Control Daemon

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1 Overview

>>>>TODO Overview text.

Currently, booting up the camera is as follows:

  • A systemd service is activated which runs a shell script.
  • This script then loads a bitstream into the FPGA and uses other scripts and C programs to train LVDS channels and set up the HDMI output

When the service is disabled, the user can run this script manually, which:

  • Does not keep the user from running if it has already been activated by systemd.
  • And on the other hand, simple scripts which query the registers (e.g. to get the temperature of the sensor) can be activated even if the FPGA bitstream didn't load.

All of those lead to a solid lockup of the Beta, because if you write to one of those memory addresses which are used for communicating with the PL, and there is no handler in the FPGA, the ARM cores lock up solid, no recovery possible they basically wait for an ACK/NACK forever.

Research is taking place in the Labs here.

2 Structure

TODO: Add image which shows structure of module communication (WebGUI -> RESTServer > Daemon, and back)

The control daemon project currently consists of three different modules:

  • Web UI - HTML5, sends REST requests to the backend, currently by using JQuery (still evaluating alternatives).
  • RESTServer - receives REST requests, converts them to Flatbuffers packages and sends them to the daemon, through socket.
  • WSServer - receives WebSocket requests, converts them to Flatbuffers packages and sends them to the daemon, through socket.
  • Daemon - processes received packages and calls suitable handler.

TODO: Add JSON/REST package description from Lab (

3 Build

Required packages (names are varying between Linux distributions):

  • cmake
  • libsystemd-dev
  • libssl-dev


  • Install required packages
  • Clone beta-software repo
  • cd into cloned repo
  • cd software/control_daemon
  • mkdir build
  • cd build
  • cmake ..
  • make -j4

4 Setup daemon

5 Setup WebUI


To set/get parameters from command line, DaemonCLI can be used:

Syntax: DaemonCLI <module> set_/get_<parameter> <value>

Prepend set_ or get_ to parameter, to tell daemon if parameter should be read or set.

DaemonCLI image_sensor set_gain 2

6.1 Available modules

general General methods, like getting available parameters through get_available_methods
image_sensor CMV12000 (currently)

6.2 Available parameters (per module)


gain Digital gain

7 Development notes

CMV12000Adapter will be used as example. Please look at the class for examples of implementation.

7.1 Add new parameters

Before registering new parameters, two methods should be added: a setter and a getter.

Declaration syntax:

   bool <setter_name>(std::string value1, std::string value2, std::string& message)
bool <getter_name>(std::string& value, std::string& message)

Note the ampersand (&) after the type, it is very important for returning multiple values. As methods can return only one value, bool in this case, variables can be passed by reference (&) to be able to set their values inside methods. Values can be modified as usual and the value will be passed back to the caller (see IDaemonModule.h and MessageHandler.cpp for examples).

Setter receives two values, in case just one is required value2 will be 0 (zero).

After the setter and getter are implemented, it's time to attach them to a parameter name. Here they are registered to gain parameter:

 void CMV12000Adapter::RegisterAvailableMethods()
  AddParameterHandler("analog_gain", GETTER_FUNC(&CMV12000Adapter::GetAnalogGain), SETTER_FUNC(&CMV12000Adapter::SetAnalogGain));
  AddParameterHandler("digital_gain", GETTER_FUNC(&CMV12000Adapter::GetDigitalGain), SETTER_FUNC(&CMV12000Adapter::SetDigitalGain));

This code will attach methods like SetAnalogGain() and GetAnalogGain() to the corresponding parameter "analog_gain".

8 Unit tests

Unit tests have been added to the project to verify correct functionality. Catch2 framework is used because it's single-header only and utilizes the C++11 way of doing things.

Note: (for development on PC) - RAM access of the camera is different from x86/x64 CPUs, modified classes have to be used to bypass this, otherwise SEGFAULT would be the result.

In the CMake scripts a switch called ENABLE_MOCK was added so that users can disable any code which won't work on a regular PC (see CMV12000AdapterTests.cpp for an example). While running the build on camera cmake .. is sufficient, but for development one should use:

$ cmake -DENABLE_MOCK=ON ..