RE: Oscilator Boot problem

William,

This sounds like the 400 is booting normally but the quiet boot pin (P1.7)
is stuck low and the net boot pin (P5.3) is high.  This tells the ROM to go
and look for user code instead of attempting to auto baud for serial loader
mode or attempt to net boot.  If the ROM cannot find any user code in the
memory and the net boot pin is not active the ROM puts the 400 into stop
mode since there is no way for new code to appear.  While in stop mode the
crystal driver is shut down to save power.

This behavior is explained on page 69 of the DS80C400 Network
Microcontroller Datasheet.  Figure 12 on page 70 shows the flowchart that
describes the ROM Code Boot Sequence.

Hope this helps.

Jeremy

> -----Original Message-----
> From: tini-admin-6tN4nzCoH/[email protected] [mailto:[email protected]]On Behalf Of
> william
> Sent: Tuesday, February 10, 2004 7:23 PM
> To: tini-6tN4nzCoH/[email protected]
> Subject: [TINI]Oscilator Boot problem
>
>
> Hello,
>
> We developed a custom board based in the reference design.
>
> We have this problem: when we power-on the board the oscillator of the
> cpu starts to work, but it stops after 200 ms aprox. We tried different
> crystals, with differents values of capacitors, without any result.
>
> Any idea?
>
> Thanks,
>
> William
> w99 at terra dot com dot br
> Sao Paulo -SP
> Brazil
>
>
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