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Tesla really deserves some kudos for pushing the 48V architecture and the Ethernet-based communication. It drastically simplifies the wiring mess that is in a t
by cyberax 2y ago
Tesla really deserves some kudos for pushing the 48V architecture and the Ethernet-based communication. It drastically simplifies the wiring mess that is in a typical car.
And it's not even close. Just watch the teardown of Cybertruck and compare its wiring to something like F150.
- outworlder 2y agoWe can simplify the wire mess today by using more CAN bus devices. What is ethernet bringing to the picture?
- the_mitsuhiko 2y agoCentral bus instead of many point to point connections. Look at how much fewer cabling the cybertruck has.
- mulmen 2y agoBandwidth?
- KK7NIL 2y ago> What is ethernet bringing to the picture? Over 3 orders of magnitude faster datarates. CAN FD: up to 5Mb/s Automotive Ethernet: up to 10 Gb/s
- gregoriol 2y agoWhy would you need 10 Gb/s speeds in a car
- the_mitsuhiko 2y agoWhy would you not? Tesla is sending even the infortainment data stream through that bus. It's incredibly helpful having all data travel on a singular wire because you can tap in at one point and read it all out. Makes the entire system significantly easier to debug, understand and develop against.
- gregoriol 2y agoAnd hack/steal, right?
- vardump 2y ago10 Gb/s is not all that much for cameras. Enough for one 60 Hz 4k 14-bit depth camera transmitting raw bayer data. 60 Hz * 3840 * 2160 * 14bit is 6.96 Gbps.
- dpeckett 2y agoIt's a good thing we invented video compression and hardware codecs/encoders a long time ago. What you'll actually be sending is a high bitrate mpeg stream, probably 54Mbps or thereabouts, you could probably fit 50x camera streams on a shared 10Gbps bus.
- nunez 2y agoFSD will benefit from high-resolution (4K or above) camera feeds (for things like reading signs and detecting small obstacles). You can do this in a 10Gbps network and have tons of headroom for every other function the car will perform.
- aeternum 2y agoBitrate and max devices for CAN are limited.
- cyberax 2y agoCAN is slow. At best it's around 1Mbit, but you get into electrical limitations. So you have to run multiple CAN buses in parallel and carefully manage bandwidth limitations. My Chevy Volt had 4 different CAN buses and one additional LIN bus. This can all be replaced with just two Ethernet buses: for safety-critical and non-critical uses. And the gigabit speed provides plenty of bandwidth for any reasonable sensor traffic, even including camera feeds. The current architecture was justified in 90-s when LIN PHYs were an order of magnitude cheaper than even CAN PHYs. Now Gigabit Ethernet PHYs cost less than a dollar.
- eschneider 2y agoIt's unlikely that the multiple CAN buses are being used to increase speed by, say multiplexing them. In general, vehicles use multiple CAN buses for enhanced security. For example: things like diagnostic ports are often on their own CAN buses so data can't be directly injected into onboard systems.
- cyberax 2y agoAll but one CAN bus in my Volt were connected to the OBD port. The unconnected bus controlled the high-voltage battery contactors and some other critical stuff. The "main" bus was saturated with data, more than 80% of bandwidth utilization at 512kbs. And it kinda had a mix of everything, from street names to be displayed on the dashboard to ECU messages. The other two buses had some random messages, with no rhyme or reason for the split ( https://vehicle-reverse-engineering.fandom.com/wiki/GM_Volt https://vehicle-reverse-engineering.fandom.com/wiki/GM_Volt ).
- throw0101d 2y ago> What is ethernet bringing to the picture? More speed and zonal architecture: * https://www.electronicdesign.com/markets/automotive/article/21248116/molex-harnessing-the-potential-of-zonal-architectures-to-build-next-gen-vehicles https://www.electronicdesign.com/markets/automotive/article/... * https://www.bosch-mobility.com/en/solutions/control-units/zone-ecu/ https://www.bosch-mobility.com/en/solutions/control-units/zo...
- bsder 2y agoLarger packets and bandwidths. Bandwidth: you can't ship backup camera video or entertainment system audio over CAN, for example. CAN was meant for short, real-time packets. 8 bytes in initial configuration. CAN FD allows 64 byte packets. You spend a LOT of protocol doing packet fragmentation and assembly using CAN--which then negates a lot of the real-time guarantees. CAN should be used for the short safety critical stuff. Ethernet should be used for everything else.
- elcritch 2y agoEthernet can handle real time now even in bus configurations! 10BASE-T1S is a new standard geared for automotive. It uses physical layer collision avoidance instead of classic Ethernet exponential backoff. This provides deterministic maximum latency. Though you can get max latency guarantees with switched Ethernet and the appropriate switch QoS and hardware.
- m463 2y agoI'll bet a hidden factor here is development and testing. They can probably develop for a car ethernet lan with a desktop pc and car "peripherals". Not that there aren't canbus cards for pcs, but still.
- numpad0 2y agoThis sounds like the real answer. Replacing an automotive standard with Ethernet is going to reduce friction onboarding junior webdevs with MacBooks, and enable a more stable higher turnover labor intensive organization.
- maxerickson 2y agoCAN to PC adapters are a few hundred dollars, it isn't causing much friction.
- m463 2y agoWith ethernet you can probably run the car software in containers. I can imagine a container to simulate each hardware unit, a small inter-contaner lan, and develop code that way.
- soco 2y agoReminds me when my Opel resetted itself while driving on the highway. Oh, the adrenaline...
- dpeckett 2y agoYou can already do this trivially with Linux vcan[1] so I don't buy this argument. I think the bigger factor is that innovation in the CAN ecosystem has been lagging behind Ethernet for decades now. Only reason it's had such staying power is industry inertia. 1. https://netmodule-linux.readthedocs.io/en/latest/howto/can.html#virtual-can-interface-vcan https://netmodule-linux.readthedocs.io/en/latest/howto/can.h...
- JoshTriplett 2y agoCAN has desirable electrical properties (e.g. hardware-level prioritization) if you have life-critical devices and non-life-critical devices on the same network. But it's painful to deal with from a software point of view, compared to IP-based protocols, for anything that doesn't require the properties of CAN.
- cyberax 2y agoIndustrial Ethernet (PROFINET) also has priorities and bandwidth reservation: https://en.wikipedia.org/wiki/Profinet#Technology_of_Class_C_(CC-C) https://en.wikipedia.org/wiki/Profinet#Technology_of_Class_C...
- throw0101d 2y ago> Tesla really deserves some kudos for pushing the 48V architecture and the Ethernet-based communication. For the record, 42V systems were experimented with in the 1990s: * https://en.wikipedia.org/wiki/42-volt_electrical_system https://en.wikipedia.org/wiki/42-volt_electrical_system In the 2011 German automakers agreed to 48V as the next step after 12V: * https://en.wikipedia.org/wiki/48-volt_electrical_system https://en.wikipedia.org/wiki/48-volt_electrical_system BMW was the first the first with Ethernet: * https://www.marvell.com/blogs/the-right-stuff-a-past-and-future-history-of-automotive-connectivity.html https://www.marvell.com/blogs/the-right-stuff-a-past-and-fut...
- iknowstuff 2y agonone of them actually shipped a mass market almost exclusively 48V product if you’re trying to imply tesla’s push isnt as massive as it is.
- cyberax 2y agoThis has been a real head-scratcher for me. BMW and other automakers could have vastly improved their cars by switching to 48V a decade ago, but they still keep just plodding along with 12V. I have no explanation for this.
- hulitu 2y ago> automakers could have vastly improved their cars by switching to 48V a decade ago, The microcontroller still runs at 5/3.3/1.8 V.
- theshrike79 2y agoTradition, long supply chains etc. Tooling all their shit to 48V is a massive undertaking with pretty much zero advantages.
- cyberax 2y agoThey don't need to retool all the factories at once. They could have gradually introduced 48V systems in parallel with 12V, slowly phasing in new components as they replaced the old 12V.
- Muskyinhere 2y ago[dead]
- saturn8601 2y agoYou'll be sorry when this move further hamper repair efforts and the TCO of owning a vehicle goes up.
- porphyra 2y agoYou can say that about any new standard. With that logic we'd all be stuck with knob and tube wiring.
- ElevenLathe 2y agoDid cars ever use knob and tube?
- jeffbee 2y agoHow about comparing it to a teardown of a Rivian? Rivian uses 2-wire ethernet but 12V, so it seems like a more interesting comparison. That said, it all seems like inside baseball to me. The BMW 850i pioneered the CAN bus, but that car was forgettable and although CAN bus took over the car industry that did not seem to create any durable advantages for BMW. Ethernet seems like the inevitable replacement for CAN, in light of VW's investment in Rivian, and 48V vs. 12V for the low-voltage systems seems like a wash.
- hulitu 2y ago> Tesla really deserves some kudos for pushing the 48V architecture and the Ethernet-based communication. And some schooling. They shall learn about pokayoke.