Atrix Lapdock -> RISC OS Portable

I’ve managed to dock my Beagle xM with my (original) Atrix lapdock, using the instructions here (albeit with different cables and adaptors). I can’t help feeling the Beagle is a bit big and heavy for it to work properly, but with the RPi being restricted to 1080p, I can’t use that as the lapdock needs a 1366×768 resolution, which the Beagleboard can do!

I used a microHDMI female to HDMI male adaptor, and plugged the Beagle into the mains. I’m awaiting one of these cables to adapt it into a split cable to power a Pi from the internal battery, and use the keyboard and trackpad on the lapdock for input.

How difficult is it to make a new RPi ROM with the 1366×768 resolution? Or could someone knock one up for me to test RISC OS on a new potential portable? I don’t have any means of compiling a ROM, if that’s what is necessary.

given that the Lapdocks are between £60-90 from here for example, these days, and the RPi is £25ish, it makes for a very cheap, if not slightly ugly replacement for the A4!

So, can anyone help me test the RPi Lapdock option?

Very interesting. How long can you run the xM (and screen) on the in-built batteries?

None at all yet. Still awaiting the cable that allows me to utilise the battery. Indications are that 4hrs isn’t beyond the realms of possibility though, with an RPI, which I guess isn’t that much different. Just need the RPI ROM with an appropriate resolution (and the cable) to put it to the test! Once the cable arrives, I’ll let you know a more definitive battery life for both boards.

How difficult is it to make a new RPi ROM with the 1366×768 resolution?

Its not that hard. I should be able to run one up tonight if no one else has by then.

The GPU on the RPi should scale the 1080P output from RISC OS to whatever the monitor requires, so it should be possible to get a display up and running with the standard ROM image, it may just be difficult to read.

The GPU on the RPi should scale the 1080P output from RISC OS to whatever the monitor requires, so it should be possible to get a display up and running with the standard ROM image, it may just be difficult to read.

I tried it with hdmi_mode=39 set in the config.txt file to no avail. Still didn’t seem to work. Just said no HDMI input. I might have to wiggle with the cables though, because on the Beagleboard it says “Out Of Range” if I leave it set to 1920×1080.

I’ve built a RPi ROM from the 5th August. The actual resolution is set to 1360×768, as that seems to be the correct one (It doesn’t display correctly with 1366).

File can be downloaded from http://www.mybigideas.co.uk/files/RPiRO768.zip

I tried it with hdmi_mode=39

I tried that too (with hdmi_group=2) and my monitor ended up doing 640×480....

Let me know if it works for you

Let me know if it works for you

I just get a rainbow screen of death thing! Does nothing beyond that. Do I need something specific in the config.txt file?

I just get a rainbow screen of death thing!

You probably need to grab the latest start.elf, loader.bin and bootcode.bin from

https://github.com/raspberrypi/firmware/tree/master/boot

I had to do that last weekend when I grabbed the latest ROM.

In my config file I have

kernel=RO768.img

# Generic RISCOS options
framebuffer_ignore_alpha=1
framebuffer_align=0x100000
disable_overscan=1

# Set up the SD Card speed correctly
init_emmc_clock=100000000

Leo, thank you so much! That’s cracked it!

PiRODock lives!

I’m currently using it with an external keyboard and mouse, but it is running off the lapdock’s internal battery. I’m waiting for a MicroUSB to USB adaptor, which will hopefully enable the dock’s keyboard and mouse (and internal 2-port hub) to work, thus making it fully portable! Well, except for internet… anyone want to write a wireless driver?! ;-)

A picture of it running is here . And the gubbins of it is pictured here

PiRODock lives!

Looking good! Glad to hear you’ve gotten it up and running.

I’ve built a RPi ROM from the 5th August. The actual resolution is set to 1360×768, as that seems to be the correct one (It doesn’t display correctly with 1366).

I am hoping to run my Pi at IRUG (Invicta – Kent RO User group.), however the only available monitor that it would plug in is a widescreen PAL TV. Ultimately I intend to get a lapdock, but would it be a major inconvenience to create a 1024 × 576 (or similar) version, for PAL TV out? And if it wouldn’t, could I request one please?

I was wondering if I’d get any more requests!

would it be a major inconvenience to create a 1024 × 576

I’ve not tested any of these but I’ve uploaded the following images

1024×576 = http://www.mybigideas.co.uk/files/RPiRO576.zip

1280×720 = http://www.mybigideas.co.uk/files/RPiRO720.zip

1280×1024 = http://www.mybigideas.co.uk/files/RPiRO1024.zip

1600×1200 = http://www.mybigideas.co.uk/files/RPiRO1200.zip

That’s great! Chris Hall and I are going to check out a projector system next week, in advance of a Raspberry Jam. Thanks :-)

I presume that the config.txt file needs to change as well – using the ‘720’ rom at present I get RISC OS displaying at 1280×720, but the GPU outputting that stretched to 1920×1080 (so a projector would see 1080p). Yes – set hdmi_mode to 4 and I get 1280×720 at 60Hz (but I think it may be dependent on which mode the GPU adopts after talking to the monitor, CEA or DMT). The concept that there are two stages – RISC OS to GPU and GPU to monitor – is a new one for RISC OS. This makes the existing monitor configure plug in look anomalous?

I presume that the config.txt file needs to change as well –

Probably. If going over HDMI then the GPU will try and match the displays native resolution, if its a VGA projector then you’ll be needing a HDMI to VGA adaptor, which may cause problems.

There’s a list of hdmi modes you can set in the config.txt at http://elinux.org/RPi_config.txt to forcibly set the display output mode, which is probably what you want to do (At the Cambridge Raspberry Jam we had two HDMI to VGA adaptors, and only one gave a working output, so best to check before hand!)

it may be dependent on which mode the GPU adopts after talking to the monitor, CEA or DMT

You can use the hdmi_group option to force it to select CEA or DMT

The concept that there are two stages – RISC OS to GPU and GPU to monitor – is a new one for RISC OS. This makes the existing monitor configure plug in look anomalous?

Getting RISC OS to talk to the GPU is still being worked on I believe. So at some stage it should be possible to correctly configure the video output from inside RISCOS.

HDMI to VGA adaptor

Thanks for the advice. I’m informed that the system takes both inputs. We’ll see how it goes. I don’t have an adapter.

That is why I will be awating your call on Tuesday Trevor – I may need to source a converter!

I’ve ordered another HDMI to VGA adaptor (As mine would only display output until something like the Display module loaded) which will hopefully perform better on the RPi.

Warning: HDMI to VGA adaptors that are unpowered will only display at very low resolution e.g 640×480 & 800 × 600. Add a powered repeater and most of them will do 1920×1080!
Even then many will only do certain resolutions.
One adaptor quoted 180mA power usage (Well above the 50mA HDMI spec) I don’t know if you can damage an R-Pi drawing to much power!

We just happen to sell a powered HDMI to VGA adaptor but they are not cheap :-(

The final piece in the jigsaw arrived – a DeLock microUSB female to USB A male adaptor. And I can confirm that everything works as well as can be expected!

So the full kit is:
An Atrix Lapdock
A micro HDMI female to HDMI male adaptor
A (Blackberry-branded, in my case) microUSB female to 2 x MicroUSB male
A DeLock microUSB female to USB A male adaptor
And a Raspberry Pi obviously!

With a little bit of shaving rubber off the adaptors, they all fit together nicely to power the RPi, display RISC OS on the screen, and utilise the Lapdock’s inbuilt keyboard and mouse. And internal USB ports!

If you are going to attempt to make one yourself, the thing to remember is to split the data cable on the Blackberry microUSB splitter (they are marked as “data” and “charge”), and cut the red +5v cable, before taping back up.

Oh, and you need to map the second mouse button to “menu” – I used a little module called KeyMapper to do this.

Big thanks to Leo for the custom ROM displaying 1360 × 768, without which, it would be rubbish and useless!

I’m actually typing this on my PiRODock – the new, but ugly, RISC OS portable!

Many thanks for the 1280×720 ROM image – with the following in config.txt:

hdmi_group=1
#1-4:  720p60Hz = 1280x720
#1-19: 720p50Hz = 1280x720
#1-17: 576p50Hz = 1024x576
#2-35: 1280x1024 60Hz
#2-51: 1600x1200 60Hz
hdmi_mode=4
#hdmi_drive reqd for group 1
hdmi_drive=2
#arm_freq=800
disable_overscan=1
framebuffer_ignore_alpha=1
framebuffer_align=0x100000
init_emmc_clock=100000000
kernel=rpiro720.img

My Lapdock has arrived :) , but I expect the cables to take weeks :( .

I tested the 576 image and it seems to work fine. Thanks.

Does anybody know what happened to that module that NC OS used so that when you pressed the two buttons next to the trackball (select and adjust) on the IR keyboard you got menu?

If it was part of NC OS, in theory, it should be kicking around in the sources somewhere?

Any ideas?