[9fans] RaspberryPi, monitor energy saving

[9fans] RaspberryPi, monitor energy saving

[Steve Simon]

Its just wonderful to have a raspberry pi as a plan9 terminal,
but the energy saving of the pi is outweighed by the monitor I use.

The Pi's display code blanks the screen after a while but this does
not shutdown the monitor.

I dug a little and it seems I need to send CEC (Consumer Electronics Control)
messages over HDMI - Via a Pi GPU entrypoint.


Porting libcec looks a little painful especially as I only need to be able
to send two messages (turn on and turn off).

Anyone know anything about this stuff? is CEC what I need or is there some
other (simpler) way?

-Steve

Re: [9fans] RaspberryPi, monitor energy saving

[Bakul Shah]

On Thu, 15 May 2014 22:04:34 BST "Steve Simon" <steve@quintile.net> wrote:
> Its just wonderful to have a raspberry pi as a plan9 terminal,
> but the energy saving of the pi is outweighed by the monitor I use.
>
> The Pi's display code blanks the screen after a while but this does
> not shutdown the monitor.
>
> I dug a little and it seems I need to send CEC (Consumer Electronics Control)
> messages over HDMI - Via a Pi GPU entrypoint.
>
>
> Porting libcec looks a little painful especially as I only need to be able
> to send two messages (turn on and turn off).
>
> Anyone know anything about this stuff? is CEC what I need or is there some
> other (simpler) way?

May be use a gpio pin to control a switch?!

Re: [9fans] RaspberryPi, monitor energy saving

[Shane Morris]

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This might be wildly off the mark, but is there something VESA related to
do this, VGA monitors, et al?

I prepare to stand flamed. ^.^


On Fri, May 16, 2014 at 8:26 AM, Bakul Shah <bakul@bitblocks.com> wrote:

> On Thu, 15 May 2014 22:04:34 BST "Steve Simon" <steve@quintile.net> wrote:
> > Its just wonderful to have a raspberry pi as a plan9 terminal,
> > but the energy saving of the pi is outweighed by the monitor I use.
> >
> > The Pi's display code blanks the screen after a while but this does
> > not shutdown the monitor.
> >
> > I dug a little and it seems I need to send CEC (Consumer Electronics
> Control)
> > messages over HDMI - Via a Pi GPU entrypoint.
> >
> >
> > Porting libcec looks a little painful especially as I only need to be
> able
> > to send two messages (turn on and turn off).
> >
> > Anyone know anything about this stuff? is CEC what I need or is there
> some
> > other (simpler) way?
>
> May be use a gpio pin to control a switch?!
>
>

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Re: [9fans] RaspberryPi, monitor energy saving

[Steve Simon]

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i believe that this works for vga attached monitors, vesa says that when the clocks
disappear on the sync the monitor should shutdown.

the raspberry pi uses hdmi and also it doesn't use a vesa bios, it has a gpu bios
which does a similar job but is not standardised, and, though it is documented,
it can be tough to use (for me at least).

i am happy to be contradicted on any of this of couse.

-Steve




> On 16 May 2014, at 04:53, Shane Morris <edgecomberts@gmail.com> wrote:
> 
> This might be wildly off the mark, but is there something VESA related to do this, VGA monitors, et al?
> 
> I prepare to stand flamed. ^.^
> 
> 
>> On Fri, May 16, 2014 at 8:26 AM, Bakul Shah <bakul@bitblocks.com> wrote:
>> On Thu, 15 May 2014 22:04:34 BST "Steve Simon" <steve@quintile.net> wrote:
>> > Its just wonderful to have a raspberry pi as a plan9 terminal,
>> > but the energy saving of the pi is outweighed by the monitor I use.
>> >
>> > The Pi's display code blanks the screen after a while but this does
>> > not shutdown the monitor.
>> >
>> > I dug a little and it seems I need to send CEC (Consumer Electronics Control)
>> > messages over HDMI - Via a Pi GPU entrypoint.
>> >
>> >
>> > Porting libcec looks a little painful especially as I only need to be able
>> > to send two messages (turn on and turn off).
>> >
>> > Anyone know anything about this stuff? is CEC what I need or is there some
>> > other (simpler) way?
>> 
>> May be use a gpio pin to control a switch?!
> 

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Re: [9fans] RaspberryPi, monitor energy saving

[Shane Morris]

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Yeah, I was kind of the mentality of "Well, if its HDMi, its basically
single link DVI..." Of course, it is its own standard, CEC is probably the
simplest way of achieving this, there is a CEC-serial bridge, various
websites have them. I've looked into them before, before I started using
all Macs because of my job. The old Pi sees little use these days =(

The thing with the CEC-serial bridge is, do I spend $*x* on this device, to
save $*y *worth of power over *z* period of time, and at the end of the
day, am I making an acceptable ROI? YMMV. I just had this same debate with
a bloke from the Czech Republic about the Australian Government incentive
scheme for household solar panels, and no energy storage facilities. Again,
YMMV.


On Fri, May 16, 2014 at 6:45 PM, Steve Simon <steve@quintile.net> wrote:

> i believe that this works for vga attached monitors, vesa says that when
> the clocks
> disappear on the sync the monitor should shutdown.
>
> the raspberry pi uses hdmi and also it doesn't use a vesa bios, it has a
> gpu bios
> which does a similar job but is not standardised, and, though it is
> documented,
> it can be tough to use (for me at least).
>
> i am happy to be contradicted on any of this of couse.
>
> -Steve
>
>
>
>
> On 16 May 2014, at 04:53, Shane Morris <edgecomberts@gmail.com> wrote:
>
> This might be wildly off the mark, but is there something VESA related to
> do this, VGA monitors, et al?
>
> I prepare to stand flamed. ^.^
>
>
> On Fri, May 16, 2014 at 8:26 AM, Bakul Shah <bakul@bitblocks.com> wrote:
>
>> On Thu, 15 May 2014 22:04:34 BST "Steve Simon" <steve@quintile.net>
>> wrote:
>> > Its just wonderful to have a raspberry pi as a plan9 terminal,
>> > but the energy saving of the pi is outweighed by the monitor I use.
>> >
>> > The Pi's display code blanks the screen after a while but this does
>> > not shutdown the monitor.
>> >
>> > I dug a little and it seems I need to send CEC (Consumer Electronics
>> Control)
>> > messages over HDMI - Via a Pi GPU entrypoint.
>> >
>> >
>> > Porting libcec looks a little painful especially as I only need to be
>> able
>> > to send two messages (turn on and turn off).
>> >
>> > Anyone know anything about this stuff? is CEC what I need or is there
>> some
>> > other (simpler) way?
>>
>> May be use a gpio pin to control a switch?!
>>
>>
>

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Re: [9fans] RaspberryPi, monitor energy saving

[erik quanstrom]

On Fri May 16 04:47:03 EDT 2014, steve@quintile.net wrote:

> i believe that this works for vga attached monitors, vesa says that when the clocks
> disappear on the sync the monitor should shutdown.
>
> the raspberry pi uses hdmi and also it doesn't use a vesa bios, it has a gpu bios
> which does a similar job but is not standardised, and, though it is documented,
> it can be tough to use (for me at least).
>
> i am happy to be contradicted on any of this of couse.

i don't have any hdmi monitors, but the vga monitors i do have
will power down when connected to the pi.  i can't check my
source against sources right now since i can't seem to connect.

- erik

Re: [9fans] RaspberryPi, monitor energy saving

[Steve Simon]

Mmm, that feels like good and bad news.

I know richard did what he could to shut down the screen when
its idle for a while so that seems to do the right thing with vga
monitors, but I guess I do need CEC.

Oh well, time for more digging.

-Steve

Re: [9fans] RaspberryPi, monitor energy saving

[erik quanstrom]

On Fri May 16 08:33:41 EDT 2014, steve@quintile.net wrote:
> Mmm, that feels like good and bad news.
>
> I know richard did what he could to shut down the screen when
> its idle for a while so that seems to do the right thing with vga
> monitors, but I guess I do need CEC.
>
> Oh well, time for more digging.

is a hdmi->vga connector too gruesome, or unworkable?

- erik

Re: [9fans] RaspberryPi, monitor energy saving

[Bakul Shah]

> On May 16, 2014, at 5:43 AM, erik quanstrom <quanstro@quanstro.net> wrote:
>
>> On Fri May 16 08:33:41 EDT 2014, steve@quintile.net wrote:
>> Mmm, that feels like good and bad news.
>>
>> I know richard did what he could to shut down the screen when
>> its idle for a while so that seems to do the right thing with vga
>> monitors, but I guess I do need CEC.
>>
>> Oh well, time for more digging.
>
> is a hdmi->vga connector too gruesome, or unworkable?

Adafruit sells one for $19.