TechVisionCoproc

Vision coprocessor

Prerequisites

• g++
• cmake 2.8 and higher
• Optionnally, opencv and video4linux
• The comm library zmq is in the subdir zmq. Default builds for RaspberryPi, Odroid and roboRio2016 are supplied. For other platforms, you will have to build libzmq yourself (and get the c++ binding)

Installation

Move to the working directory. Copy the appropriate libzmq.a library located in zmq/lib/* to zmq/lib, e.g.:

  $ cp zmq/lib/odroid/libzmq.a zmq/lib

Then, the following series of commands will build the server and a test tool.

  $ mkdir build
  $ cd build
  $ cmake ..
  $ make

If everything went well, two binaries should be created:

• the coprocessor server: VisionCoproc
• a test utility: testcoproc

Execution

Launching VisionCoproc from the shell, we should get (modulo opencv camera warnings):

$ ./VisionCoproc
  T4K Vision Coprocessor v2016
  ----------------------

  * Using OpenCV v2.4.8
  * Using ZMQ v4.2

  Connecting with camera: Ok
  Hit Ctrl-C to quit
  Listening

If you open another shell and cd to the build directory, you can use the test tool to verify that communication is ok:

  $ ./testcoproc status
  T4K Vision Coprocessor Test Tool
  --------------------------------

  * using ZMQ v4.2

  Command processor status:
  Version 2016
  Image dump location: /media/data/images
   No job running
  Camera manager: 
   * camera 1 connected

Communication

Commands handled by the coprocessor so far:

• reset : stops processing, destroys results
• status : returns internal status
• saveimg : captures an image from camera and dumps it to disk
  
• test : executes a fake command
• r_test : sends back "Output of dummy_command: result = 42"
• r_saveimg : sends back filename of saved image from cam or "Trying to save empty image!" if no camera is connected.

Additional notes

• Sending a command always initiates a response. Typical use: roboRio sends "test", waits a bit and sends "r_test" to get the result.
• More than one command can be processed at the same time, but they have to be different.
• If a command such as "test" is sent twice in a row, the first response is "Started" (which is ok) but the second one is "Busy".
• If a command such as "test" is sent but the next command "r_test" is sent too early (before the end of the detection), the response is "Still thinking".
• Following a bad command, the response is "Unknown command".
• Following a reset, the response is "Done".

Adding commands

Adding new commands should be fairly easy: use the the test command associated to the object DummyCommand as a template and look for "INSERT_HERE" comments in the files CommandProcessor.*.