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About the basic set up

Started by korchis April 25, 2006
hello im a student working on my senior project. we have selected the hcs12
as our MCU for this project. however, things are not as easy when you are
asked to actually surface mout and connect the hcs12. we have 3 hcs12s
(but naked) -the 112 pin chip alone. is there a way someone can help my by
providing my with the most basic hardware set up schematic?. we have built
about 3 pc boards and none had worked. the freescale site is not much
helpful. we are sure we have built a proper clock, a proper reset button,
a proper sci interface (used max233), proper jumpers for moda, modb, and
modc pins. but for some reason it just dosent work. is not like im asking
for it to respond with any d-bug 12. i just need the basic bootloader.
another thing, does any one know if this family has already the bootloader
from factory. if not i heard that in order to load the s-record containing
the bootloader one has to make use of other pins. which pins?, and how to
interface with them? 

   any help will be much welcomed.....thank you....


korchis wrote:
> hello im a student working on my senior project. we have selected the hcs12 > as our MCU for this project. however, things are not as easy when you are > asked to actually surface mout and connect the hcs12. we have 3 hcs12s > (but naked) -the 112 pin chip alone. is there a way someone can help my by > providing my with the most basic hardware set up schematic?. we have built > about 3 pc boards and none had worked. the freescale site is not much > helpful. we are sure we have built a proper clock, a proper reset button, > a proper sci interface (used max233), proper jumpers for moda, modb, and > modc pins. but for some reason it just dosent work. is not like im asking > for it to respond with any d-bug 12. i just need the basic bootloader. > another thing, does any one know if this family has already the bootloader > from factory. if not i heard that in order to load the s-record containing > the bootloader one has to make use of other pins. which pins?, and how to > interface with them? > > any help will be much welcomed.....thank you....
Start by trying to find a known, working, reference design and compare your schematic to it. It is possible that there is something that you missed or are unware of that is critical to the operation. Double check items such as voltage and ground at all of the proper pins, clock within specification, proper use of decoupling capacitors, proper voltage for power and all grounds present, length of reset pulse, etc. Second, it sounds as though your assembly practices may be in question as I am getting the impression that the board(s) was constructed possibly by inexperienced hands without the proper tools. If this is the case, consider having the board built by a company that manufacturers it. Third, try to refine the concept of not working and consider that you may be attempting to bite off too much at once. Are you able to get the device to talk to the emulator or debugger? Are you able to get any activity at all? If not, I would go back to the first and second suggestions and double check the design and make sure the assembly is correct. Is it possible the parts were damaged by mishandling or some other issue? Are you certain that the PCB is good? One final suggestion, build the board up in stages. Start with the power and ground circuitry and make sure that you don't have any shorts and that you are getting the proper voltage at all of the correct places. Once you are certain that you don't have a problem that will destroy the rest of the components when you build the board, then proceed with building the rest of it up.