Taking Automotive Ethernet for a Test Drive

Taking Automotive Ethernet for a Test Drive

Automotive Ethernet employs a unique interface that requires new testing protocols and test equipment.

Automotive Ethernet was a hidden gem at the Consumer Electronics Show, but it will be much more noticeable at this year’s show. It’s also something supported by major test and measurement vendors, because not all Ethernet tools will work with the new standards.

The standards include IEEE 802.3bw 100BASE-T1 and IEEE P802.3bp 1000BASE-T1. These adopt the 100-Mb/s and 1-Gb/s Ethernet protocols we have come to know and love. They run over a single twisted pair and can have up to four inline connectors, sans the endpoints. There’s a tradeoff, though: The run length is only 15 m. Still, that’s more than enough to handle most automotive and many transportation applications.

Automotive Ethernet will replace the Media Oriented Systems Transport (MOST) bus found on many vehicles today. It will also compete with systems like Maxim Integrated Products’ Gigabit Multimedia Serial Link (GMSL).

Chips and PHYs are now readily available for automotive Ethernet, as are switches. For instance, Marvell’s 8-port, 88Q5050 Secure network switch supports the 100Base-T1 standard, as well as time-sensitive networking (TSN). Audio video bridging (AVB) ingress policy and rate limiting are part of TSN. The switch also features 802.1Qav/Qbv queue-shaping support for AVB and TSN.

The 88Q5050 is compatible with IEEE 802.1AS time-synchronization protocols like the precision time protocol (PTP), aka IEEE 1588. These timing standards can be found on conventional Ethernet networks, too, but they highlight why the test and measurement tools need to be more sophisticated.

Put to the Test

1. Tektronix’s 8-channel 5 Series MSO has a large, 15.6-in. capacitive touch display, 12-bit resolution, and bandwidth up to 2 GHz.

Tektronix’s 8-channel, 5 Series MSO (mixed-signal oscilloscope) has a large, 15.6-in. capacitive touch display (Fig. 1). The scope’s 12-bit analog-to-digital converters (ADCs) can deliver up to 16 bits of vertical resolution; systems are available with a bandwidth from 350 MHz to 2 GHz. The sample rate on all channels is 6.25 Gsamples/s. Pricing starts at $12,000.

The 5 Series MSO systems utilize FlexChannel inputs (Fig. 2). These combine an analog BNC connector with eight digital inputs. The combination of inputs employed will depend on the probe that’s plugged into the socket. The BNC connector can be used directly for coax inputs as well. The 8-input 5 Series MSOs provide up to 64 digital inputs.

2. The FlexChannel sockets developed by Tektronix sport eight digital inputs and one high-resolution analog input.

The 5 Series MSO has two option packages for the automotive market. The 5-SRAUTO protocol option package addresses standards like CAN, CAN FD, LIN, and FlexRay. This includes CAN FD support for non-ISO and ISO versions of the standard. The systems provide complete serial triggering and analysis of these major buses.

The 5-CMAUTOEN Automotive Ethernet package targets the automotive Ethernet standards. An automated compliance solution includes test software that runs while performing Physical Media Attachment (PMA) transmitter Group 1 electrical measurement compliance tests, as defined by the OPEN Alliance Special Interest Group (SIG) standard for automotive Ethernet.

3. Rohde & Schwarz’s RTO digital oscilloscopes support automotive Ethernet testing.

The RTO digital oscilloscopes (Fig. 3) from Rohde & Schwarz are capable of automotive Ethernet testing. Versions with up to four analog channels are available with bandwidths that range from 600 MHz to 6 GHz. The sample rate is 20 Gsamples/s with 16-bit vertical resolution.

The RTO scopes can be combined with triggering and decoding support for LIN, CAN, CAN-FD, and FlexRay. The R&S RTO-K24 compliance test option addresses 100Base-T1, while the RTO-K87 compliance test option addresses 1000Base-T1.

4. Bundled hardware and software solutions from Keysight Technologies address the automotive test and measurement market.

Keysight Technologies has bundled hardware and software solutions for the automotive market (Fig. 4). The bundles can support automated setup and testing for the transmitters, receivers, and link segments. They’re able to handle BroadR-Reach (that the standards were based on), 100Base-T1, and 1000Base-T1. This includes end-to-end functional and standards-compliance conformance testing support.

5. The 4-channel, 2.5-GHz DSOS254A is part of one of Keysight’s automotive bundles.

The bundles come with a number of hardware components, such as the DSOS254A oscilloscope (Fig. 5), the 44-GHz N9010A EXA signal analyzer, and the 2-channel 81150A pulse-function arbitrary noise generator. The DSOS254A is a 4-channel, 2.5-GHz scope with a 15-in. touchscreen display. The system operates at 20 Gsamples/s using a 10-bit ADC.

TAGS: Automotive
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