Communication module

What makes a module?

A module has two important moving parts:

• The communication module that is given to the constructor.
• The process function.

The process function has to return. It is the responsibility of the owning code to call process repeatedly. This allows multiple modules on a single system.

The basic template for a module is as follows:

#include <base_module.hpp>

namespace r2d2::module_name {
    class module_c : public base_module_c {
    public:
        /**
         * @param comm
         */
        module_c(base_comm_c &comm) 
            : base_module_c(comm) {
            comm.listen_for_frames(
                // Array of frames
            );
        }

        /**
         * Let the module process data.
         */
        void process() override {
            // Ask the button module for the button state
            while (comm.has_data()) {
                auto frame = comm.get_data();

                // Process the frame
            }
        }
    }
}

In the constructor, the listen_for_frames method of the communication instance should be called. This will instruct the communication system to deliver these message types to your module.

You need to specifiy frames you want to receive. This is also the case for requests. Please look at the examples folder for more usage examples.

Request data from the bus

The following code should be used to request data from the bus:

// Frame type enum (e.g. frame_type::BUTTON_STATE)
comm.request(frame_type); 

Processing a request from the bus

If your module receives requests from the bus, it should process them in the process function as follows:

while (comm.has_data()) {
    auto frame = comm.get_data();

    // Only handle requests
    if (!frame.request) {
        continue;
    }

    // Process request
}

Send data on the bus

Use the following code to send data on the bus:

    // Get button state, create frame and send
    packet_button_state_s button_state;

    button_state.pressed = button.read();

    comm.send(button_state);

Examples

Usage examples can be found in the "examples" folder. Each subfolder in an example represents a module. These examples are updated to represent the latest version of the library.