RISC PC Powersupply for a car

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Michael Emerton

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Feb 22, 2007, 7:01:45 AM2/22/07
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Does anyone know if there is a power supply which can power an SA RiscPC?

I am intending to convert an SA RiscPC into a car entertainment unit.

I have started writing a piece of software with a decent GUI for use
with an LCD which sits in place of the usual Head unit (I have a remote
Keyboard and mouse to use with this).

but I need the a PSU for a 12 DC Source?

Cheers in advance!

Jules

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Feb 22, 2007, 11:08:48 AM2/22/07
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On Thu, 22 Feb 2007 12:01:45 +0000, Michael Emerton wrote:
> I have started writing a piece of software with a decent GUI for use
> with an LCD which sits in place of the usual Head unit (I have a remote
> Keyboard and mouse to use with this).

Obvious question, but how do you intend to make the device usable (and
safe) at road speeds? Or is the intention to only control it whilst
stopped? Having to use a full keyboard whilst driving sounds like a good
way of ending up dead :(

Seems to be one of those problems with having lots of music instantly on
tap within a car: controlling four or five CDs with ten or so tracks each
is do-able without taking too much concentration away from the driver (as
they can remember CD order and which track is where) - but it really
doesn't scale to thousands on songs.

> but I need the a PSU for a 12 DC Source?

Initially a mains inverter may be an option, depending on how much power
you need. I know Wal-Mart in the US do (or did) a 75W one for something
like the equivalent of £10. Tesco etc. may offer something similar.
Perhaps easier than trying to get regulated 12VDC out of something that
might be anywhere between 11-14VDC and prone to all sorts of spikes.

cheers

Jules

Michael Emerton

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Feb 22, 2007, 11:55:01 AM2/22/07
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<snip>

> Obvious question, but how do you intend to make the device usable (and
> safe) at road speeds? Or is the intention to only control it whilst
> stopped? Having to use a full keyboard whilst driving sounds like a good
> way of ending up dead :(
>
> Seems to be one of those problems with having lots of music instantly on
> tap within a car: controlling four or five CDs with ten or so tracks each
> is do-able without taking too much concentration away from the driver (as
> they can remember CD order and which track is where) - but it really
> doesn't scale to thousands on songs.

Ah! its called a modified keyboard, (and full one) as a uni project, we
managed to munge a keyboard, into some touch-plates which you could
attach to the steering wheel!

so stuff like Left and Right arrow keys = previous / next tracks,

up/down = volume

and Space as Pause/Start

They attempted to use Windows, but on average by the time they booted it
up, short journeys were over!

Hence RISC OS, oh and the fact I have 3 SAs laying around :@P

The full (wireless) keyboard was for searching / setting up playlists
whilst not moving.

Tis a shame it cannot play video well, as it would also be used for
films for my kid on the way :@)

>> but I need the a PSU for a 12 DC Source?
>
> Initially a mains inverter may be an option, depending on how much power
> you need. I know Wal-Mart in the US do (or did) a 75W one for something
> like the equivalent of £10. Tesco etc. may offer something similar.
> Perhaps easier than trying to get regulated 12VDC out of something that
> might be anywhere between 11-14VDC and prone to all sorts of spikes.

Any idea of model numbers?

+ is there a wiring diagram of the RPC power input to the MB? I would
love to get this going asap! :@)

Cheers for the advice so far, am looking!

Jules

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Feb 22, 2007, 1:04:43 PM2/22/07
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On Thu, 22 Feb 2007 16:55:01 +0000, Michael Emerton wrote:
> <snip>
>> <ditto>

>
> Ah! its called a modified keyboard, (and full one) as a uni project, we
> managed to munge a keyboard, into some touch-plates which you could
> attach to the steering wheel!

Aha - interesting. I had a plan once to do this kind of thing, but
couldn't figure out the UI side of it properly - mainly because I tend to
choose my music according to mood, and even with some sort of
collection-based system I still couldn't work out a way of managing what
might be hundreds of different collections whilst on the move. Maybe
that's atypical though and most people have no real preference as to what
song / genre comes up next.

> They attempted to use Windows, but on average by the time they booted it
> up, short journeys were over!

:-)

I was hacking around with a Linux system and diskless booting - I suppose
I could have looked into a board compatible with the Linux BIOS project
to get startup times even quicker (probably in the order of what can be
done with a SARPC)

Eventually that morphed into using the guts of a laptop and a power
inverter - the laptop innards were a lot smaller and meant that the laptop
was a lot less picky about the quality of the input voltage from the
inverter (particularly as the inverter might give up completely during
the couple of seconds whilst the car's started). Not suitable for
production, but a possibility for a "one-off".

I seem to recall pondering on an RPC as an option, but I've got zero clue
as to how to program the buggers :-)

>>> but I need the a PSU for a 12 DC Source?
>>
>> Initially a mains inverter may be an option, depending on how much
>> power you need. I know Wal-Mart in the US do (or did) a 75W one for
>> something like the equivalent of £10. Tesco etc. may offer something
>> similar. Perhaps easier than trying to get regulated 12VDC out of
>> something that might be anywhere between 11-14VDC and prone to all
>> sorts of spikes.
>
> Any idea of model numbers?

I suspect it may have been replaced by this:

http://www.walmart.com/catalog/product.do?product_id=4891078

... which works out at about a tenner and gives you 100W at 110VAC. Unless
the SARPC PSU is jumper (or automatically) selectable for 110V operation
though you'll need 220VAC for a UK PSU (and I suppose a similarly-sized
inverter will give you 50W to play with rather than 100W)

Maybe the company making the above also produces equivalents for the UK
market, though.

I'm in the US right now and might be heading to WalMart this evening, so
if I get the chance I'll have a quick look on the shelves to see what
other goodies they might have.

cheers

Jules

druck

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Feb 22, 2007, 1:17:14 PM2/22/07
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On 22 Feb 2007 Michael Emerton <Michael...@hotmail.com> wrote:
> Does anyone know if there is a power supply which can power an SA RiscPC?
>
> I am intending to convert an SA RiscPC into a car entertainment unit.

A Risc PC? In a car or hummvee? Why not an A9, its ideally sized for such an
application.

---druck

--
The ARM Club Free Software - http://www.armclub.org.uk/free/
The 32bit Conversions Page - http://www.quantumsoft.co.uk/druck/

Message has been deleted

News poster

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Feb 22, 2007, 2:04:19 PM2/22/07
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In message <bc3244b9...@druck.freeuk.net>
druck <ne...@druck.freeuk.com> wrote:

> On 22 Feb 2007 Michael Emerton <Michael...@hotmail.com> wrote:
> > Does anyone know if there is a power supply which can power an SA RiscPC?
> >
> > I am intending to convert an SA RiscPC into a car entertainment unit.
>
> A Risc PC? In a car or hummvee? Why not an A9, its ideally sized for such an
> application.

1) A RiscPC you already have is free, you don't need to worry about
warrantly claims should you break it?

2) Still apparently some stability and support issues with the A9home OS
(please feel free to correct me if my perceptions are wrong)?

3) Fitting a larger hard drive in a RiscPC is easier than fitting one in
an A9Home.

The A9home does have a size advantage and is already neatly packaged up.

On the other hand using a RiscPC as a prototype makes a lot of sense. If
the software/hardware is usable on a RiscPC it should be fine on a
faster A9home.

Out of curiousuty is there an approved PSU that allows the A9home to run
off a 12v supply as in a car?

Cheers
Stan
--
http://mistymornings.net

druck

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Feb 22, 2007, 2:03:14 PM2/22/07
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On 22 Feb 2007 Paul Vigay <invalid-em...@invalid-domain.co.uk> wrote:
> In article <bc3244b9...@druck.freeuk.net>,

> druck <ne...@druck.freeuk.com> wrote:
> > A Risc PC? In a car or hummvee? Why not an A9, its ideally sized for such
> > an application.
>
> If, as he said, he's got 3 RPCs lying around then it might work out
> slightly cheaper than an A9....

But you'll be laughed at for using something the size of a Risc PC.

Stuart

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Feb 22, 2007, 1:22:01 PM2/22/07
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In article <pan.2007.02.22....@remove.this.yahoo.co.uk>,

Jules <julesric...@remove.this.yahoo.co.uk> wrote:
> I suspect it may have been replaced by this:

> http://www.walmart.com/catalog/product.do?product_id=4891078

> ... which works out at about a tenner and gives you 100W at 110VAC.
> Unless the SARPC PSU is jumper (or automatically) selectable for 110V
> operation though you'll need 220VAC for a UK PSU (and I suppose a
> similarly-sized inverter will give you 50W to play with rather than 100W)

I'd been thinking of getting one of these:

http://cpc.farnell.com/jsp/search2/browse.jsp?N=500009+401+411&Ntk=gensearch_003&Ntt=CP0434003&Ntx=&_requestid=608999

Compressor, jump starter, 100W inverter...

In case that doesn't work search for CP0434003 at www.cpc.co.uk

but simple inverters are available, just go to home page (above) and
search for inverter.

Stuart
(No connection with CPC other than as a customer)

--
Stuart Winsor

From is valid but subject to change without notice if it gets spammed.

For Barn dances and folk evenings in the Coventry and Warwickshire area
See: http://www.barndance.org.uk

Michael Emerton

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Feb 22, 2007, 2:42:49 PM2/22/07
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druck wrote:
> On 22 Feb 2007 Paul Vigay <invalid-em...@invalid-domain.co.uk> wrote:
>> In article <bc3244b9...@druck.freeuk.net>,
>> druck <ne...@druck.freeuk.com> wrote:
>>> A Risc PC? In a car or hummvee? Why not an A9, its ideally sized for such
>>> an application.
>> If, as he said, he's got 3 RPCs lying around then it might work out
>> slightly cheaper than an A9....
>
> But you'll be laughed at for using something the size of a Risc PC.
>
> ---druck
>


at the end of the day, I have sourced a case, and it's functional..hence
why I have a Peugeot 106 Diesel!

Never conformed to fashion!

Message has been deleted

Ron

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Feb 22, 2007, 5:30:34 PM2/22/07
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In message <JCfDh.29909$Da4....@newsfe6-gui.ntli.net>
Michael Emerton <Michael...@hotmail.com> wrote:

I have just changed the harddrive for a 1 GB compactflash on my RiscPC
using this very cheap item from ebay.
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=150086370137
It would help drop the power requirements.
The RiscPC powersupply is noisy even after removing the fan. (buzzes).
My approach would be to use DC power and bypass the psu. I'm not sure
what chips use the -12 and -5V lines but they may be OK with batterys
and an alternative charger or solar panel.
The other thing that springs to mind is the use of alternating current
from the car alternator to drive a +/- psu. Just a few ideas...
Cheers -Ron

druck

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Feb 22, 2007, 6:04:13 PM2/22/07
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On 22 Feb 2007 News poster <mistym...@casema.nl> wrote:
> 1) A RiscPC you already have is free, you don't need to worry about
> warrantly claims should you break it?
>
> 2) Still apparently some stability and support issues with the A9home OS
> (please feel free to correct me if my perceptions are wrong)?
>
> 3) Fitting a larger hard drive in a RiscPC is easier than fitting one in
> an A9Home.
>
> The A9home does have a size advantage and is already neatly packaged up.
>
> On the other hand using a RiscPC as a prototype makes a lot of sense. If
> the software/hardware is usable on a RiscPC it should be fine on a
> faster A9home.

But if someone comes up with useful and good looking in car system based
around and A9 and a small LCD display, they might be able to make quite a
few pennies by selling it to others. Its something I've considered.

Rob Kendrick

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Feb 22, 2007, 6:41:25 PM2/22/07
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On Thu, 22 Feb 2007 23:04:13 +0000, druck wrote:

>> On the other hand using a RiscPC as a prototype makes a lot of sense. If
>> the software/hardware is usable on a RiscPC it should be fine on a
>> faster A9home.
>
> But if someone comes up with useful and good looking in car system based
> around and A9 and a small LCD display, they might be able to make quite a
> few pennies by selling it to others. Its something I've considered.

You might want to talk to Advantage Six directly on that one: I seem to
recall that the SM501 video chip-set has an LCD controller built-in, and
you may be better off using that output rather than then VGA. (I'm
assuming that the LVDS is sent to a pin-out somewhere.) Thus, you'd want
A6 to make you A9s with this exposed on the casework to avoid voiding any
warranties.

I've looked into it too; although only really as a mechanism to dump
photos off my camera while away from home, and provide some interface for
viewing/deleting/etc them. Alas, I think the CPU might be a little too
puny for doing RAW conversions for this.

If you make any progress on this - I'm interested.

B.

Stuart

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Feb 22, 2007, 6:07:37 PM2/22/07
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In article <4eb9592fafinval...@invalid-domain.co.uk>,
Paul Vigay <invalid-em...@invalid-domain.co.uk> wrote:
> Or even off six volts - I'm thinking of four AA batteries (or possibly 3 or
> 4 sets of four in parallel)

Not a good idea to parallel batteries, you can get circulating currents
and they are unlikely to share the load equally. You can get round the
first problem by paralleling each set through a diode (since you have 6V
and want 5V this is not a bad thing as it will drop the voltage) but not
the latter

Stuart

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Feb 22, 2007, 6:08:51 PM2/22/07
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In article <pan.2007.02.22....@rjek.com>,

Rob Kendrick <nn...@rjek.com> wrote:
> You might want to talk to Advantage Six directly on that one:

That is certainly the best solution

Michael Emerton

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Feb 23, 2007, 4:47:02 AM2/23/07
to

Cheers.

There are PSUs for PCs, for use in cars available, but of course do not
have the PSU block that the RPC requires.

have thought about munging one of these into the RPC, but alas no idea
what the pin in's are on the board?

Or is there an ATX > RPC converter? I have seen many RPC case mods
using standard ATX PSUs?

I have a compact flash converter, but alas my new camera uses the
buggers now (old one used SD)

Alan Wrigley

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Feb 23, 2007, 5:20:37 AM2/23/07
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In message <pan.2007.02.22....@rjek.com>
Rob Kendrick <nn...@rjek.com> wrote:

> You might want to talk to Advantage Six directly on that one: I seem to
> recall that the SM501 video chip-set has an LCD controller built-in, and
> you may be better off using that output rather than then VGA. (I'm
> assuming that the LVDS is sent to a pin-out somewhere.) Thus, you'd want
> A6 to make you A9s with this exposed on the casework to avoid voiding any
> warranties.
>
> I've looked into it too; although only really as a mechanism to dump
> photos off my camera while away from home, and provide some interface for
> viewing/deleting/etc them.

This latter idea has been at the back of my mind ever since the A9 was
first announced, so I certainly might be interested. More expensive
than the Epson photo viewers but you do get a full RO computer thrown
in.

Alan

--
RISC OS - you know it makes cents

Ron

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Feb 23, 2007, 7:04:12 AM2/23/07
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In message <qKyDh.14135$Zl6....@newsfe3-win.ntli.net>
Michael Emerton <Michael...@hotmail.com> wrote:

> Cheers.
>
> There are PSUs for PCs, for use in cars available, but of course do not
> have the PSU block that the RPC requires.
>
> have thought about munging one of these into the RPC, but alas no idea
> what the pin in's are on the board?
>
> Or is there an ATX > RPC converter? I have seen many RPC case mods
> using standard ATX PSUs?
>
> I have a compact flash converter, but alas my new camera uses the
> buggers now (old one used SD)

Ok, it sounds like you dont have a multimeter either, which may make it
difficult to check your work when making the new connections.

The RiscPC connector is: Red +5v
Red +5v
Black 0v
Black 0v
Yellow +12v
Blue -12v

There are standard colours on most ATX psu's but it would pay to check
at least the +12v and -12v lines. From memory, the purple wire somewhere
near the center of the atx connector gets grounded to turn the psu on.
So it would be possible, and probably much more efficient than using an
inverter. If it is only a temporary project you might not feel like
hacking up a good Acorn psu, I dont know.
Cheers _Ron

Michael Emerton

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Feb 23, 2007, 7:47:53 AM2/23/07
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<snip>

> The RiscPC connector is: Red +5v
> Red +5v
> Black 0v
> Black 0v
> Yellow +12v
> Blue -12v
>
> There are standard colours on most ATX psu's but it would pay to check
> at least the +12v and -12v lines. From memory, the purple wire somewhere
> near the center of the atx connector gets grounded to turn the psu on.
> So it would be possible, and probably much more efficient than using an
> inverter. If it is only a temporary project you might not feel like
> hacking up a good Acorn psu, I dont know.
> Cheers _Ron
>

Cheers for the info, have saved it :@)

the psu I was thinking about was:
http://www.mini-box.com/M1-ATX-90w-Intelligent-Automotive-DC-DC-Power-Supply;jsessionid=ac112b2a1f43281296946b304e6eb8d9a6bc04cb8047.e3eSbNyQc3mLe34ObhmSa30Na3b0n6jAmljGr5XDqQLvpAe?sc=8&category=101

Theo Markettos

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Feb 24, 2007, 11:00:18 AM2/24/07
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Ron <be...@woosh.co.nz> wrote:
> The RiscPC powersupply is noisy even after removing the fan. (buzzes).
> My approach would be to use DC power and bypass the psu. I'm not sure
> what chips use the -12 and -5V lines but they may be OK with batterys
> and an alternative charger or solar panel.

Being lazy and not digging out the circuits, IIRC the -12V is used for the
serial port and the -5V for audio. So if you're not bothered about those
you could decide not to provide them. +12V is required for video output, so
you will need that. Otherwise they take relatively little current so a
DC-DC converter may be sufficient (but an ICL7660 isn't enough).

> The other thing that springs to mind is the use of alternating current
> from the car alternator to drive a +/- psu. Just a few ideas...

Sounds nasty... lots of noise from sparkplugs etc around there, and it's not
going to be 50Hz. Probably better to go the DC-DC converter route from the
battery.

Theo

Dave Higton

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Feb 24, 2007, 3:56:26 PM2/24/07
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In message <EEj*eH...@news.chiark.greenend.org.uk>
Theo Markettos <theom...@chiark.greenend.org.uk> wrote:

> Ron <be...@woosh.co.nz> wrote:
> > The RiscPC powersupply is noisy even after removing the fan. (buzzes).
> > My approach would be to use DC power and bypass the psu. I'm not sure
> > what chips use the -12 and -5V lines but they may be OK with batterys
> > and an alternative charger or solar panel.
>
> Being lazy and not digging out the circuits, IIRC the -12V is used for the
> serial port and the -5V for audio. So if you're not bothered about those
> you could decide not to provide them.

If you decide not to provide them, I'd recommend that you short those
lines to 0V rather than leaving them open. Any devices connected to
the lines would otherwise possibly draw current through paths that
weren't designed to permit that on a continuous basis. Their long
term reliability might be affected. Simply shorting the lines to 0V
is a simple way of avoiding any possible such problem.

Dave

Michael Emerton

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Feb 24, 2007, 5:31:05 PM2/24/07
to
<snip>

Otherwise they take relatively little current so a
> DC-DC converter may be sufficient (but an ICL7660 isn't enough).
>
>> The other thing that springs to mind is the use of alternating current
>> from the car alternator to drive a +/- psu. Just a few ideas...
>
> Sounds nasty... lots of noise from sparkplugs etc around there, and it's not
> going to be 50Hz. Probably better to go the DC-DC converter route from the
> battery.

good I have a Diesel then ;@)

should this be ok, If i Munge the connections into a RPC one?


http://www.mini-box.com/M1-ATX-90w-Intelligent-Automotive-DC-DC-Power-Supply;jsessionid=ac112b2a1f43281296946b304e6eb8d9a6bc04cb8047.e3eSbNyQc3mLe34ObhmSa30Na3b0n6jAmljGr5XDqQLvpAe?sc=8&category=101

http://store.mp3car.com/ProductDetails.asp?ProductCode=PWR%2D004

just interested as I can get one for free :@)

Theo Markettos

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Feb 25, 2007, 9:23:22 AM2/25/07
to

That should be OK... provides +5, +12, -12. No -5 but that's not a big deal
unless you want audio. It's designed for car use, which is good. It
doesn't say what the minimum current draw it can cope with is, but given it
talks about standby modes they've hopefully thought of that.

> http://store.mp3car.com/ProductDetails.asp?ProductCode=PWR%2D004

That doesn't give many details. If it's free then give it a try and it'll
probably be OK, but otherwise go for the other one.

Theo

Ron

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Feb 25, 2007, 6:00:05 PM2/25/07
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In message <kWb*2B...@news.chiark.greenend.org.uk>
Theo Markettos <theom...@chiark.greenend.org.uk> wrote:

> Michael Emerton <Michael...@hotmail.com> wrote:
> > good I have a Diesel then ;@)
> >
> > should this be ok, If i Munge the connections into a RPC one?
> >
> > http://www.mini-box.com/M1-ATX-90w-Intelligent-Automotive-DC-DC-Power-Supply;jsessionid=ac112b2a1f43281296946b304e6eb8d9a6bc04cb8047.e3eSbNyQc3mLe34ObhmSa30Na3b0n6jAmljGr5XDqQLvpAe?sc=8&category=101
>
> That should be OK... provides +5, +12, -12. No -5 but that's not a big deal
> unless you want audio. It's designed for car use, which is good. It
> doesn't say what the minimum current draw it can cope with is, but given it
> talks about standby modes they've hopefully thought of that.
>

The RiscPC connector doesn't have -5v anyway, there must be an onboard
regulator that gets it from the -12v. So no problem.

> > http://store.mp3car.com/ProductDetails.asp?ProductCode=PWR%2D004
>
> That doesn't give many details. If it's free then give it a try and it'll
> probably be OK, but otherwise go for the other one.
>
> Theo

The pin size of the mainboard power connector seesms to be around
between 2-2.3mm maybe 3/32 inch. There may be individual dc power plugs
(the type with the hole) that would work, otherwise its cut the wires
and use a connector.
The round automotive crimp type connectors are quite firm and would
allow you to reconnect the original power supply for indoor use.
The hold the crimp fitting gets on the insulation is sometimes wobbly
but if it is not a good fit you could beef it up with some glue.
I'm assumimg here that the original 6 pin plug is not available.
I have an old Farnell catalogue, and I'll have a look later.
Cheers -Ron

Jules

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Feb 25, 2007, 7:24:44 PM2/25/07
to
On Sat, 24 Feb 2007 16:00:18 +0000, Theo Markettos wrote:

> Ron <be...@woosh.co.nz> wrote:
>> The RiscPC powersupply is noisy even after removing the fan. (buzzes).
>> My approach would be to use DC power and bypass the psu. I'm not sure
>> what chips use the -12 and -5V lines but they may be OK with batterys
>> and an alternative charger or solar panel.
>
> Being lazy and not digging out the circuits, IIRC the -12V is used for the
> serial port and the -5V for audio. So if you're not bothered about those
> you could decide not to provide them. +12V is required for video output, so
> you will need that.

Hmm. For a car system with an LCD (presumably run via a serial or parallel
port?) as the main display, there's no *need* for normal graphical video
output either. Whether the system would power up and initialise without
any video is another matter.

Of course maybe the "correct" way of doing this is to ditch the
OS ROMs altogether and roll your own bespoke app which talks to
the bare hardware and lives in the normal ROM sockets - any
attached disks are then purely for entertainment data.

Ron

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Feb 26, 2007, 12:33:53 AM2/26/07
to
In message <cd99e9b...@Iyonix.woosh.co.nz>
be...@woosh.co.nz (Ron) wrote:
<snip other method>

> I'm assumimg here that the original 6 pin plug is not available.
> I have an old Farnell catalogue, and I'll have a look later.
> Cheers -Ron
>
Ok, I've looked and there is a plug that looks too close to be anything
else. It has the same hole spacing and the two keying holes with flats.

AMP 1-480704-0 Farnell Order code: .285-183

Alternatively, I bought six inserts that are a good fit, they will need
a bit of insulation slipped over the protuding ends and will need extra
caution for correct positioning. The description for them is:

24-18 AWG AMP UniMate N-lock socket (6 required)

Cheers -Ron

Michael Emerton

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Feb 26, 2007, 5:50:53 AM2/26/07
to
<snip>

> Of course maybe the "correct" way of doing this is to ditch the
> OS ROMs altogether and roll your own bespoke app which talks to
> the bare hardware and lives in the normal ROM sockets - any
> attached disks are then purely for entertainment data.
>

this is a good idea

only slight problem, just slightly out of my scope ;@)

And I cannot use the Ogg player from Peter Nulls as I am assuming it
needs RISC OS :@P

Steven Pampling

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Feb 26, 2007, 6:49:09 AM2/26/07
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In article <hYyEh.27312$OK6....@newsfe4-win.ntli.net>,

Probably ported from source code that existed in Linux. Have you checked?
It could "relatively easy" to recompile under whatever you require.

Ron

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Feb 27, 2007, 5:28:52 PM2/27/07
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In message <b0e1a5b...@Iyonix.woosh.co.nz>
be...@woosh.co.nz (Ron) wrote:

> The RiscPC connector is: Red +5v
> Red +5v
> Black 0v
> Black 0v
> Yellow +12v
> Blue -12v
>
> There are standard colours on most ATX psu's but it would pay to check
> at least the +12v and -12v lines. From memory, the purple wire somewhere
> near the center of the atx connector gets grounded to turn the psu on.

Just to correct myself, it is the green wire (not purple) on the ATX
mainboard connector that is the soft-power line. It is the 4th from one
end and it needs to be grounded to get power from the ATX psu.
Cheers -Ron

Theo Markettos

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Feb 27, 2007, 6:44:51 PM2/27/07
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Jules <julesric...@remove.this.yahoo.co.uk> wrote:
> Hmm. For a car system with an LCD (presumably run via a serial or parallel
> port?) as the main display, there's no *need* for normal graphical video
> output either. Whether the system would power up and initialise without
> any video is another matter.

IIRC the +12V is required for the analogue video output. So it'll work
quite happily with no +12V, it's just like nothing is connected to the
monitor port. Also you can switch the VIDC into digital out (to the Genlock
header) and it won't need +12V - you can then drive a laptop screen LCD from
that.

> Of course maybe the "correct" way of doing this is to ditch the
> OS ROMs altogether and roll your own bespoke app which talks to
> the bare hardware and lives in the normal ROM sockets - any
> attached disks are then purely for entertainment data.

Well, that sounds a bit hairy, given you'd have to write your own IDE,
serial, etc drivers, worry about the MMU, cache, interrupts and so on. No
doubt you could install an ARM micro-OS, but RISC OS is almost as good as
that for this application. What you could do is roll your own RISC OS ROMs
with all the other software in ROM (there's an article on the technical
documents page on my website to do this in RO3.1), but loading a few bits
off compactflash isn't a big deal.

Theo

--
Theo Markettos th...@markettos.org.uk
Clare Hall, Cambridge at...@cam.ac.uk
CB3 9AL, UK http://www.markettos.org.uk/

Ron

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Feb 27, 2007, 8:11:13 PM2/27/07
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In message <FAf*Cc...@news.chiark.greenend.org.uk>
Theo Markettos <theom...@chiark.greenend.org.uk> wrote:

> Jules <julesric...@remove.this.yahoo.co.uk> wrote:
> > Hmm. For a car system with an LCD (presumably run via a serial or parallel
> > port?) as the main display, there's no *need* for normal graphical video
> > output either. Whether the system would power up and initialise without
> > any video is another matter.
>
> IIRC the +12V is required for the analogue video output. So it'll work
> quite happily with no +12V, it's just like nothing is connected to the
> monitor port. Also you can switch the VIDC into digital out (to the Genlock
> header) and it won't need +12V - you can then drive a laptop screen LCD from
> that.

Not having to use 12v would help in keeping the computer alive during
engine cranking, a problem that some dc-dc supplys have. If it wasn't
for the -5v needed for the audio all you would need is a heavy +5v
regulator.

I would like to now more about how to do the lcd connections as this
would obviously be a big power saver. This would be a great project
especially nowadays with the advances of LCD's, Solar panels, batteries
and so on. TIA -Ron

Theo Markettos

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Feb 28, 2007, 9:27:56 AM2/28/07
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Ron <be...@woosh.co.nz> wrote:
> I would like to now more about how to do the lcd connections as this
> would obviously be a big power saver. This would be a great project
> especially nowadays with the advances of LCD's, Solar panels, batteries
> and so on. TIA -Ron

http://www.markettos.org.uk/riscos/a4/lcd7500.html

has details for the rather strange Acorn A4 monochrome panel, but it links
to an ARM application note which tells you (section B) how to attach a
colour LCD to an ARM7500. The ARM7500 contains a VIDC20, so the same should
apply to a Risc PC (though I haven't actually tried it).

Theo

Michael Emerton

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Feb 28, 2007, 11:07:13 AM2/28/07
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<snip>

>> only slight problem, just slightly out of my scope ;@)
>
>> And I cannot use the Ogg player from Peter Nulls as I am assuming it
>> needs RISC OS :@P
>
> Probably ported from source code that existed in Linux. Have you checked?
> It could "relatively easy" to recompile under whatever you require.

I am not a big time coder / compiler, I work in BBC Basic ;@,

but I believe you are correct in that it is from linux.

Michael Emerton

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Mar 4, 2007, 12:37:36 PM3/4/07
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Theo Markettos wrote:
> Jules <julesric...@remove.this.yahoo.co.uk> wrote:
>> Hmm. For a car system with an LCD (presumably run via a serial or parallel
>> port?) as the main display, there's no *need* for normal graphical video
>> output either. Whether the system would power up and initialise without
>> any video is another matter.
>
> IIRC the +12V is required for the analogue video output. So it'll work
> quite happily with no +12V, it's just like nothing is connected to the
> monitor port. Also you can switch the VIDC into digital out (to the Genlock
> header) and it won't need +12V - you can then drive a laptop screen LCD from
> that.

Could I connect up a TFT (Harvested from a damaged home screen) which is
in colour? (1024 X 768 X 256)

Or is it still restricted to 640x480x4?

Theo Markettos

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Mar 4, 2007, 2:53:22 PM3/4/07
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Michael Emerton <Michael...@hotmail.com> wrote:
> Could I connect up a TFT (Harvested from a damaged home screen) which is
> in colour? (1024 X 768 X 256)

Yes, assuming it has a parallel input (nothing to do with parallel printer
ports). See the colour panel section of the ARM datasheet linked from my
page for the sort of thing it means. Some more modern screens use LVDS (low
voltage differential signalling, a form of serial input) for which Simtec
make a converter between the Risc PC and LVDS (actually it's for their
RiscStation board, but it should work on a RPC too). Do you have the
datasheet for you panel, or can you find it on the net? That'll be the
first place to start.

> Or is it still restricted to 640x480x4?

No, though the VIDC's digital out is only 8 bits wide, so for 16-bit
displays you have to double-clock it, which means you might hit the VIDC's
bandwidth limits. I can't remember exactly what the limit is, but I'm sure
800x600 has been done so don't see why 1024x768 at 8 bit shouldn't be
possible.

Theo

Michael Emerton

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Mar 6, 2007, 8:28:51 AM3/6/07
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Theo Markettos wrote:
> Michael Emerton <Michael...@hotmail.com> wrote:
>> Could I connect up a TFT (Harvested from a damaged home screen) which is
>> in colour? (1024 X 768 X 256)
>
> Yes, assuming it has a parallel input (nothing to do with parallel printer
> ports). See the colour panel section of the ARM datasheet linked from my
> page for the sort of thing it means. Some more modern screens use LVDS (low
> voltage differential signalling, a form of serial input) for which Simtec
> make a converter between the Risc PC and LVDS (actually it's for their
> RiscStation board, but it should work on a RPC too). Do you have the
> datasheet for you panel, or can you find it on the net? That'll be the
> first place to start.

Slight problem there, its a cheap LCD (£100 over 4 years ago!) and I
have no idea where it came from, as my Parents brought it.

As the screen is so old, I assume its parellel?

I will do some digging.


>> Or is it still restricted to 640x480x4?
>
> No, though the VIDC's digital out is only 8 bits wide, so for 16-bit
> displays you have to double-clock it, which means you might hit the VIDC's
> bandwidth limits. I can't remember exactly what the limit is, but I'm sure
> 800x600 has been done so don't see why 1024x768 at 8 bit shouldn't be
> possible.


I hadn't realised this was possible! 800x600 would be ok, but latter
would be better for listing Music Data!

Theo Markettos

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Mar 6, 2007, 2:38:43 PM3/6/07
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Michael Emerton <Michael...@hotmail.com> wrote:
> Slight problem there, its a cheap LCD (?100 over 4 years ago!) and I
> have no idea where it came from, as my Parents brought it.
>
> As the screen is so old, I assume its parellel?

Very much depends. I haven't taken a desktop LCD apart, but it might be the
panel doesn't have the same interface as in a laptop.



> I will do some digging.

Start looking for model numbers on the LCD or the chips on it and having a
Google will probably be the best way. This discussion forum is probably the
best resource for LCD info on the net:
http://www.eio.com/lcdintro.htm

Theo

Ron

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Mar 13, 2007, 1:23:57 AM3/13/07
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In message <qsw*Br...@news.chiark.greenend.org.uk>
Theo Markettos <theom...@chiark.greenend.org.uk> wrote:

I've just had a look through the LCD for 7500 application note, and it
appears that one could build a circuit to drive a 256 colour display at
800*600. But there was a BASIC program available from ART needed as
well.
I'm not sure how it would be implemented but I can see that the RISCOS
LCD driver is only 4 bit greyscale.
TIA -Ron

Theo Markettos

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Apr 25, 2007, 9:51:57 AM4/25/07
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Ron <be...@woosh.co.nz> wrote:
> I've just had a look through the LCD for 7500 application note, and it
> appears that one could build a circuit to drive a 256 colour display at
> 800*600. But there was a BASIC program available from ART needed as
> well.

The program just pokes a few VIDC registers to enable the LCD output, it
doesn't do anything special.

> I'm not sure how it would be implemented but I can see that the RISCOS
> LCD driver is only 4 bit greyscale.

There isn't a RISC OS LCD driver AFAIK - on the A4 the VIDC is programmed to
send data through its digital output port, and the LCD ASIC does the rest.

The 7500(FE) has most of this stuff internally, so all you need to do is
poke the relevant VIDC registers and you either get dual-scan greyscale
(dual-scan 640x480=you write data to line x and line x+240 at the same
time), or single panel colour. Look at my driver module on the page I
linked to - this just pokes a few VIDC registers and the LCD data comes out
the digital port. Most of it is trying to work around the problem that, on
dual-scan panels, the pointer location has to be carefully specified to draw
it in the right place.

Get a copy of the ARM7500FE and VIDC20 datasheets for details of the
registers.

http://www.drobe.co.uk/reference/early_datasheets/ for VIDC20

Theo

Ron

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Apr 26, 2007, 7:43:16 AM4/26/07
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In message <52h*-C9...@news.chiark.greenend.org.uk>
Theo Markettos <theom...@chiark.greenend.org.uk> wrote:

Thanks, I will have another look sometime.
It sounds like a 7500(FE) machine would be desirable for such a project,
and being newer than a RiscPC would probably need less power to run.
About the PSU voltage requirements of the RiscPC, I found that the
machine will boot up and run without the -12V but it falls short of the
beep and has no display output with the +12V disconnected.
I adapted an old PC psu (minus fan) into the RiscPC that also has a CF
adapter for HD, and now have a silent machine. :-)
Cheers -Ron

Theo Markettos

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Apr 28, 2007, 7:57:06 AM4/28/07
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Ron <be...@woosh.co.nz> wrote:
> Thanks, I will have another look sometime.
> It sounds like a 7500(FE) machine would be desirable for such a project,
> and being newer than a RiscPC would probably need less power to run.

That would make sense... it's smaller too.

> About the PSU voltage requirements of the RiscPC, I found that the
> machine will boot up and run without the -12V but it falls short of the
> beep and has no display output with the +12V disconnected.

It should run - the audio and video outputs need +12V but I think the rest
of the machine should carry on without noticing.

> I adapted an old PC psu (minus fan) into the RiscPC that also has a CF
> adapter for HD, and now have a silent machine. :-)

:) What model of CF card did you use? I've been having strange results
with my collection of assorted CF cards... I haven't actually formatted one
to Filecore yet, but they seem to behave oddly to ADFS_SectorDiscOp
commands.

Theo

Ron

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Apr 29, 2007, 6:45:28 AM4/29/07
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In message <IPj*K2...@news.chiark.greenend.org.uk>
Theo Markettos <theom...@chiark.greenend.org.uk> wrote:

> Ron <be...@woosh.co.nz> wrote:
> > Thanks, I will have another look sometime.
> > It sounds like a 7500(FE) machine would be desirable for such a project,
> > and being newer than a RiscPC would probably need less power to run.
>
> That would make sense... it's smaller too.
>
> > About the PSU voltage requirements of the RiscPC, I found that the
> > machine will boot up and run without the -12V but it falls short of the
> > beep and has no display output with the +12V disconnected.
>
> It should run - the audio and video outputs need +12V but I think the rest
> of the machine should carry on without noticing.
>

Maybe it is, with no video I cant see, What does the startup beep
indicate? Maybe it knows that the video is down, I dont know.

> > I adapted an old PC psu (minus fan) into the RiscPC that also has a CF
> > adapter for HD, and now have a silent machine. :-)
>
> :) What model of CF card did you use? I've been having strange results
> with my collection of assorted CF cards... I haven't actually formatted one
> to Filecore yet, but they seem to behave oddly to ADFS_SectorDiscOp
> commands.
>
> Theo

I have only ever formatted abot 3 cards to Risc OS and have never
encounterd a problem and assumed all cards would be OK. The card I am
using is a Kingston 1024MB. Its just the old standard speed type. I have
an old RCA MP3 player which is a bit picky (dos errors), so I tend to go
for bigger namebrands like lexar, sandisk and these kingston ones seem
to be OK. There will of course be many other good ones.

Cheers -Ron

Theo Markettos

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May 2, 2007, 1:17:00 PM5/2/07
to
Ron <be...@woosh.co.nz> wrote:
> Maybe it is, with no video I cant see, What does the startup beep
> indicate? Maybe it knows that the video is down, I dont know.

I think the startup beep comes from the OS, so it indicates the OS is
running. The +12V line powers:

The clean +5V rail for the VIDC's onboard audio DAC via a 12->5 regulator
The LM324 audio amplifier from the same clean +5V rail
The two audio output transistors
VGA socket pin 12 (for switching SCART monitors)
The VIDC20 VCO (voltage controlled oscillator), used to generate pixel
clocks
The serial port line drivers

Without +12V you'd get no audio output, but (probably) the VIDC won't
notice. You'll get no video output due to the lack of VCO. However, since
the VIDC is write-only there's no way for the OS to read back its status and
notice any of these things. However the OS may notice the absence of flyback
interrupts, which would be caused by lack of a pixel clock (and hence VCO
not running).

Probably the best thing to do is connect the +12V input to +5V. That way
you'll probably get quiet and distorted audio, and the VCO may run but too
slow (if it does at all). If it does you might need to play with your
monitor definition file to produce timings that suit your monitor, but it's
probably best to assume there will be no video.

> I have only ever formatted abot 3 cards to Risc OS and have never
> encounterd a problem and assumed all cards would be OK. The card I am
> using is a Kingston 1024MB. Its just the old standard speed type. I have
> an old RCA MP3 player which is a bit picky (dos errors), so I tend to go
> for bigger namebrands like lexar, sandisk and these kingston ones seem
> to be OK. There will of course be many other good ones.

Interesting. I've just found my Kingston 512MB card, so I'll give it a go.

Theo

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