Anything connected to a BBB must not be powered up until the BBB is
powered up so what you have done is correct


On 6/14/2016 10:06 AM, [email protected] wrote:
> Just a "me too" reply, echoing Ralf's comment.
>
> On my board, the Beaglebone is a "guest". The host board runs off +24
> V, and provides two SMPS (5V and 3V3) to subsystems. The host 5V is
> hooked up to the BBB barrel jack pins on P9. The BBB's 3V3 supply is
> left unconnected, and the host board supplies 3V3 to various systems.
>
> Without sequencing the host 3V3 to SYS_RESETn, I was getting
> approximately 80% failure rate for the PHY, even with
> bone-debian-8.4-lxqt-4gb-armhf-2016-05-13-4gb.img. (This was manually
> recorded with ~20 attempts.)
>
> When I keyed the 3V3 SMPS off SYS_RESETn, the PHY behaved much better,
> 10/10 times.
>
> Hoping this can help someone else!
>
>  - Tim
>
> On Sunday, April 3, 2016 at 7:59:49 PM UTC-4,
> [email protected] wrote:
>
>     Hi all,
>
>     The problem seems to be influenced by the outside power supply.
>
>     I run Debian Jessie with kernel 4.1.15-ti-rt-r43 on an 1month old
>     element14 BBB (where do I find the revision??) and have the same
>     issues.
>     The BBB is getting its power from a custom carrier board which has
>     a DC-DC on. Doing a cold start by plugging the battery in, the
>     Ethernet is hit and miss (more miss than hit).
>     Pressing the reset button got it working every time so far.
>
>     The DC-DC isn't running perfect yet, as it only got the
>     theoretical values in and is not optimized yet.
>
>     Regards
>
>     Ralf
>      
>
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