[time-nuts] An embedded NTP server
Jim Lux
jimlux at earthlink.net
Tue Jan 1 21:58:34 UTC 2013
On 1/1/13 12:16 PM, Poul-Henning Kamp wrote:
> --------
> In message <AA21D17C-0FF4-4B22-B3A3-43AC2B9DAA58 at rtty.us>, Bob Camp writes:
>
>> I'm not bashing the Arm parts, [...] They worry about every uA of
>> current drain
>
> True story:
>
> Many years ago when the very first ARM silicon arrived and they started
> testing it, it was generally execeeding expectations but a little bit
> flakey at high clock rates.
>
> After the bubbly had been drunk and hangovers subdued, the serious testing
> started and one of the first thing they found was that they had forgotten
> to hook up VCC: The chip ran entirely on leaked power from the I/O pins,
> most notably the #RESET pin.
>
> When they also connected the VCC pin, it was stable well above spec'ed
> speed.
>
more than one person (including me) has found out that with boards
powered from their I/O interfaces rather than the power supply that they
forgot to turn on.
It's a huge deal in the spacecraft world because of the desire to do
cross strapped redundancy with cold spares. Is the interface truly
"dead faced"? And if you have a pyro actuated cable cutter, what
happens if power from one wire couples into an interface for an
unpowered unit?
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