How to integrate C2A

1. Overview

• C2A (Command Centric Architecture) is an architecture for spacecraft flight software developed by ISSL.
• S2E can execute C2A as flight software for onboard algorithm development and debugging.
• This document describes how to integrate the C2A within S2E.
• Notes
  • C2A is written in C language, but S2E builds C2A as C++.
• The supported version of this document
  • Please confirm that the version of the documents and s2e-core are compatible.

2. Overview of C2A execution in S2E

• Directory Construction
  • Make FlightSW directory at same directory with s2e-core and s2e-user.
  • Make a c2a-user directory in FlightSW and set the C2A source code you want to use.

    ├─ FlightSW
    │  └─ c2a-user
    │    └─ src_user
    │    └─ src_core
    └─ s2e-user-example
      ├─ s2e-core
      └─ ExtLibraries
    

  • Edit s2e-user/CMakeLists.txt as follows.
    • set(C2A_NAME "c2a_oss")
      • Edit the directory name c2a_oss according to your situation.
      • In the case of the above directory structure, you need to edit as c2a-user
    • option(USE_C2A "Use C2A" OFF)
      • Turn on the USE_C2A flag as option(USE_C2A "Use C2A" ON)
• Notes
  • In the default setting of S2E, C2A is built but isn't executed. To execute the C2A, users need to add an onboard computer, which can execute the C2A.
  • The s2e-core has the ObcWithC2a class as a component, and users can use it to execute the C2A.
  • Users can use the ObcWithC2a class in the UserComponents class, the same as other components.
• Build the s2e_user
  • Note: When you add new source files in the C2A, you need to modify the c2a-user/CMakeLists.txt to compile them in the S2E.
  • Users can choose the construction of CMake as users need. For example, the sample codes have several CMakeLists.txt files in each directory to set the compile targets, so users need to modify them to add the target source codes.

3. How to build C2A in S2E with the sample codes

• Sample codes

  • A sample of s2e-user: s2e-user-example/sample/how-to-integrate-c2a
  • A sample of c2a-user: C2A minimum user in c2a-core.

• Preparing development environment

  • Clone the s2e-user-example and switch the branch to sample/how-to-integrate-c2a.

  • Make FlightSW directory at same directory with s2e-core.

  • Clone c2a-core v3.8.0 in the FlightSW directory.

  • Execute setup script

    • Mac or Linux Users: c2a-core/setup.sh
    • Windows Users: c2a-core/setup.bat

  • Open s2e-user-for-c2a-core/CMakeLists.txt and edit set(C2A_NAME "c2a_sample") to set(C2A_NAME "c2a-core/Examples/minimum_user")

  • For users who don't use Windows

    • open c2a-core/Examples/minimum_user/CMakeLists.txt and edit option(USE_SCI_COM_WINGS "Use SCI_COM_WINGS" ON) to option(USE_SCI_COM_WINGS "Use SCI_COM_WINGS" OFF)
    • This setting turns off the feature to communicate with WINGS ground station. Currently, this feature is available only for Windows users.

  • Please check the following directory construction

    ├─ FlightSW
    │  └─ c2a-core
    │    └─ Examples
    │      └─ minimum_user
    └─ s2e-user-example
      ├─ s2e-core
      └─ ExtLibraries
    

  • Build and execute the s2e-user-example.

  • Users can see the following output in a terminal. The CYCLE: TOTAL value is incremented.

    

4. Communication between C2A and S2E for SILS test

• Generally, communication between flight software and S2E is executed via OnBoardComputer class.
• The OnBoardComputer class has communication ports and communication functions. Other components and flight software can use the communication functions to communicate each other.
• For C2A, the ObcWithC2a has the following functions for C2A flight software. The driver functions in the flight software can use these functions. It is essential to use the same port_id with the component setting in S2E. The details are described in specification documents for each feature.
  • Serial communication functions

    int OBC_C2A_SendFromObc(int port_id, unsigned char* buffer, int offset, int count);
    int OBC_C2A_ReceivedByObc(int port_id, unsigned char* buffer, int offset, int count);
    

  • I2C communication functions

    int OBC_C2A_I2cWriteCommand(int port_id, const unsigned char i2c_addr, const unsigned char* data, const unsigned char len);
    int OBC_C2A_I2cWriteRegister(int port_id, const unsigned char i2c_addr, const unsigned char* data, const unsigned char len);
    int OBC_C2A_I2cReadRegister(int port_id, const unsigned char i2c_addr, unsigned char* data, const unsigned char len);
    

  • GPIO

    int OBC_C2A_GpioWrite(int port_id, const bool is_high);
    bool OBC_C2A_GpioRead(int port_id);
    

• Currently, the C2A uses the wrapper functions in IfWrapper/Sils. The functions automatically overload the normal IfWrapper functions when C2A is executed on the S2E.
• Other interfaces like SPI, etc., will be implemented.

5. Example of S2E-C2A communication

• This section shows an example of communication between a component in S2E and an application in C2A.

• The sample codes

  • S2E: s2e-user-example/sample/how-to-integrate-c2a
  • C2A: Tutorials/SampleCodes/c2a_integration/

• Preparation

  • See Ch. 3 How to build C2A in S2E with the sample codes.

• Modification of the S2E side

  • Users can use the ExampleSerialCommunicationWithObc class in s2e-core as a test component to communicate with C2A.
  • Please refer the sample codes in s2e-user-example/sample/how-to-integrate-c2a.
  • Add ExampleSerialCommunicationWithObc as a component in user_components.cpp and .hpp.
    • In this example, the ObcWithC2a is executed as 1kHz, and the ExampleSerialCommunicationWithObc is executed as 1Hz.

• Modification of the C2A side

  • Please refer the sample codes in Tutorials/SampleCodes/c2a_integration/c2a_src_user.
    • The directory structure of c2a_src_user is the same with that of c2a-core/Examples/minimum_user/src/src_user.
  • We need to add a new driver instance application to communicate with the ExampleSerialCommunicationWithObc component.
    • Copy Application/DriverInstances/di_s2e_uart_test.c and .h
    • Edit CMakeLists.txt in the Application directory to add di_s2e_uart_test.c as a compile target.
  • Edit app_registry.c, h and app_headers.h in the Application directory to register the applications of di_s2e_uart_test.
    • We have two applications AR_DI_S2E_UART_TEST and AR_DI_DBG_S2E_UART_TEST.
  • Edit Setting/Modes/TaskLists/Elements/tl_elem_drivers_update.c to add the AR_DI_S2E_UART_TEST to execute the application in the tasklist.
  • Edit Setting/Modes/TaskLists/Elements/tl_elem_debug_display.c to add the AR_DI_DBG_S2E_UART_TEST to execute the application in the tasklist.

• Execution and Result

  • The C2A's AR_DI_S2E_UART_TEST application sends characters to the S2E's ExampleSerialCommunicationWithObc component like SETA, SETB, SETC, ..., SETZ, SETA

  • The ExampleSerialCommunicationWithObc component receives the characters and stores the set characters like A, B, C, ..., Z, A

  • The ExampleSerialCommunicationWithObc component sends the stored characters as telemetry like A, BA, CBA, ..., ZYX

  • The AR_DI_S2E_UART_TEST application receives the telemetry, and the AR_DI_DBG_S2E_UART_TEST application prints the first three characters in the debug output console like the following figure.