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why the fuck is DMA enabled on a diagnostics port

Well you have to ask for it, read-only. It's a firmware feature. Its called Data Memory Read I believe, DMR was the acronym. You can ask the processor to fetch values from running memory once or twice per second. I think most CAN systems will only allow 4 DMR per second but I could be outdated on that.

Only the processor can write to memory and in my experience there are no routines to write to RAM. There are routines to overwrite ROM in special conditions, flashing obviously. We sold devices that attached to the bus directly which had the ability to do whatever you wanted :)

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Discussion

semisol 4mo ago

The deeper I look into automotive it feels like piles and piles of bloat that no one understands

ChipTuner 4mo ago

Welcome to automotive! How can we piss you off today?

semisol 4mo ago

The existence of it is enough.

I became aware of the automotive hellhole primarily because the SE company I work with is primarily focused on automotive and industrial systems. They do have a bunch of automotive focused SE's of course, I think some of their demos included measuring passenger motion with UWB (what's the benefit?!), their low-latency end-to-end encryption stuff, and I don't remember the rest.

ChipTuner 4mo ago

Tell me if it feels like they couldn't seem to care any less about consumer rights like this, Im not judging, the motivation just isn't there. I assume there is a high focus on convenience, but the red-tape surrounding repair and consumer education/information is just an expense no one wants to deal with.

semisol 4mo ago

They make semiconductors and therefore couldn't care if it happened or not

ChipTuner 4mo ago

Ah.

ChipTuner 4mo ago

But still yeah, when I ask for 01000h it reads me whatever was stored in the register address 01000h. On my roms, this address is usually start of the SRAM register file for the static data segment. Anything above that address is reserved or used for cpu working memory although there isn't much of that. Generally there is enough register file to use every register for a dedicated purpose XD