MeshCom 4.0 uses the AX.25 protocol for the payload data as defined for APRS. (aprs101.pdf APRS PROTOCOL REFERENCE Version 1.0 2000, Page 12)
Find use:
- Identifier - APRS data type identifier
- Message ID - 32-bit LSB->MSB unique value
- MAX-HOP - max. 7 (mask 0x07) default 5 is used which allows 4 more passes.
- 0x80 - Identifier whether this message has already run via MQTT server.
- 0x40 - Identifier that this message is to be supplemented per MeshClient with the callsign of the forwarding station. For measurement and control purposes.
- Source address - This field contains the callsign and SSID of the transmitting station.
- Destination Address - This field may contain an APRS destination callsign or "*" for transmissions to ALL.
- Digipeater - There can be 0 to 8 digipeater call signs in this field. Note: These digipeater addresses can be overwritten by a generic APRS digipeater path (specified by the SSID of the destination address).
- Information - This field contains transport data. The first character of this field is the APRS data type identifier, which indicates what type of data follows.
- Frame Check Sequence - The FCS is a sequence of 16 bits used to check the integrity of a received frame.
Messages:
Text messages:
:|!MMMMMM|!HH|OE0XXX-99|>*|:|Text message|!00|!HW|!MOD|FCS#
Text messages with Path from Mesh:
:|!MMMMMM|!HH|OE0XXX-99,OE3XXX-12,OE3YY-12|>*|:|Text message|!00|!HW|!MOD|FCS#
Position messages:
!|!MMMMMM|!HH|OE0XXX-99|>*|!|4800.00|N|/|01600.00|E|#| BBB /A=HHHH|!00|!HW|!MOD|FCS#
Legend:
Protocol elements:
| ... is only used to show the separations here in the text
Message elements
Short code Field name Variable type : ! Message identifier Version 4.0 MMMMMM Message ID 32-bit LSB->MSB HH MAX-HOP 8-bit bit mask 0x07 Message via MQTT server Bit mask 0x80 Insert path in mesh (with comma as separator) Bit mask 0x40 4800.00 Latitude Degree/decimal x 100 01600.00 Longidude Degree/decimal x 100 N N ord / S outh char / APRS SYMBOL group (/ or \) char E E ast / W est char # APRS SYMBOL char BBB Battery status in % int 0 - 100 /A=HHH GPS sea level (m) int 0 - 40000 Message completion closes the APRS message area 0x00 HW Hardware ID (see extra table) unsigned int 16-bit MOD LoRa Modulation ID (MediumSlow...3) 32-bit LSB->MSB FCS# Checksum incl. identifier and 0x00 from message completion 8-bit (see table)
MeshCom hardware
Hardware ID HW Type MCU Type LoRa type HW abbreviation HW version 1 TTGO ESP32 Paxcounter ESP32 SX1278 TLORA V2 2 TTGO ESP32 Paxcounter ESP32 SX1278 TLORA V1 3 TTGO ESP32 Paxcounter ESP32 SX1278 TLORA V2 1.6 4 TTGO T-Beam ESP32 SX1278 T-BEAM 1.1 5 TTGO T-Beam ESP32 SX1262 T-BEAM 0.7 0.7 6 TTGO T-Beam ESP32 SX1268 T-BEAM 1268 1.1 1268 7 T-Echo LoRa SX1262 nRF SX1262 T-ECHO 9 Wisblock RAK4631 nRF Wisblock nRF RAK4631 10 WiFi LoRa 32 v3 nRF SX1262 HELTEC V3 11 WiFi LoRa 32 v2 nRF SX1276 HELTEC V2 12 Ebyte Lora E22 ESP32 SX1278 E22
MeshCom modulations
MOD ID Transmission range Planned range (km) Transmission speed Parameter 0 Extended range 10-20 fast 1 Extended range 10-20 slow (robust) 0.275 kbps 2 Additional extended range 20-40 slow (robust) 0.183 kbps 3 Normal range 5-10 slow (robust) 4 Normal range 5-10 fast 5.469 kbps 5 Local area 0-5 slow (robust) 6 Local area 0-5 fast 21.875 kbps
Message elements
| Short code | Field name | Variable type |
|---|---|---|
| : ! | Message identifier | Version 4.0 |
| MMMMMM | Message ID | 32-bit LSB->MSB |
| HH | MAX-HOP | 8-bit bit mask 0x07 |
| Message via MQTT server | Bit mask 0x80 | |
| Insert path in mesh (with comma as separator) | Bit mask 0x40 | |
| 4800.00 | Latitude | Degree/decimal x 100 |
| 01600.00 | Longidude | Degree/decimal x 100 |
| N | N ord / S outh | char |
| / | APRS SYMBOL group (/ or \) | char |
| E | E ast / W est | char |
| # | APRS SYMBOL | char |
| BBB | Battery status in % | int 0 - 100 |
| /A=HHH | GPS sea level (m) | int 0 - 40000 |
| Message completion | closes the APRS message area | 0x00 |
| HW | Hardware ID (see extra table) | unsigned int 16-bit |
| MOD | LoRa Modulation ID (MediumSlow...3) | 32-bit LSB->MSB |
| FCS# | Checksum incl. identifier and 0x00 from message completion | 8-bit (see table) |
MeshCom hardware
| Hardware ID | HW Type | MCU Type | LoRa type | HW abbreviation | HW version |
|---|---|---|---|---|---|
| 1 | TTGO ESP32 Paxcounter | ESP32 | SX1278 | TLORA | V2 |
| 2 | TTGO ESP32 Paxcounter | ESP32 | SX1278 | TLORA | V1 |
| 3 | TTGO ESP32 Paxcounter | ESP32 | SX1278 | TLORA | V2 1.6 |
| 4 | TTGO T-Beam | ESP32 | SX1278 | T-BEAM | 1.1 |
| 5 | TTGO T-Beam | ESP32 | SX1262 | T-BEAM 0.7 | 0.7 |
| 6 | TTGO T-Beam | ESP32 | SX1268 | T-BEAM 1268 | 1.1 1268 |
| 7 | T-Echo LoRa SX1262 | nRF | SX1262 | T-ECHO | |
| 9 | Wisblock RAK4631 | nRF | Wisblock nRF | RAK4631 | |
| 10 | WiFi LoRa 32 v3 | nRF | SX1262 | HELTEC | V3 |
| 11 | WiFi LoRa 32 v2 | nRF | SX1276 | HELTEC | V2 |
| 12 | Ebyte Lora E22 | ESP32 | SX1278 | E22 |
MeshCom modulations
| MOD ID | Transmission range | Planned range (km) | Transmission speed | Parameter |
|---|---|---|---|---|
| 0 | Extended range | 10-20 | fast | |
| 1 | Extended range | 10-20 | slow (robust) | 0.275 kbps |
| 2 | Additional extended range | 20-40 | slow (robust) | 0.183 kbps |
| 3 | Normal range | 5-10 | slow (robust) | |
| 4 | Normal range | 5-10 | fast | 5.469 kbps |
| 5 | Local area | 0-5 | slow (robust) | |
| 6 | Local area | 0-5 | fast | 21.875 kbps |