Microcontroller basics - where to start

[ThermallyFrigid]

Hello,

I am seeking advice on a path to learn more about microcontrollers.
My goal would be to duplicate them.
Specifically, I am interested in automotive microcontrollers from older vehicles (25 years old approximately)
These microcontrollers are used on various control boards throughout the vehicle such as on HVAC control boards, Body Control Modules, Transmission control modules and the like.
As the vehicles get older the chances of the microcontrollers failing becomes greater and I want to keep them running indefinitely.

What tools would I need in order to read the data (if accessible?)

I am also interested in learning assembly language or whatever is necessary to learn to create replacement microcontrollers from scratch if necessary.
Obviously, this is a pretty tall order and I'm not even sure this is possible.  Maybe like wanting to create atomic fusion, with no physics knowledge?

Can you offer any suggestions?  Below is a photo of one specific microcontroller I would like to duplicate.  it is from a 2005 Dodge Grand Caravan.
Than you

[ejeffrey]

You can't practically "replicate" a microcontroller in any significant sense.

The best you can usually do is to find a replacement.  Automotive microcontroller have long life cycles and even if they are out of production you may be able to find old stock.

The tricky part is programming them.  You need to get the firmware.  Most automotive micros will have security measures to prevent users from pulling the firmware. Often those security measures are broken but it takes a fair bit of research to learn how to bypass it for a specific part.

I'm not sure it's true that microcontrollers often fail.  Digital control modules are a know failure point but there are lots of ways they can fail besides the MCU itself giving out.  The regulators, solenoid controllers, sensors, and IO drivers are all probably more exposed to the external world and more likely to fail.  Also vibration and heat are as likely to affect the the PCB, mechanical assembly, or capacitors as much as the MCU.  Replacing an MCU on a broken PCB may result in just frying the new MCU!

[bingo600]

My guess would be Freescale (Old Motorola)
https://en.wikipedia.org/wiki/Freescale_Semiconductor

A lot of this automotive stuff is mask programmed and wo. any public info.

Might not be an easy task 

[SteveThackery]

Basically I think you've got no real chance of replicating any of the ECUs you will find in a car. They are highly complex, often protected against reading or hacking, and you'll need to work out the CAN bus protocols used by the manufacturer to talk to it from the OBD2 port or similar.

You can buy general purpose engine management ECUs such as the MicroSquirt and MegaSquirt, but they need you to program them with the engine maps. If there isn't a map available in the community you'll need a rolling road dynamometer and a lot of expertise.

It might be easier to build a general purpose car ECU (perhaps you can buy them) and program it to operate the relevant part of the car without regard for the system-wide integration, but I can imagine error codes and lights on the dashboard.

Honestly, I don't think it is realistic.

[WattsThat]

As others have already pointed out… attempting to duplicate or recreate a ECU with a different microcontroller is not a realistic goal. The programs in the ECU’s are pretty well locked out of sight using various methods. Yes, given enough time and money, they could be reverse engineered but that’s not something you can do easily, I’d estimate about 10 plus years of experience and a $100,000 worth of equipment to get a controller to give up its secrets.

The best you can achieve is to gain enough understanding of how microcontrollers work and how they interface to the external devices they control. This will aid greatly with troubleshooting and repair of existing ECU’s.

Oh, a good starting point: a proper Arduino starter kit with modules. Something like this:

https://www.amazon.com/Arduino-Starter-Kit-English-Official/dp/B009UKZV0A/ref=sr_1_1_sspa

[ThermallyFrigid]

I have been successful at backing up the flash code and saving it, then flashing it into another chip.
Once I have the code extracted from the chip it would be a matter of decompiling the code.

I'm wondering if the "No Can Do" comments are related to encrypted code, which may not be the case in the older vehicles I'm working on.
In fact, I can already say it is not encrypted since I can load the Hex code into a Hex editor and see the instructions.   I just have not been able to decomplie the code yet.

Or, I am so lost I have absolutely no clue what I'm saying.

[Lindley]

That sounds a very tall order as well as the micro chip you will probably have to redesign the rest of the hardware as some of the smaller components may well be obsolete.

You do not mention what autos you are working on, but our first thoughts would be to look around to see if anyone has already done something like that  ?

We would also make contact with a company that repairs such boards as they will have a wealth of info available and they might be willing to assist ?

Though you can decompile code, working out what that code is doing can be very difficult.

[Dazed_N_Confused]

Can you offer any suggestions? 
(Attachment Link)

 C is the language you will want to learn.
I money says you have many many more solder joint problems on the board, than micro problems.

[Doctorandus_P]

My advise is to forget about these automotive things for a while. Just get a few generic microcontroller development boards, and start with blinking LED projects on a breadboard. Breakout boards that fit in a breadboard are a good choice for a beginner (For example Arduino nano, Raspi pico).

Once you have a good understanding of the basic principles of working with microcontrollers you can go back to attempt your automotive endeavor. But it's not a good place to start.

[rteodor]

I'm wondering if the "No Can Do" comments are related to encrypted code, which may not be the case in the older vehicles I'm working on.
In fact, I can already say it is not encrypted since I can load the Hex code into a Hex editor and see the instructions.   I just have not been able to decomplie the code yet.

Or, I am so lost I have absolutely no clue what I'm saying.

Its not that hard to do it ... once you get a bit of experience. But those initial steps until you get proper knowledge are indeed very hard.
In fact you kind of know what the software does, you only need to find out how its doing it. And there are patterns of how things are done in software. That is why is a good idea to work a bit with something like an Arduino or Pico and real-time operating systems and programming if you say you are starting from scratch. But you don't need to stay with them for long. The purpose would be to be able to handle something like Ghidra with ease.

There are specific patterns in the automotive, and then there are even more specifics to module itself and to the developers that made them. You will start to recognize them once you do enough of them.

Congratulations for persisting.

LE: Working with these older MCU's has the advantage that with time their protections mechanisms are revealed ... to those brave enough to go on the dark streets with no lighting. But don't ask me, I'm not one of them.