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the cybergibbons @cybergibbons
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Many automotive microcontrollers don't have public datasheets.

This could be termed security-through-obscurity, but if you need to reverse engineer a complex processor in LBGA256 on an 8-layer board that you only have one of, that datasheet is going to be very helpful.
I'll discuss a specific device - the ST SPC56EC80 in TQFP64. It's in a device I have looked at in the past.

There is a "data brief" available. It doesn't have that much useful, it is for marketing:
st.com/content/ccc/re…
So, first thing is to ask for them:
community.st.com/thread/39097-d…

(I didn't say "Most urgently" - they oddly edit the posts)
The response:
"i will forward your request to the Marketing guys."

This is code for "you aren't getting them"
Other people ask, and get directed to the wrong place:
community.st.com/thread/40939-i…
Next thing - try downloading the IDE - SPC5-STUDIO. The IDE for many processors is free (but sometimes limited).

SPC5-STUDIO has a "pin wizard" letting you see the pinouts.
Even if it doesn't have pinouts, the HAL/BSP will provide a lot of clue to what pins do. The IDE doesn't have support for it.

Back to the forums.
community.st.com/thread/39099-s…

"if the marketing guys are ok"

Well, they never replied to me so I guess they weren't.
It's quite common for processors in the same line and package to share pin-out.

st.com/content/ccc/re…
Unfortunately, there are no datasheets for them either.

What's the next thing to look at? Development boards.
They are still a bit cagey. But we find a PDF:
st.com/content/ccc/re…
The board on the right is interesting - it is TQFP64 like the chip we are looking at.

A SPC582B-DIS.
Find the page for this...

st.com/en/evaluation-…
And now we have the layout and schematic of the dev board. From this, we can see which pins are JTAG quickly. It's not 100%, but we can be fairly sure.
Oddly, there is an error in the manual. It says TDI is 38 - it's 39.
So rather than JTAGulate 32 odd pins on the device, we know which pins they are.
One other trick - IDEs often download support for given processors on-the-fly. Intercept the comms, try a bit of forced browsing or hope for open directory listings...
Hope that gives some ideas for how to find things!
Typo SPC58EC80.
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