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swiftnav-multi

This repository includes Python and C code for reading multiple messages from Swift-Nav Piksi Multi. All the codes are tested in Linux environments and instructions are for Linux only.

The provided codes can perform the following tasks:

  • read multiple messages from the Piksi Multi (C/Python)
  • read and write settings through command line (without the console) (Python)

Setting-up Multi

For debugging purposes, Multi can be configured to work in simulation mode so that you do not have to go outside with a GPS antenna for testing your codes.

With Multi connected to your computer and Swift Console running:

  • Click the Settings tab
  • In the Simulator section, you will see a value for enabled. Click on this.
  • Set the value of enabled to True by selecting True from the drop-down menu right part of the tab.
  • Then click Save to Flash button.

The official documentation can be found here.

Modifying the code

This code only processes few messages like LLH position, velocity, baseline solution, and UTC. Please refer the SPB Manual for additional messages. For finding the elements in a message, check relevant h file in /c/include/libsbp of sbp library. For example, SBP_MSG_POS_LLH is in navigation.h.

Python Code

SBP library has issues with working with Python 3 as of writing of this code. So it is necessary to use Python 2. Below instructions assume that conda has already been installed.

Environment setup

Install required libraries

pip install sbp

Running the Code

Simply run the py file (default port = \dev\ttyUSB0, default baud rate = 115200). For issues, see troubleshooting.

python2 read_sbp.py

For different ports or baud rates:

python read_sbp.py -p /path/to/port -b baud_rate

Changing the Settings without the Console

  1. To rest:
python2 reset_multi.py -p /path/to/port -b baud_rate
  1. To write settings to Multi from an ini file
python2 write_from_ini_file.py -f /path/to/ini/file

There are few ini files saved in settings_files directory. These files are first saved through the SwiftNav Console. Usually those files are tied to serial number of the GPS. So you need different files for different GPS units. 3. Running the code through bash files There are few bash files added so that you do not need to manually type all the arguments.

sudo chmod +x name/of/the/bashfile
./name/of/the/bashfile

C-Code

Dependencies

Multi sends messages using a custom protocol called Swaiftnav Binary Protocol (SBP). Running this C-code needs the installation of few dependencies.

  • sbp-lib : for parsing the SBP messages
  • lib-serial : for communicating with Multi through the serial port

SBP Library - sbp-lib

  1. Clone the official sbp library 
    git clone https://github.com/swift-nav/libsbp.git
  2. Install dependencies 
    sudo apt-get -y install build-essential pkg-config cmake doxygen check
  3. Create a build directory 
    cd libsbp/c
mkdir build
cd build
  4. Build and install 
    cmake ../
make
sudo make install

Serial Port Library - lib-serial

  1. Clone the repo 
    git clone git://sigrok.org/libserialport
  2. Install required packages 
    sudo apt-get -y install autoconf
sudo apt-get -y install libtool
  3. Build the library 
    cd libserialport
./autogen.sh
./configure
make
sudo make install

On 64-bit Systems

On 64-bit systems, you might need to install below packages.

sudo apt-get -y install libgtk2.0-0:i386 libidn11:i386 libglu1-mesa:i386
sudo apt-get -y install libpangox-1.0-0:i386 libpangoxft-1.0-0:i386

Running the code

  1. Compiling

    mkdir build
cd build
cmake ../
make

  2. Running (see Troubleshooting below for issues)

    ./read_rtk -p /dev/ttyUSB0

Troubleshooting

  1. Error: "libserialport.so.0: cannot open shared object" - solution: configure dynamic linker run-time bindings 
    sudo ldconfig /usr/local/lib
  2. Cannot open the serial port (replace /path/to/ports with your actual port, eg: sudo chmod 777 /dev/ttyUSB0) 
    sudo chmod 777 /path/to/port
  3. Error: AttributeError: 'module' object has no attribute 'Struct' - solution python SBP libraries need specific versions of "construct" and "requests-futures" libraries. 
    sudo pip install construct==2.9.33
sudo pip install requests-futures==0.9.5