RE: Re: Raspberry Pi in HA?

["Dave McLaughlin" <dave_mclaughlin@xxxxxxxxxxxxx>]

Hi Stuart,

PCB's look like done with Eagle.

Without seeing the schematic I can't confirm what's on the PCB in detail
but
I don't see any decoupling capacitors on any of your 2 boards you show.

Earlier in my PCB design myself and later my friend used to build PCB's
without any these and always wondered why they would sometimes stop working
or be troublesome.

You ideally want at least 100nF at each device and/or at each VCC supply
pin
for each IC. The closer to the device the better. I also include a minimum
of 4u7F cap at the power input for each board.


Sorry if you already have these but just an observation of the current
layouts you posted.

Cheers.
Dave...

-----Original Message-----
From: ukha_d@xxxxxxx [mailto:ukha_d@xxxxxxx] On Behalf Of
Stuart Poulton
Sent: 20 May 2012 20:34
To: ukha_d@xxxxxxx
Subject: Re: [ukha_d] Re: Raspberry Pi in HA?

Simon,

The key is the use of the DS2482-800, this provides 8 1-wire busses, so no
need for a hub.
As you correctly point out there are some power restrictions with the Pi.

I've done some initial designs for breakout boards

http://raspberrypi.homelabs.org.uk/raspberrypi-1-wire-expansion/

I'm willing to take suggestions and ideas though.
I'm also looking at i2c i/o options for example i2c relay modules.

Stuart






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