Hello, all

Recently,we  debug a board.There is a MPC850 chip on our board.The
type of our MPC850 chip that we use is XPC850SRZT50BU.Now we meet a
problem about MPC850 reboot.Below is the details:


1.We use vxWorks as our operation system.Sometimes we need use the
function 'reboot' to reboot the MPC850 chip.When we reboot  about 10
times,we found that the MPC850 chip is still in reset state.The
HRESET
signal is still asserted and the CLKOUT signal is not correctly
locked,so the MPC850 cannot work continue.


2.There is a watch dog chip on our board.Sometimes we need use watch
dog chip to reset our MPC850.The watch dog chip will assert MPC850's
POREST signal when it isn't fed within 1.6 second.The result is very
similar.When we reboot about 10 times,we found that the MPC850 is
still in reset state.But in this situation,the HRESET signal is
negated,the CLKOUT signal is not correctly locked.


In both two cases above,if manully reset the board,then everything is
OK.


Could you tell me where is the problem ?


thank you very much


leo

Since you do not see a clock on CLKOUT, you are not correctly locking
the PLL's and getting out of HRESET. I'd guess that you're not reading
in the reset config word properly - you need to have pull-ups and pull-
downs on the whole bus for the reset word. Do not rely on the weak
internal pull-ups, they are not reliable.

I would look at that first - also make sure the clock-in is stable,
and the PLL filter is correct.

 ... Paul


On Jul 24, 9:34=A0pm, wylg <wyl...@sohu.com> wrote:
> Hello, all
>
> Recently,we =A0debug a board.There is a MPC850 chip on our board.The
> type of our MPC850 chip that we use is XPC850SRZT50BU.Now we meet a
> problem about MPC850 reboot.Below is the details:
>
> 1.We use vxWorks as our operation system.Sometimes we need use the
> function 'reboot' to reboot the MPC850 chip.When we reboot =A0about 10
> times,we found that the MPC850 chip is still in reset state.The
> HRESET
> signal is still asserted and the CLKOUT signal is not correctly
> locked,so the MPC850 cannot work continue.
>
> 2.There is a watch dog chip on our board.Sometimes we need use watch
> dog chip to reset our MPC850.The watch dog chip will assert MPC850's
> POREST signal when it isn't fed within 1.6 second.The result is very
> similar.When we reboot about 10 times,we found that the MPC850 is
> still in reset state.But in this situation,the HRESET signal is
> negated,the CLKOUT signal is not correctly locked.
>
> In both two cases above,if manully reset the board,then everything is
> OK.
>
> Could you tell me where is the problem ?
>
> thank you very much
>
> leo