[hpsdr] Demeter = HPSDR power supply(?)

[Thomas McLaughlin]

Roger, Chris, all,

The ATX power supply spec provides for remote
actuation
of the power supply through pin 14 (usually green) of
the Molex Mini-Fit, Jr. connector (aka ATX connector).
The power supply is supposed to maintain 3.3 or 5V on
that pin. Grounding pin 14, signals the power supply
to
turn on.  Likewise, letting pin 14 float (above 0.8V)
signals the power supply to turn off.  "Upgrading
and Repairing PCs" by Scott Mueller is a pretty good
reference.  Similar info and specs are available
online.

DIY linear power supplies should be designed to
conform
to the same specs.

The ATLAS board does have the external power switch
functionality. According to the docs, connecting T7 to
T8 will activate the power supply.  Since T7 connects
to the ATX connector pin 14, this makes sense.  By
installing header pins in T7 & T8, a jumper can be
used
for always on, or a conventional DPST non momentary 
switch can be used for panel switching.

To do bus controlled (or momentary switch) power
activation is a little more complicated, but doable.

The method of interest to me is using the 1-Wire bus
(A18 on ATLAS) to control a Dallas/Maxim DS-2405
1-Wire
addressable switch.
http://www.maxim-ic.com/quick_view2.cfm/qv_pk/2906
The remaining question is the bus master for the
1-Wire
network.  Any suggestions?

Thomas KG6ZOO

--- Chris Albertson <chrisalbertson90278 at yahoo.com>
wrote:

> >
> >If the PS is to have the ability to be shut down on
> command then
> >somehow Ozy and Sasquatch need a way to communicate
> with the PS
> >either by setting a voltage on a line or by sending
> a
> >command over a serial interface.  The ability of
> the PS to send
> >status information such as voltages and current
> implies the
> >serial interface.  On a backplane-centric system
> >it seems natural to use the backplane for
> communications.


--- Roger Hayter <roger at hayter.org> replied:

> There's a pin on the Molex connector specifically
> for providing standby 
> 5V power, and another for switching the ATX psu on
> and off - I keep 
> meaning to check if these  pins is available on the
> ATLAS board, the 
> latter pin must be connected to something to switch
> the PSU on.



       
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