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.
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
> 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
> Could you tell me where is the problem ?
> thank you very much