ParaTNC version DE06, January 5th 2020
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1. INTRODUCTION
ParaTNC is a hardware and a software which offers the functionality of multi function APRS controler. 
The software itself can also run on cheap STM32VLDISCOVERY board with slightly reduced functionality, but
with costs about 10..12 euro this gives the cheapest possible standalone APRS controller.
 
ParaAPRS 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.

ParaAPRS can be used as a standalone weather station controller w/o using the radio transmission. The sw
by default sends the measuremenets values 

2. ParaAPRS HARDWARE
The ParaTNC software can run on STM32VLDISCOVERY board but it really shows it full potential od it's own
dedicated hardware. This not only rub out all bodge wires required with prototype board. It gives 
few features which are hardly not possible without dedicated PCB
 a) Three different grounds separated one from the another
 	-> Controller
 	-> DB9 connector used to interface with a radio
 	-> Wind and temperature sensor
 b) Isolated DC-DC coverter to supply sensors with an option to connect another external power supply itself
 c) A relay used as a watchdog to reset wind & temperature sensor in case that no communication will be received.
 d) RS232 serial port avaliable on Cisco style RJ45 connector
 e) PCB designed to fit into Mikrotik RB411/RB711 enclosure.
 
ParaTNC PCB could be manufactured used a set of generber files locates in ./hardware/ directory a long with schematics and 
layout renders (top and bottom layer).
 
3. CURRENT OPEN POINTS AND ISSUES RELATED TO HW & SW
As usually every design has some flaws, less or more important. In case of ParaTNC they can be divided into two
parts, separately for software and hardware. Firstly in case of software an end user should USE ALWAYS THE SOURCE CODE
WITH THE NEWEST TAG marked as non-beta (like DE06). ParaTNC repository is used for daily development, so the last commit
can even sometimes don't compile at all, or consist some major bugs. 

Hardware workarounds for now are
-> Missing resistor in series with base of transistor T2. External 1k must be added in series with TX line
-> Foortprint location of R7 (RX_LVL) and R8 (TX_LVL) helipots are 'not optimal'. If 'normal' pots are to be used the vertical
   version must be chosen as flat one won't fit due to neighbouring components location. 
-> J1 power-in jack has reversed polarity (negative center)
-> The chineese manufacturer dropped the TX20 anemometer from the production which means that a supoprt to it
   became a little bit obsoloete for new installations. Support for Davis 6410 anemometer or any another with
   pulse output for windspeed and potentiometer (resistance output) for direction is ongoing and should be 
   avaliable in HW-Revision B and further SW releases.

4. LICENSING
ParaTNC software and hardware are licensed under terms included to the source code in 'LICENSE' file

5. 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)

6. TELEMETRY
If the VE.Direct protocol suppot is disabled the ParaTNC uses telemetry packets to send internal statistics and
general information about communication with sensors. Telemetry works in 10 minutes cycle, which means that packets are sent
every 10 minutes and they represents a state for the time between one and another. 

Analog channels:
1st Channel: Number of packets received in 10 minutes.
2nd Channel: Number of packets transmitted in 10 minutes (digi-ed + generated internally by the controller)
3rd Channel: Number of digipeated packets in 10 minutes.
4th Channel: Number of packet received from Host by KISS protocol
5th Channel: Optional temperature from Dalls One Wire sensor.

Digital Channels:
DS_QF_FULL	- Quality Factor for One Wire temperature sensor is FULL
DS_QF_DEGRAD	- Quality Factor for One Wire temperature sensor is DEGRADATED
DS_QF_NAVBLE	- Quality Factor for One Wire temperature sensor is NOT AVALIABLE
MS_QF_NAVBLE	- Quality Factor for MS5611 pressure sensor ins NOT AVALIABLE
DHT_QF_NAVBLE	- Quality Factor for DHT22 humidity & temperature is NOT AVALIABLE
TX20_SLEW	- LaCrosse TX20 anemometer driver dropped at least one measuremenet due to excesive slew rate.

Explantion of Quality Factors: Each measuremenets signal is kept along with the Quality Factor which represents the sensor condition
and value validity. If the QF is set to FULL it means that no communication problems happened between one telemetry cycle and another
DEGRADATED is set if at least once the communication problem happened (CRC calculation fail, timeout etc). NOT AVALIABLE is set
if all communication atempts failed and no valid measuremenet value is avaliable. By default each Quality Factor is set to 
NOT AVALIABLE after the telemetry packets are sent.  

The TX20 anemometer driver has a Slew Rate Limiter which keeps out all 'spikes' in values mostly due to RF interference. if the
difference between two consecutive measuremenets excedes hardcoded limit (9m/s) the software drops the value.

7. CONFIGURATION
At this point ParaTNC is delivered in form of source code which needs to be manually compiled by the user. Most options are 
configured by #define in './include/station_config.h' and then hard-coded by the C preprocessor during compilation. An example file
consist a lot of comments which explains what is what, but generally an user can choose there which mode should be enabled:
	-> KISS TNC
	-> KISS TNC + DIGI
	-> KISS TNC + DIGI + METEO
	-> VICTRON + DIGI + METEO
	-> VICTRON + DIGI

As You see there is no option to use a KISS modem and the VE.Direct protocol in the same time as the software support only
one UART in the micro. The KISS modem runs on default speed of 9600 bps. Telemetry is enabled by default and it will
trasmit channels values each 10 minutes and full channel descriptions each 70 minutes.

 
8. TOOLCHAIN AND COMPILATION
To build ParaTNC software 'GNU ARM Embedded Toolchain' is required. This set contains gcc-arm-none-eabi compiler,
gdb debugger, linker, HEX generator and set of libraries. ParaTNC is developed in Xubuntu 16.04LTS using 2016q-3
version. It shoud work fine in any newer version of the toolchain. The easies way to get everything installed
and configured is to use a packet manager, like aptitude in ubuntu/debian. 

Information about the toolchain, installation instructions etc can be found here:
https://launchpad.net/gcc-arm-embedded
https://developer.arm.com/open-source/gnu-toolchain/gnu-rm
https://launchpad.net/~team-gcc-arm-embedded/+archive/ubuntu/ppa

When everything is installed the reporistory can be cloned to local harddrive by using a command
 'git clone https://github.com/sp8ebc/ParaTNC'

The example config file is named 'station_config_example.h' and should be edited and then renamed to 
'station_config.h'. When everything is configured it is a time to go to 'Debug' directory and invoke
command 'make' there. The source should be automatically compiled and new hex file 'ParaTNC.hex'
should appear in the same directory. 

	Finished building target: ParaTNC.elf
 
	Invoking: Cross ARM GNU Create Flash Image
	arm-none-eabi-objcopy -O ihex "ParaTNC.elf"  "ParaTNC.hex"
	Finished building: ParaTNC.hex
 
	Invoking: Cross ARM GNU Print Size
	arm-none-eabi-size --format=berkeley "ParaTNC.elf"
	   text	   data	    bss	    dec	    hex	filename
	  50542	    576	   5544	  56662	   dd56	ParaTNC.elf
	Finished building: ParaTNC.siz
 

	22:29:38 Build Finished (took 13s.231ms)

7. LOADING THE HEX FILE INTO STM32VLDISCOVERY BOARD
The STM32VLDISCOVERY board has an ST-Link/V1 programmer-debugger on board which can be used to load a HEX file.
This ST-Link appears normally as a mass storage device which makes in unusable to be used by HEX loadin software
in Linux (as the device will be 'blocked' by the mass-storage driver). To workaround this problem, a configuration
of modprobe daemon should be changed to ignore the ST-Link and not load any driver for it.

This is done by invoking a command:
 'sudo echo "options usb-storage quirks=483:3744:i" >> /etc/modprobe.d/stlink_v1.conf'
What will create a new file called 'stlink_v1.conf' in modprobe directory. After the system reboot changes should
be applied and the programmer should be free to go. The kernel log should looks somehow like this below
	[90639.895886] usb 2-1.1: new full-speed USB device number 13 using ehci-pci
	[90639.990288] usb 2-1.1: New USB device found, idVendor=0483, idProduct=3744
	[90639.990294] usb 2-1.1: New USB device strings: Mfr=1, Product=2, SerialNumber=3
	[90639.990296] usb 2-1.1: Product: STM32 STLink
	[90639.990298] usb 2-1.1: Manufacturer: STMicroelectronics
	[90639.990300] usb 2-1.1: SerialNumber: Qÿr\xffffff86RV%X\xffffffc2\xffffff87
	[90639.990796] usb-storage 2-1.1:1.0: USB Mass Storage device detected
	[90639.992973] usb-storage 2-1.1:1.0: device ignored

The next step is to install texane-stlink which supports the ST-Link/V1 programmer and can be used to read an write
the flash memory. Installation is quite straight forward
  'git clone git://github.com/texane/stlink.git'
  'cd stlink.git'
  'make'
  'cd build/Relase'
  'sudo cp st-* /usr/bin'

At the end the HEX file can be loaded into the microcontroler by typing a command
  'sudo st-flash --format ihex write /dev/sr0 ParaTNC.hex' 
