid = ssid[:-1]
         encoded_ssid |= 0b10000000
     
+    # If SSID was not pressent (and we added the default -0 to it), the has_been_repeated flag could be at the end of the call, so check that as well
+    # Also, there is a lot of bad software around (including this code) and ignorance of the specifications (are there any specs for LoRa APRS?), so always check for the has_been_repeated flag
+    if call[-1] == 42:
+        call = call[:-1]
+        encoded_ssid |= 0b10000000
+    
+    # SSID should now be one or two postions long and contain a number (idealy between 0 and 15).
+    if len(ssid) == 1 and ssid[0] > 47 and ssid[0] < 58:
         encoded_ssid |= (int(ssid) << 1) | 0b01100000 | (0b00000001 if final else 0)
+    elif len(ssid) == 2 and ssid[0] > 47 and ssid[0] < 58 and ssid[1] > 47 and ssid[1] < 58:
+        encoded_ssid |= (int(ssid) << 1) | 0b01100000 | (0b00000001 if final else 0)
+    else:
+        return None
     
     return encoded_call + [encoded_ssid]
 
-
 def decode_address(data, cursor):
     (a1, a2, a3, a4, a5, a6, a7) = struct.unpack("<BBBBBBB", data[cursor:cursor + 7])
     hrr = a7 >> 5
@@ -74,22 +86,56 @@ def decode_address(data, cursor):
         call = addr
     return (call, hrr, ext)
 
-
+########################################################################
+# Encode string from LoRa radio to AX.25 over KISS
+#
+# We must make no assumptions as the incomming frame could be carbage.
+# So make sure we think of everthing in order to prevent crashes.
+#
+# The original code from Thomas Kottek did a good job encoding propper APRS frames.
+# But when the frames where not what they should be, the program could crash.
+#
+########################################################################
 def encode_kiss(frame):
-    # Ugly frame disassembling
+
+    # First check: do we have a semi column (seperator path field and data field)
+    # Note that we could still be wrong: for example when the field seperator is corrupted and we now find a semi column from, lets say, an internet address in the data field...
     if not b":" in frame:
         return None
+    
+    # Split the frame in a path field and a data field
     path = frame.split(b":")[0]
+    data_field = frame[frame.find(b":") + 1:]
+
+    # The source address is always followed by a greather than sign, so lets see if its there.
+    # There is always a change that there is another greather than sign because the frame could be corrupted...
+    if not b">" in path:
+        return None
+
+    # Split the path into a source address and a digi-path array (because digis should be seperated by commas, but again, corruption....)
     src_addr = path.split(b">")[0]
     digis = path[path.find(b">") + 1:].split(b",")
+    
     # destination address
-    packet = encode_address(digis.pop(0).upper(), False)
+    return_value = encode_address(digis.pop(0).upper(), False)
+    if return_value is None:
+        return None
+    packet = return_value
+        
     # source address
-    packet += encode_address(path.split(b">")[0].upper(), len(digis) == 0)
+    return_value = encode_address(src_addr.upper(), len(digis) == 0)
+    if return_value is None:
+        return None
+    packet += return_value
+    
     # digipeaters
     for digi in digis:
         final_addr = digis.index(digi) == len(digis) - 1
-        packet += encode_address(digi.upper(), final_addr)
+        return_value = encode_address(digi.upper(), final_addr)
+        if return_value is None:
+            return None
+        packet += return_value  
+
     # control field
     packet += [0x03]  # This is an UI frame
     # protocol ID

LoraAprsKissTnc.py

@@ -38,12 +38,15 @@ class LoraAprsKissTnc(LoRa):
 
     # init has LoRa APRS default config settings - might be initialized different when creating object with parameters
     def __init__(self, queue, server, frequency=433.775, preamble=8, spreadingFactor=12, bandwidth=BW.BW125,
-                 codingrate=CODING_RATE.CR4_5, appendSignalReport = True, paSelect = 1, outputPower = 15, verbose=False):
+                 codingrate=CODING_RATE.CR4_5, appendSignalReport = True, paSelect = 1, MaxoutputPower = 15, outputPower = 15, verbose=False):
         # Init SX127x
         BOARD.setup()
 
         super(LoraAprsKissTnc, self).__init__(verbose)
         self.queue = queue
+        
+        if appendSignalReport == 'False':
+            appendSignalReport = False
         self.appendSignalReport = appendSignalReport
 
         self.set_mode(MODE.SLEEP)
@@ -51,12 +54,64 @@ class LoraAprsKissTnc(LoRa):
         self.set_freq(frequency)
         self.set_preamble(preamble)
         self.set_spreading_factor(spreadingFactor)
+        
+        if bandwidth == 'BW7_8':
+            bandwidth = BW.BW7_8
+        elif bandwidth == 'BW10_4':
+            bandwidth = BW.BW10_4            
+        elif bandwidth == 'BW15_6':
+            bandwidth = BW.BW15_6            
+        elif bandwidth == 'BW20_8':
+            bandwidth = BW.BW20_8            
+        elif bandwidth == 'BW31_25':
+            bandwidth = BW.BW31_25            
+        elif bandwidth == 'BW41_7':
+            bandwidth = BW.BW41_7            
+        elif bandwidth == 'BW62_5':
+            bandwidth = BW.BW62_5            
+        elif bandwidth == 'BW125':
+            bandwidth = BW.BW125            
+        elif bandwidth == 'BW250':
+            bandwidth = BW.BW250
+        elif bandwidth == 'BW500':
+            bandwidth = BW.BW500
+        else:
+            bandwidth = BW.BW125            
+            
         self.set_bw(bandwidth)
         self.set_low_data_rate_optim(True)
+        
+        if codingrate == 'CR4_5':
+            codingrate = CODING_RATE.CR4_5
+        elif codingrate == 'CR4_6':
+            codingrate = CODING_RATE.CR4_6
+        elif codingrate == 'CR4_7':
+            codingrate = CODING_RATE.CR4_7
+        elif codingrate == 'CR4_8':
+            codingrate = CODING_RATE.CR4_8
+        else:
+            codingrate = CODING_RATE.CR4_5
+        
         self.set_coding_rate(codingrate)        
+        
+        if outputPower == 20:
+            # Current limiter 180mA for +20dBm
+            self.set_ocp_trim(180)
+
+            # Set PA to +20dBm
+            self.set_pa_config(1, 15, 15)        
+            self.set_pa_dac(1)
+            #print("+20dBm")
+        else:
+            # Current limiter 100mA for 17dBm max
             self.set_ocp_trim(100)
             
-        self.set_pa_config(paSelect, outputPower)
+            self.set_pa_config(paSelect, MaxoutputPower, outputPower)                    
+            #print("max. +17dBm")            
+            
+        # CRC on
+        self.set_rx_crc(1)
+        
         self.set_max_payload_length(255)
         self.set_dio_mapping([0] * 6)
         self.server = server
@@ -77,6 +132,7 @@ class LoraAprsKissTnc(LoRa):
                             if self.aprs_data_type(data) == self.DATA_TYPE_THIRD_PARTY:
                                 # remove third party thing
                                 data = data[data.find(self.DATA_TYPE_THIRD_PARTY) + 1:]
+                            # Add LoRa-APRS header (original, this was indented one position further, only executed when above if-statement was true. Think it should be executed at all times.
                             data = self.LORA_APRS_HEADER + data
                             print("LoRa TX: " + repr(data))
                             self.transmit(data)

README.md

@@ -2,13 +2,13 @@
 
 This project was originally started by Tom Kottek (https://github.com/tomelec/RPi-LoRa-KISS-TNC). Because the program had some problems dealing with digipeated frames (it crashed when receiving a ssid with the 'has_been_digipeated' flag -*- set), I took on the task of fixing the code for my personal use.
 
-## Hardware
-
-I also designed my own (open source) hardware for it: a board holding a Raspberry Pi Zero 2 W, an SX1278 LoRa transceiver and a power supply with on/off button to safely switch on and off the system. The design files can be found on my website: [RPi LoRa_shield](https://meezenest.nl/mees/RPi_LoRa_shield.html)
-
 ## Software
 
 The software controls the LoRa transceiver connected to the Raspberry´s SPI bus and emulates a KISS TNC over TCP. That makes it possible to use existing software like APRX. It is also possible to attach the KISS interface to the AX.25 stack via socat/kissattach.
 
+## Hardware
+
+I also designed my own (open source) hardware for it: a board holding a Raspberry Pi Zero 2 W, an SX1278 LoRa transceiver and a power supply with on/off button to safely switch on and off the system. The design files can be found on my website: [RPi LoRa_shield](https://meezenest.nl/mees/RPi_LoRa_shield.html)
+
 ### To Do
-* A lot
+* Add raw TCP KISS socket for true AX.25 over KISS

RPi-LoRa-KISS-TNC.ini

@@ -0,0 +1,45 @@
+[LoRaSettings]
+# Settings for LoRa module
+frequency=433.775
+preamble=8
+spreadingFactor=12
+# Bandwidth:
+#    BW7_8
+#    BW10_4
+#    BW15_6
+#    BW20_8
+#    BW31_25
+#    BW41_7
+#    BW62_5
+#    BW125
+#    BW250
+#    BW500
+bandwidth=BW125
+# Coding Rate:
+#    CR4_5
+#    CR4_6
+#    CR4_7
+#    CR4_8
+codingrate=CR4_5
+appendSignalReport=False
+# paSelect only tested at 1
+paSelect=1
+# MaxoutputPower only tested at 15
+MaxoutputPower = 15
+# 0 ... 15 => +2 ... +17dBm
+# 20 = +20dBm
+outputPower = 20
+
+[KISS]
+# Settings for KISS
+TCP_HOST=0.0.0.0
+TCP_PORT_AX25=10001
+TCP_PORT_RAW =10002
+
+[AXUDP]
+# settings for AXUDP
+AXUDP_REMOTE_IP=192.168.0.185
+AXUDP_REMOTE_PORT=20000
+AXUDP_LOCAL_IP=0.0.0.0
+AXUDP_LOCAL_PORT=20000
+USE_AXUDP=False

Start_lora-tnc.py

@@ -21,6 +21,25 @@ from TCPServer import KissServer
 from AXUDPServer import AXUDPServer
 import config
 from LoraAprsKissTnc import LoraAprsKissTnc
+import configparser
+
+# Read configuration file #
+parser = configparser.ConfigParser()
+parser.read('/home/marcel/ham/RPi-LoRa-KISS-TNC/RPi-LoRa-KISS-TNC.ini')
+
+config_frequency = float(parser.get('LoRaSettings', 'frequency'))
+config_preamble = int(parser.get('LoRaSettings', 'preamble'))
+config_spreadingFactor = int(parser.get('LoRaSettings', 'spreadingFactor'))
+config_bandwidth = parser.get('LoRaSettings', 'bandwidth')
+config_codingrate = parser.get('LoRaSettings', 'codingrate')
+config_appendSignalReport = parser.get('LoRaSettings', 'appendSignalReport')
+config_paSelect = int(parser.get('LoRaSettings', 'paSelect'))
+config_MaxoutputPower = int(parser.get('LoRaSettings', 'MaxoutputPower'))
+config_outputPower = int(parser.get('LoRaSettings', 'outputPower'))
+
+config_TCP_HOST = parser.get('KISS', 'TCP_HOST')
+config_TCP_PORT_AX25 = int(parser.get('KISS', 'TCP_PORT_AX25'))
+config_TCP_PORT_RAW = int(parser.get('KISS', 'TCP_PORT_RAW'))
 
 # TX KISS frames go here (Digipeater -> TNC)
 kissQueue = Queue()
@@ -29,13 +48,14 @@ kissQueue = Queue()
 if config.USE_AXUDP:
   server = AXUDPServer(kissQueue, config.AXUDP_LOCAL_IP, config.AXUDP_LOCAL_PORT, config.AXUDP_REMOTE_IP, config.AXUDP_REMOTE_PORT)  
 else:
-  server = KissServer(kissQueue, config.TCP_HOST, config.TCP_PORT)
+  server = KissServer(kissQueue, config_TCP_HOST, config_TCP_PORT_AX25)
 
 server.setDaemon(True)
 server.start()
 
 # LoRa transceiver instance
-lora = LoraAprsKissTnc(kissQueue, server, verbose=False, appendSignalReport = config.APPEND_SIGNAL_REPORT)
+lora = LoraAprsKissTnc(kissQueue, server, frequency=config_frequency, preamble=config_preamble, spreadingFactor=config_spreadingFactor, bandwidth=config_bandwidth,
+                 codingrate=config_codingrate, appendSignalReport=config_appendSignalReport, paSelect = config_paSelect, MaxoutputPower = config_MaxoutputPower, outputPower = config_outputPower,verbose=True)
 
 # this call loops forever inside
 lora.startListening()

TCPServer.py

@@ -60,7 +60,7 @@ class KissServer(Thread):
             encoded_data = KissHelper.encode_kiss(data)
         except Exception as e:
             print("KISS encoding went wrong (exception while parsing)")
-            # traceback.print_tb(e.__traceback__)
+            traceback.print_tb(e.__traceback__)
             encoded_data = None
 
         if encoded_data != None:

pySX127x/SX127x/board_config.py

@@ -37,7 +37,8 @@ class BOARD:
     DIO1 = 23   # RaspPi GPIO 23
     DIO2 = 24   # RaspPi GPIO 24
     DIO3 = 25   # RaspPi GPIO 25
-    LED  = 18   # RaspPi GPIO 18 connects to the LED on the proto shield
+    LED  = 13   # RaspPi GPIO 18 connects to the LED on the proto shield
+		# Made it GPIO 13, as pin 18 is in use by Direwolf (M. Konstapel 2022-01-27)
     SWITCH = 4  # RaspPi GPIO 4 connects to a switch
 
     # The spi object is kept here

start_all.sh

@@ -0,0 +1,7 @@
+#!/bin/bash
+
+/usr/bin/python3 /home/marcel/ham/RPi-LoRa-KISS-TNC/Start_lora-tnc.py &
+sleep 10
+sudo /usr/bin/socat PTY,raw,echo=0,link=/tmp/lorakisstnc TCP4:127.0.0.1:10001 &
+sleep 3
+sudo /usr/sbin/kissattach /tmp/lorakisstnc ax2 &