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Home > The Amp Hour Electronics Podcast > #634 – The CAN bus can! with Dr Ken Tindell


	Podcast:		The Amp Hour Electronics Podcast
	Episode:		#634 – The CAN bus can! with Dr Ken Tindell
	Category:		Science & Medicine
	Duration:		01:08:47
	Publish Date:		2023-05-30 23:16:08
	Description:		Welcome Dr Ken Tindell of Canis Labs Ken heard episode #631 where Chris was talking about a Noisy Rude Bus and he objected. Stringently (it seems Ken has since pulled down the posts, but they were in good fun) Chris had been planning to talk about Ken’s recent awesome post about CAN hacking and cars being stolen, so he asked Ken to be on the show! CAN was invented to reduce weight in car cable harnesses, which were increasing rapidly with more electrical features being included. CAN vs LIN CAN was expensive, but LIN is cheap because it’s bit banging the protocol from a microcontroller There are bridges to go between CAN and LIN buses. Modern cars have 20-100 ECUs (controllers), but it depends on the features the car has. But that’s not just microcontrollers, Ken estimates that could be as high as 700. Chris and Ken both had dealth with Philips / Freescale / NXP / Motorola as silicon vendors in the automotive space How does a tiny microcontroller get data onto the bus? Prioritized traffic CAN indentifier field has priority baked in Bus works like a giant AND gate where the lowest address wins 11 bits How to unwind CAN traffic Packing signals into CAN frame Tools to reverse engineer Protocol decoder for sigrok CAN HG 250kb is slow CAN bus bandwidth There is Ethernet in cars now, especially with more and more cameras Bandwidth vs latency Addressing through a gateway Atomic broadcasts means you know that each device has processed it Protocol hacking Trucks aren’t OEM based so more vertically integrated SAE J1939 standard in trucks If say Toyota develops the CAN messages, DBC files decode everything. But manufacturers don’t publish them, so some car messages are reverse engineered Accessories bus Who has access to DBCs? Diagnostic systems OBD2 CARB CAN is physical ISO 11898 CAN XL has IP packets, so you can use wireshark Ken has written about wireshark CAN 2.0, CAN FD Devices on a bus are normally all bare metal or RTOS because of the timing requirements OSEK standard Embedded system abstraction Dealing with the magnitude of decisions making in the automotive industry Chris asked about whether self-driving will happen in 5 or 20 years? (ie. does he agree with Chris or Dave). It was the latter, sadly. Autonomic Cars podcast with Dr Phil Coopman
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