SPRACM3E August   2021  – January 2023 TMS320F280021 , TMS320F280021-Q1 , TMS320F280023 , TMS320F280023-Q1 , TMS320F280023C , TMS320F280025 , TMS320F280025-Q1 , TMS320F280025C , TMS320F280025C-Q1 , TMS320F280033 , TMS320F280034 , TMS320F280034-Q1 , TMS320F280036-Q1 , TMS320F280036C-Q1 , TMS320F280037 , TMS320F280037-Q1 , TMS320F280037C , TMS320F280037C-Q1 , TMS320F280038-Q1 , TMS320F280038C-Q1 , TMS320F280039 , TMS320F280039-Q1 , TMS320F280039C , TMS320F280039C-Q1 , TMS320F280040-Q1 , TMS320F280040C-Q1 , TMS320F280041 , TMS320F280041-Q1 , TMS320F280041C , TMS320F280041C-Q1 , TMS320F280045 , TMS320F280048-Q1 , TMS320F280048C-Q1 , TMS320F280049 , TMS320F280049-Q1 , TMS320F280049C , TMS320F280049C-Q1 , TMS320F28384D , TMS320F28384S , TMS320F28386D , TMS320F28386S , TMS320F28388D , TMS320F28388S , TMS320F28P650DK , TMS320F28P650SH , TMS320F28P650SK , TMS320F28P659DK-Q1

 

  1.   Using the Fast Serial Interface (FSI) With Multiple Devices in an Application
  2.   Trademarks
  3. 1Introduction to the FSI Module
  4. 2FSI Applications
  5. 3Handshake Mechanism
    1. 3.1 Daisy-Chain Handshake Mechanism
    2. 3.2 Star Handshake Mechanism
  6. 4Sending and Receiving FSI Data Frames
    1. 4.1 FSI Data Frame Configuration APIs
    2. 4.2 Start Transmitting Data Frames
  7. 5Daisy-Chain Topology Tests
    1. 5.1 Two Device FSI Communication
      1. 5.1.1 CPU Control
      2. 5.1.2 DMA Control
      3. 5.1.3 Hardware Control
    2. 5.2 Three Device FSI Communication
      1. 5.2.1 CPU/DMA Control
      2. 5.2.2 Hardware Control
        1. 5.2.2.1 Skew Compensation for Three Device Daisy-Chain System
          1. 5.2.2.1.1 CPU/DMA control
          2. 5.2.2.1.2 Hardware Control
  8. 6Star Topology Tests
  9. 7Event Synchronization Over FSI
    1. 7.1 Introduction
      1. 7.1.1 Requirement of Event Sync for Distributed Systems
      2. 7.1.2 Solution Using FSI Event Sync Mechanism
      3. 7.1.3 Functional Overview of FSI Event Sync Mechanism
    2. 7.2 C2000Ware FSI EPWM Sync Examples
      1. 7.2.1 Location of the C2000Ware Example Project
      2. 7.2.2 Summary of Software Configurations
        1. 7.2.2.1 Lead Device Configuration
        2. 7.2.2.2 Node Device Configuration
      3. 7.2.3 1 Lead and 2 Node F28002x Device Daisy-Chain Tests
        1. 7.2.3.1 Hardware Setup and Configurations
        2. 7.2.3.2 Experimental Results
      4. 7.2.4 1 Lead and 8 Node F28002x Device Daisy-Chain Tests
        1. 7.2.4.1 Hardware Setup and Configurations
        2. 7.2.4.2 Experimental Results
      5. 7.2.5 Theoretical C2000 Uncertainties
    3. 7.3 Additional Tips and Usage of FSI Event Sync
      1. 7.3.1 Running the Example
      2. 7.3.2 Target Configuration File
      3. 7.3.3 Usage of Event Sync for Star Configuration
  10. 8References
  11. 9Revision History

6 Star Topology Tests

The star topology over FSI application example demonstrates a different kind of communication topology, showcasing how a central host device can receive information from multiple node devices at the same time rather than wait for packets to be forwarded through subsequent devices, like in the daisy-chain example. The advantages and disadvantages of the star topology are discussed in Section 2.

The defining requirements of the star implementation provided are hardware related, i.e. host device TX needing to have multi-drop functionality to each node, and MCU resource related, i.e. host device needing N number of RX instances. From a software perspective the central host device uses a new star_broadcast project while the N node devices use the same node device software utilized in the daisy-chain tests, details provided in Table 6-1.

Table 6-1 Software Example Projects - Star Topology
Project Description Supported Devices
fsi_ex_star_broadcast Project for central host device in the star network F2838x
fsi_ex_daisy_handshake_node Project for N number of node devices in the star network F28002x, F28004x, F2838x

The software flow of the star_broadcast project is similar to that of the lead device CPU Control daisy-chain project discussed in Section 5. The handshake mechanism is slightly different as shown in Section 3.2. Upon completion of the handshake, the central host device transmits a broadcast data frame to all of the node devices connected to its FSITX. The host then waits to receive the data frame back from all connected node devices and then validates that each received frame matches the originally transmitted one, after which it prepares and sends a new data frame.

By default, the star_broadcast project has pre-made configurations for FSI RX instances A, B and C of the device. Each instance can be configured by setting the individual pre-processor directives below to "1". Additional FSI RX instances can be added if they are available on the host device.

//
// Enable FSI RX Instances
//
#define FSI_RXA_ENABLE          1
#define FSI_RXB_ENABLE          0
#define FSI_RXC_ENABLE          1

Timing measurements of the star topology are very similar, if not the same, as those collected in the previous daisy-chain tests. Therefore, the data provided in Table 5-4 can be utilized for this purpose.