> 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
In article <hYyEh.27312$OK6.19...@newsfe4-win.ntli.net>, Michael Emerton <MichaelREmer...@hotmail.com> wrote:
> <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
Probably ported from source code that existed in Linux. Have you checked? It could "relatively easy" to recompile under whatever you require.
In message <b0e1a5b94e.b...@Iyonix.woosh.co.nz> b...@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
Jules <julesrichardso...@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.
In message <FAf*Cc...@news.chiark.greenend.org.uk> Theo Markettos <theom+n...@chiark.greenend.org.uk> wrote:
> Jules <julesrichardso...@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
Ron <b...@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
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 Markettos wrote: > Jules <julesrichardso...@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)
Michael Emerton <MichaelREmer...@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 Markettos wrote: > Michael Emerton <MichaelREmer...@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!
Michael Emerton <MichaelREmer...@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
In message <qsw*Br...@news.chiark.greenend.org.uk> Theo Markettos <theom+n...@chiark.greenend.org.uk> wrote:
> Ron <b...@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
> 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
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
Ron <b...@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.
> Ron <b...@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.
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
Ron <b...@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.
In message <IPj*K2...@news.chiark.greenend.org.uk> Theo Markettos <theom+n...@chiark.greenend.org.uk> wrote:
> Ron <b...@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.
Ron <b...@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.
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