4.1.2. CAN to ethernet Gateway demo¶

4.1.2.3.1. Assumptions¶

• Basic familiarity with operating any CAN device capable of sending and receiving CAN-FD messages. This includes knowledge of wiring and signals. In this demo the PCAN tool is used to show the same.
• Basic familiarity with Ethernet interface and IEEE 1722 protocol
• Knowledge of raw sockets is helpful, but not essential
• Operation of a PC/System running Linux. Since raw sockets are used, Windows is not supported.
• Basic familiarity with Jacinto 7 Architecture. Things like MCAN, MCU Island etc. Readers are asked to read SoC documentation first if they haven’t done so already.

4.1.2.3.2. Hardware¶

• J721E EVM Board (SOM Board and Common Board).
• CAN Receiver/Transmitter with minimum of 2x ports and a GUI to display messages. This demo shows this with 2x PCAN tools, but it can be ideally be any tool. Refer to PCAN tool setup section for further details.
• 1x LAN Cables (preferably CAT6)
• 2x Micro USB cable (for UART and JTAG)
• SD card. (This is the recommended boot option)
• Linux PC with minimum of 1x Gigabit port and root access
  • Important - Root access is required because the demo uses raw sockets, and raw sockets are only accessible with root privileges.
• Windows PC to run PCAN-View software. PCAN-View is also available on Linux but not used in this demo. It’s also possible that user may choose to use a different PCAN device, in which case this is optional.

4.1.2.3.3. Software¶

• Code Composer Studio (CCS) version 9.0.1.00004. (Optional if SD card is not available)

• PC Ethernet tools - Required for receiving and transmitting data over Ethernet

  • Use/run recv_1722.out, send_1722.out and control_gateway_app.out utilities on host PC. These utilities are available at:

    <SDK_INSTALL_PATH>/gateway-demos/pctools
    

• CAN tool software (PCAN drivers and PCAN View if using PCAN-USB tool)

4.1.2.10.1. J721E Board Setup¶

Conceptually the wiring should be done as shown below:

When actual connections are made it looks like below:

4.1.2.10.1.2. MCAN Setup¶

As shown in the picture, connect the two USB-CAN analyzers to MCAN0 and MCAN1 instances, which are labeled as J30 and J32 respectively on the J721E base EVM board. The MCAN pin connection is as follows:

• Pin 1 (CAN_H)
• Pin 2 (GRD)
• Pin 3 (CAN_L)

The following diagram shows the MCAN0 and MCAN1 connections on base EVM.

If using PCAN tool, the DB-9 connection is as follows:

Use below image as reference to connect the wires.

4.1.2.10.2. PCAN Tool Setup¶

The PCAN-USB FD tool has been used to validate this demo. This tool provides a connection of CAN FD and CAN networks to a computer through USB.

For further information on the PCAN-USB product, please visit the manufacturer’s website: https://www.peak-system.com/PCAN-USB-FD.365.0.html?&L=1

1. Prerequisite (PC setup):

   • Download and install PCAN driver from: https://www.peak-system.com/quick/DrvSetup
   • Download PCAN-View from: https://www.peak-system.com/fileadmin/media/files/pcanview.zip

2. PCAN Setup:

   • PCAN-View is a GUI-based tool used to configure bit-rate of the PCAN tool. It provides a convenient was to see sent and received messages. It also provides an option to enable tracing of CAN messages along with timestamp. Please refer to PCAN-USB FD manual for more details.

   • Once driver is installed, connect the PCAN device to PC. It should be auto detected as PCAN-USB FD in Windows’ Device Manager. If it is not auto detected, try re-installing the PCAN driver.

   • Open PCAN-View and follow below steps:

     • Click on Connect from CAN menu (as shown in below figure)

       • Pop-up window shall show connected PCAN hardware. Select the desired device.

       • Enable the Data Bit rate checkbox. This will enable Bit rate selection from a drop down menu

       • Select Nominal Bit Rate as 1 MBits/s

       • Select Data Bit Rate as 5 MBits/s. If this bit-rate is not listed in your menu refer to ‘Creating Bit Rate Configurations’ step below for creating custom bit rate.

         • Note: Bit rates may vary from use-case to use-case based on MCAN configuration on the J721E side.

       • Click on OK button.

       

     • Create and send message at period of 1 ms

       • Click on New Message under Transmit menu

       • Enable the CAN FD checkbox

       • Enable the Bit Rate Switch checkbox

       • Set the following parameters in the New Transmit Message window:

         • ID as hex 000000C0 for MCAN0 and 000000B0 for MCAN1
         • Length as 64
         • Cycle Time as 1
         • Data can be selected randomly

       

3. Creating Bit Rate Configurations

   • Create a 5 Mbps bit rate configuration for Data Bit Rate (shown in below diagram)

     • Click on Connect under CAN menu

     • Enable the Data Bit rate checkbox

     • Click on the Play button below Data Bit rate and then Manage Bit rates. This will open a pop-up window

     • Click on Data in the Manage Bit Rates window

     • Select Clock Frequency as 80 MHz

     • Click on Add button

     • Set the new bit rate parameters as follows:

       • Caption to 5 MBits/s
       • Prescalar to 1
       • tseg1 to 12
       • tseg2 to 3
       • Sync Jump Width to 1

     • Bit Rate textbox shall show 5 Mbit/s after programming above values.

     • Click on OK and then again on OK

   

4. CAN Bus Connections - Please refer to the PCAN-USB FD manual for more details about connections.

5. CAN Bus Connections (applies if single PCAN device is used for 2 CAN’s using breadboard):

   • CAN_H of all the nodes on the bus shall be connected together
   • Similarly, CAN_L of all the nodes on the bus shall be connected together

4.1.2.10.3. Load and Run the Demo¶

4.1.2.10.3.1. CCS Boot¶

For more details about installation of CCS and J721E target creation, refer to “Ethernet Firmware_CCS setup.pdf” user guide at installer folder.

1. Connect a micro USB cable to JTAG port of J721E_EVM. The XDS110 JTAG connector is labeled XDS110 (J3).

2. Connect a micro USB cable to MCU Domain UART port on J721E_EVM. It’s labeled MCU UART (J43).

3. Set EVM’s DIP switches SW8 and SW9 for no-boot mode:

   • SW8 = 10001000
   • SW9 = 01110000

4. Power on the J721E EVM board. Ensure that SD card is not present or QSPI flashed.

5. Open up a serial terminal to ttyUSB1 for UART communication. This will show logs from MCU1_0 core where the demo application runs.

   • Set serial parameters to: 115200 8N1.
   • Set hardware and software flow control to “No”.
   • Below figure shows serial parameters set in Minicom.

   

6. Open CCS and launch target config file for J721E_EVM.

7. Load the System firmware using launch script provided with this package.

8. Wait for initialization and then connect to MCU domain R5F_0_1.

9. Load and launch the demo executable:

   <SDK_INSTALL_PATH>/binary/gatewayapp/bin/j721e_evm/gatewayapp_mcu1_0_release.xer5f
   

10. The application should boot up with the console log shown below. Note that the Ethernet interface takes a few seconds to come up.

4.1.2.10.3.2. SD Card Boot¶

1. Create a bootable SD card with SBL bootloader and System Firmware. For details about SD card creation, refer to the Processor SDK RTOS Automotive User’s Guide.

2. Copy the CAN/Eth gateway demo application to the /boot folder in SD Card and rename it to app.

3. Connect a micro USB cable to MCU Domain UART port on J721E_EVM. It’s labeled MCU UART (J43).

4. Set EVM’s DIP switches SW8 and SW9 for SD card boot:

   • SW8 = 10000010
   • SW9 = 00000000

5. Open up a serial terminal to port ttyUSB0 for UART1 communication. This terminal will show logs from system firmware.

   • Set serial parameters to: 115200 8N1.

6. Open up a serial terminal to port ttyUSB1 for UART2 communication. This terminal will show logs from MCU1_0 core where the demo application runs.

   • Set serial parameters to: 115200 8N1.
   • Set hardware and software flow control to “No”.
   • Below figure shows serial parameters set in Minicom.

   

7. Insert SD card into slot labeled MICRO SD and power-on the J721E EVM board.

8. The application should boot up with a console log as shown below:

4.1.2.10.4. Routing¶

The demo performs three kinds of routing, CAN-to-CAN, CAN-to-Eth and Eth-to-CAN. The behavior can be controlled by PCAN tool and PC tools provided along with the demo sources.

4.1.2.10.4.1. Eth to CAN¶

Eth-to-CAN direction involves the following routes:

Route	Source	Destination	Message ID
Eth -> Gateway -> MCAN0 -> PCAN1	Eth	PCAN 1	0xD0
Eth -> Gateway -> MCAN1 -> PCAN2	Eth	PCAN 2	0xE0
Eth -> Gateway -> MCAN0+1-> PCAN1+2	Eth	PCAN 1+2	0xF0

Follow the next steps to test Eth-to-CAN routes:

1. In Linux PC, open console and run:

   cd <SDK_INSTALL_PATH>/gateway-demos/pctools
   sudo ./send_1722.out <eth_interface> 1 MCAN0
   

Where <eth_interface> is the name of ethernet interface on the Linux PC. On most PC’s it’s either eth0 or eth1 but it can be anything and thus no standard convention. 1 is the number of messages to be sent and MCAN0 indicates that a CAN ID of 0xD0 should be embedded inside the 1722 message.

This will send one 1722 message with CAN ID of 0xD0. When gateway demo sees this message, it will route it to MCAN0 interface.

1. Now try the same command with MCAN1 option:

   sudo ./send_1722.out <eth_interface> 1 MCAN1
   

2. Finally, route the packet to both interfaces with the command:

   sudo ./send_1722.out <eth_interface> 1 BOTH
   

3. A screenshot of send_1722.out console application is shown below:

4.1.2.10.5. Statistics¶

Since gateway demo is an application which runs in a forever loop waiting for frames, it’s not possible to show stats periodically, as it would impact performance. To workaround this problem, a separate console application called ``control_gateway_app.out ``is provided which sends a signal to the application to print statistics. To run the app use the command below:

cd <SDK_INSTALL_PATH>/gateway-demos/pctools sudo ./control_gateway_app.out <eth_interface> stat

control_gateway_app.out provides two options to the user: kill and stat (both are documented inside the application). When stat is used, the demo application prints performance and statistics including CPU Load.

kill kills the application (it’s reserved for future use)

See figure below:

4.1.2.10.6. Known issues & limitations¶

1. Polling mode is not supported in Gateway application

2. Due to simultaneous Rx and Tx, the CAN-USB Tool might go into an error state. When this happens the CAN-USB Tool blinks red constantly and no CAN messages are seen on the bus. To recover, first Disconnect (Ctrl + D) and then Connect (Ctrl + B) the device. See below: