Electronics > Microcontrollers

Reusing / repurposing MCU's on PCB's ?

(1/2) > >>

MathWizard:
For example, I have a nice 16-bit MCU, that uses C-languange, it's on a TV PCB, with RAM/ROM chips, and lot's of easy places to connect to the MCU traces, once the other chips and passive's are removed.

For a typical commercial product MCU, is it hard to erase the internal ROM/RAM on MCU's ? Are they sometimes fused off so you can't erase/reprogram them ? Or maybe you need a special machine just for a certain chip ? Or maybe only top level hackers and programmers can do this, and no one else bothers ??

I'm just wondering for down the road when I get way more into MCU's. Since it's already on a PCB, with lot's of traces and RAM. If the MCU can't be reprogrammed, I think I could get a new, blank one, and at least reuse the PCB.

Fire Doger:
is it hard to erase the internal ROM/RAM on MCU's ?
Depends on the MCU.

Are they sometimes fused off so you can't erase/reprogram them ?
Yes

Or maybe you need a special machine just for a certain chip ?
Each mcu family has their own programming tools.

Or maybe only top level hackers and programmers can do this, and no one else bothers ??
You are not hacking anything, you are recycling the chip.
There is a huge market in china with reused parts.

You can just buy a development board to learn, no-one uses products as dev boards, the amount of time to reverse engineer it doesn't worth it.

DavidAlfa:
Does it make any sense when you can get a small mcu board with a well known architecture for $4 at aliexpress?

Andy Chee:
I once repurposed a salvaged 68HC711E9 OTPROM, by running it in expanded multiplexed mode, essentially becoming an HC11E0 (which uses external ROM).  I've also salvaged the odd PIC18F and Atmels/Attiny.  These can be erased even with the security bit set (which only prevents dumping the code, not chip erasure).

So yes it's possible to repurpose MCUs for experimenting with.  Is it worth it?  There's zero monetary value in doing so (unless you're a massive Chinese e-waste recycler), so the only value is personal knowledge and skills gained.

Doctorandus_P:
It is not very common for microcontrollers to be completely locked. Most have some safety features that prevents the code in them from being read out, but almost always you can do a full erase that both erases the code and resets those features.

There is a lot of very cheap equipment from Ebay / Ali / China that uses STM32 (or clones). For example the Gophert power supplies, ESC speed controllers, FX2N PLC boards, Electronic loads, power supply modules, solder iron controllers and many more, and the microcontrollers on these boards usually just need two wires (+ GND) to erase them and reprogram them.

But when it comes to some random 16-bit microcontroller on some random consumer electronics board, then it's just not worth the effort. Setting up a toolchain, sourcing a programmer, learning how the peripherals of a uC family work all take a lot of time. It may even be very difficult to get datasheets for microcontrollers used in high volume consumer electronics. And when you can get it to work... What if you have spend 200 hours getting it to work and writing a program for the thing, and then you want to get another and you can't buy the part? There are literally thousands of microcontrollers you can buy for less than EUR2. The smaller ones start somewhere between 30ct and 50ct, and you can also buy lot's of them on breadboard friendly breakout boards.

Navigation

[0] Message Index

[#] Next page