ParaTNC is a software (hardware design coming) intended to work on STM32F100RB microcontroler and cheap STM32VLDISCOVERY
evaluation board as an multi function APRS controler. It supports key elements of what good APRS device should have:
-> Two directional KISS TNC (no init strings required).
-> WIDE1-1 digipeater, with an option to limit digipeating only to SSIDs 7, 8 and 9.
-> Weather station with support for various meteo sensors like: DS18B20 for temperature, MS5611 for pressure, LaCrosse TX20 for wind and DHT22 for humidity.
-> Extensive telemetry with an information about the count of receved, transmitted and digipeated frames plus status of weather sensors.
-> Support for VE.Direct serial protocol used in Victron PV charging controllers. The data about currents and voltages in the PV system are transmitted using APRS telemetry.
2. LICENSING
ParaTNC software and hardware are licensed under terms included to the source code in 'LICENSE' file
3. SUPPORTED FEATURES OD VE.Direct PROTOCOL
Most of Victron devices have a support both for binary and text serial protocol. By default the text procol (VE.Direct) is
always enabled and a device will send from its own telegrams each couple of seconds. The communication via VE.Direct is
avaliable through dedicated socket on the charging controller which is just 3.3V TTL levels UART, so no external ICs is
required to connect the PV controller to an evaluation board. In the MPPT series the comm socket is located on the bottom
side of the chargin controller below the fuse holder.
Exact pinout of the VE.Direct comm socket is as follows, assuming that terminal screws are facing down:
-> Ground
-> TX, data from host to the PV controller
-> RX, data from PV controller to the host
The controller sends a lot of different data which cannot be completely transmitted through APRS network due to radioprotocol
limitations. Only these parameters are transmitted:
-> Battery Current (charging as positive, discharging as negative) in third channel of telemetry.
-> Battery Voltage as fourth telemetry channel.
-> PV cell Voltage as fifth telemetry channel.
-> Charging Controller status (like current charging mode) and minimum/maximum battery current in last 10 minutes.
-> Error Codes if any (short circuit, overheat, overvoltage on PV or battery input)