tonydowson
Posts: 2
Joined: Fri Apr 22, 2016 2:54 pm

No video output from RISC OS

Fri Apr 22, 2016 3:25 pm

My Raspberry Pi 2 boots successfully from the Raspbian (jessie) SD card, and the GUI seems to work properly. However, I have not been successful with the RISC OS: I bought an appropriate SD card, and as far as I can tell from the flickering of the ACT diode the system is booting correctly, but there is no video, and my monitor complains of 'no signal'.

I am using a VGA monitor with an HDMI-VGA converter, and a wireless mouse and keyboard. These work well with Raspbian, as does the ethernet cable, which seems to suggest that the solution lies elsewhere. But I guess that could be wrong. I've tried disconnecting the dongles and the ethernet cable, but there is still no video signal on boot-up.

The power diode glows a healthy red throughout, so I assume that is not the source of the problem.

Can anyone help?

svrsig
Posts: 134
Joined: Thu Nov 03, 2011 9:45 am
Contact: Website

Re: No video output from RISC OS

Wed Apr 27, 2016 7:37 am

Try setting an explicit monitor resolution in config.txt - most likely the GPU can't work out what you have connected to the HDMI socket and is outputting composite video.

tonydowson
Posts: 2
Joined: Fri Apr 22, 2016 2:54 pm

Re: No video output from RISC OS

Wed Apr 27, 2016 8:59 am

Thank you for this. I've tried various options in config.txt, but none works. I think perhaps the solution might be to buy an HDMI monitor - the VGA monitor belongs to my old desk top which I no longer use.

heuristicjohn
Posts: 39
Joined: Thu Jan 31, 2013 11:55 pm

Re: No video output from RISC OS

Tue Sep 27, 2016 9:38 am

I have a problem when running RISCOS (v 5.2.1 4-6-14) on a Raspberry Pi B+ , in that I get no HDMI output, when connected either to a standard 18" monitor or a 7" car-type LCD display. However, if I put the same SD card (via adaptor) into an RPi B, then the system boots up correctly on either monitor. The RPi B+ card will run Raspbian Jessie when connected to the 18" monitor, so does not appear to be faulty. All connections, cables etc are the same for the RPi B and B+. Any suggestions about how to proceed would be welcome. The config.txt file is as follows:

Code: Select all

# SD M8 card 26-09-16
fake_vsync_isr=1
gpu_mem=32
init_emmc_clock=100000000
kernel=RISCOS.IMG
hdmi_ignore_edid=0xa5000080
hdmi_force_hotplug=1
hdmi_group=2
hdmi_mode=9  #800 x 600
disable_overscan=1

heuristicjohn
Posts: 39
Joined: Thu Jan 31, 2013 11:55 pm

Re: No video output from RISC OS

Tue Sep 27, 2016 10:20 am

To clarify my previous post: I am using two different cards here: one loaded with RISCOS only, the other loaded with Raspbian Jessie only. Apologies for careless wording.

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DavidS
Posts: 4286
Joined: Thu Dec 15, 2011 6:39 am
Location: USA
Contact: Website

Re: No video output from RISC OS

Wed Sep 28, 2016 3:40 am

And you are sure that you have updated the firmware, and installed a new enough RISC OS ROM image?

The RC14 release (which ROOL also sells preloaded on an SD card) has to old of firmware and to old of a ROM build to run on the RPi 2/3.

You have to download a newer ROM build (it will be a nightly build), and update your firmware with newer bootcode/bin, start/elf, and fixup/dat (for non RISC OS users, the forward slash '/' is used in place of the dot in RISC OS for files with .ext type naming, this is do to using the dot as the directory seperator).

With the older firmware it will still attempt to boot, though it will not work. It will flash the SD Card while attempting to get going, and ultimately fail.
RPi = The best ARM based RISC OS computer around
More than 95% of posts made from RISC OS on RPi 1B/1B+ computers. Most of the rest from RISC OS on RPi 2B/3B/3B+ computers

heuristicjohn
Posts: 39
Joined: Thu Jan 31, 2013 11:55 pm

Re: No video output from RISC OS

Wed Sep 28, 2016 12:17 pm

Thanks for your comments. I think I was using RISCOS RC12a (RISCOS screen Info says v5.21(25-Feb-14)); have updated this to ? RC14 (info says v5.21(17-Feb-15)). I found this would run on my RPi B, but not the B+.
HOWEVER, I realised I had another RPi B+ embedded in a project, and when I substituted this (same connections, SD card, PSU etc), it all worked. So it looks as though I have a damaged RPi B+ . I am ordering a new one, which (fingers crossed) should run without problems.
It's quite difficult to wreck an RPi, but looks as though I have finally succeeded ! (I do remember some dodgy wiring...)

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