Ethernet Functional Test & Fault Isolation
Kozio provides a complete functional Ethernet test for validating the entire circuit board path. The VTOS Scan Ethernet product provides configurable packet testing, packet data verification, speed testing, single port testing, multiple port testing, and exceptional fault isolation.
- Individual test for all speeds: 10, 100, Gigabit, 10 Gigabit
- Configurable packet testing with packet data verification
- Internal, PHY, and external packet testing
- Single port, multiple port, and switch configuration handling
- Port loopback and port to port validation
- Configurable MAC Address, IP Address, and LAN troubleshooting commands
Simple Ethernet Test Configuration
Kozio provides embedded run-control software that runs on your circuit board design without modification. The firmware is loaded through JTAG, serial, USB, or SD Card – depending on which processor your design uses. Kozio also provides PC software that provides user interfaces for test development and automated test execution. The solution works with a variety of JTAG adapters, Boundary Scan hardware, or simple communication interfaces such as serial or USB.
The block diagram below illustrates a couple common Ethernet designs, incorporating a single port and multiple ports. Click on the image to enlarge.
The VTOS Developer user interface provides a number of features to make Ethernet test configuration easier.
- Pin Configuration Files – VTOS Scan Ethernet will import pin mux files generated by popular pin mux configuration tools – those pin mux tools provided by the processor manufacturer – making it easy to configure for designs using an ARM® processor.
- PHY Discovery – VTOS Scan Ethernet will automatically scan, discover, and add tests for every discovered PHY. No need to dig through schematics and hardware documents, simply run the “Scan & Add” functions provided. The report generated after scanning displays PHY details such as bus, address, and identifier.
- MAC & PHY Configuration – Based on your chosen processor, only the supported MII types are presented. The PHY addresses can be discovered through the automatic scan operation.
- Test Configuration – Quickly add tests to run at the various supported speeds and adjust the number of packets that will be sent, received, and verified. Add a test to verify PHY access and also verify that the correct PHY has been placed on the newly manufactured board. This simple test can detect counterfeit parts or incorrect parts.
- Expert Level Features – Each test item can be modified to run special commands before or after the test. The “Setup Actions” and “Cleanup Actions” are available for every test item in the configuration tree. If your circuit board design requires special handling for PHY enabling, signalling, or power, those steps can be included through setup or cleanup actions. Custom board initialization scripts can also be added quickly, and with help from Kozio’s technical support. Advanced commands are documented in the VTOS Tools Command Reference document and can be executed through the user interfaces’s advanced mode.
Here is a few screen shots of VTOS Scan Ethernet in action, using the test development user interface, Click on any image to enlarge.
Single Port Testing
VTOS Scan Ethernet provides multiple test steps for better fault isolation. The overall process used to functionally test the hardware is to fill Ethernet packets with well-known data, send the packet, receive a packet, and then verify that the packet data was returned without data errors. This process is repeated multiple times based on user configuration data.
The first test to run is an internal MAC packet test. This test verifies a correct MAC configuration and a properly functioning Media Access Control unit. Packets are sent to the MAC and received back from the MAC. In this example, this will verify communications from the CPU to MAC1. The port testing descriptions refer back to the block diagram presented earlier.
The next step is to verify data and control lines to the PHY. You should run a “PHY Verify Test” to ensure the correct part was used, and then run PHY packet testing at all supported speeds. The “PHY Loopback Test” verifies the MII interface from MAC1 to the PHY and also verifies the MDIO/MDC interface to the PHY. This step isolates signalling errors over the two different bus interfaces. Add multiple tests, one for each speed you wish to test.
The last step is to run an “External Loopback Test“. This test requires a loopback connector, or loopback signaling on a fixture, for proper execution. Add multiple tests, one for each speed you wish to test. This test verifies the magnetics, connector, and off-board signalling. Running multiple tests, and different speeds, will also isolate faulty signals specific to Gigabit Ethernet.
VTOS Scan Ethernet provides the ability to test multiple ports presented through a switch. You have the capability to test your circuit board design by sending Ethernet packs from processor memory, through a single port on the switch, off-board, and then back again to processor memory. The overall process used to functionally test the hardware is to fill Ethernet packets with well-known data, send the packet, receive a packet, and then verify that the packet data was returned without data errors. This process is repeated multiple times based on user configuration data.
For multiple port testing, Kozio Script commands are used to communicate with the switch. The exact commands used will vary per switch, so the custom scripting capabilities of VTOS provide an excellent way to add new switch commands without requiring updates from Kozio. Multi-port testing will work with any switch that provides an “unmanaged” option. An unmanaged switch allows Ethernet devices to communicate with one another, which allows us to test each port and corresponding PHY/RJ45 separately.
The general process is to use a Kozio Script file to communicate with the switch and enable one port and disable all other ports. This step is repeated for each of the four ports as pictured in our example block diagram. For example, Port 2 is enabled, and Ports 3, 4, and 5 are disabled. You then run multiple Ethernet Loopback Tests for all supported speeds. This step verifies communications from MAC2 to Port 1 to Port 2 and the corresponding PHY and RJ45 connector. This process is then repeated to test Port 3, then Port 4, and finally Port 5. In this manner, each port is testing and any faults are isolated to the fewest components as possible.
This process also works for Fibre connections, but they were not pictured in order to keep the diagram simple.
Another feature provided by VTOS Scan Ethernet is the ability to test two connectors or ports simultaneously. An option is provided so that you can use an Ethernet cable to connect two ports together, and then run an External Loopback Test to test packet transmissions through both ports. In some production test situations, this may be more desirable than using loopback plugs for each port.
Ethernet Fault Isolation
VTOS Scan Ethernet provides several tools to validate all aspects on on-board and off-board electronics – all completed at full processor speeds utilizing fast processor memory.
Use the automatic PHY discovery feature to add tests to verify communications to all PHYs as well as verifying their manufacturer identifiers. The MAC Loopback Tests provide a second verification step to verify communications to all Media Access Control devices. The PHY loopback tests verify MDIO and MII bus interfaces. And the External Loopback Test verifies the remaining path including testing off-bard signaling.
Using the Advanced Mode, you can use commands to verify a LAN connection. Commands are provided to set your MAC and IP addresses, and then perform an ARP discovery and ICMP verification using the “ping” command. These commands are helpful when troubleshooting communication issues between your target and a PC, especially when using Kozio’s Fast Flash Programming feature with Ethernet file transfers.
After you have used VTOS Developer to create the test sequence that meets your Ethernet testing requirements, export all test configuration information for automated execution. Kozio provides a VTOS Runner tool that will execute the test configuration you developed, along with executing other tests and flash programming. Use the “Export » Kozio Script File” to export the file needed by VTOS Runner.
The VTOS Developer GUI also provides a feature to “Export » Desktop Shortcut“. That option will export all required data and place a button on your desktop. Double-click on the button and your Ethernet test sequence is automatically executed. All Kozio files exported by are human readable.
Use the “Export » NI TestStand Sequence” option to export your Ethernet test configuration directly into an NI TestStand sequence file. The sequence file (*.seq) created can be opened and executed in TestStand without modification.