PIC16F628A

[hogar]

Does anyone know how to extract the program from ??

[zawmintun1]

Search in google as PIC Disassembler

[Magnox]

Connect a programmer to it and select the option to read the target's memory. That will get you the hex file which can be opened in a disassembler.

That's assuming the code protection is not enabled.

What are you trying to do exactly?

[hogar]

I try to "borrow" idea of
device for monitoring
seed corn in the pneumatic planter...
which
programmer would be the best for this attempt???

[Sideshow Bob]

This will not work if the chip has code protection on Which I think is most likely. But is does not hurt to try. A PICKIT 2 or 3 should do the job for you

[kayvee]

Even the older Picstart Plus would work just fine.

As Bob said above, code protection will be set on most all commercial projects, but then you never know...

If set, it is probably easier to write the code yourself from scratch.

[ZASto]

Best for "borrowing" someone else's ideas: http://www.break-ic.com
When you get the "code" than you can disassemble it

[alfonsoagama]

I try to "borrow" idea of
device for monitoring
seed corn in the pneumatic planter...
which
programmer would be the best for this attempt???

You need to do is reverse Engineering.
Try to do with a USB logic analyzer.
It's very simple.
1.- Identify Inputs and Outputs
2.- Read them with the logic analyzer
3.- Interpret Output conditions.
4.- Program the source code for a new chip like PIC16F628A or another similar that behaves as the original and simulate it on Proteus.
5.- Make a Prototype PCB
6.- Probe it.
Good Luck

[dotm]

just for information, there are some ways to extract the flash from a pic mcu with blown fuses.

"Another  example  is  an  old  PIC16F84 microcontroller  from Microchip  [91].  The  chip  erase
operation removes  the security protection but at  the same  time erases  the contents of program
and data memories on the chip. The hardware design of the security protection circuit is made
such  that  the memory  is  always  erased  before  the  security  fuse  is  reset  to  the  initial  state.
However  it  was  found  that  if  during  the  chip  erase  operation  the  power  supply  voltage  is
increased to about 10 V for a few milliseconds it causes the memory erase process to terminate
but  the  security  fuse  reset  finishes  as  usual  making  it  possible  to  read  the  contents  of  the
memory. Such a high voltage pulse  should be applied carefully as  increasing  its  length could
permanently damage  the chip. The  later revision of  this microcontroller, PIC16F84A [92], has
protection  against  under-  and  over-voltage  attacks.  Any  memory  modification  operations
performed  via  the  programming  interface  are  immediately  terminated  if  the  power  supply
voltage goes below 3 V or above 6 V.   62
It  is  not  always  necessary  for  the  power  glitches  to  be  outside  the  specified  power  supply
voltage range. For example, in the same PIC16F84A microcontroller the protection mechanism
can be defeated by applying a mere 50 mV glitch after the chip erase operation has started. That
causes termination of the program memory erase operation but not the fuse erase. "

from
http://www.cl.cam.ac.uk/techreports/UCAM-CL-TR-630.pdf

also look here:
http://www.cl.cam.ac.uk/~sps32/mcu_lock.html