Have a RIoTboard question?  Ask the expert, John McLellan

Hi John. I have Riotboard up & running using the ubuntu 11.10 distribution and have got Python IDLE working through ssh tunneling and xwindows.

I am currently learning how to use the python pyo library as I am interested in audio programming.

I have audio working fine but am having trouble with MIDI. I have an M-Audio oxygen midi keyboard which I have plugged into one of the riotboards' USB ports and the aMIDI command sees the device and can read not on off messages, controller messages etc.... but when I try to use MIDI in the pyo library I get this error:

ALSA lib seq_hw.c:457:(snd_seq_hw_open) open /dev/snd/seq failed: No such file or directory

Portmidi warning: no midi device found!

Portmidi closed.

I have tried using modprobe -a snd-seq and modprobe -a snd-MIDI but get a FATAL error message:

FATAL: Module snd_seq not found.

WARNING: Error running install command for snd_seq

Would you have any idea whats going on?

Also, if I wanted to update u-boot and compile and build and install debian as per Selsinorks' brilliant tutorials, could I do it using either just my riotboard or possibly using windows??

Thanks very much for your post and help.

All the best.

Steve.

probably the particular alsa driver you need hasn't been built. The kernel used in the ubuntu image is fairly light on drivers, things that are not absolutely necessary tend to be missing.

Rebuilding u-boot/kernel on windows alone will be almost impossible. Normally what you'd do is to setup a linux virtual machine running on top of windows and use that.

It's certainly possible to build everything on the RIoTboard, I'd suggest you find a USB hard drive, real spinning rust variety, mount it somewhere and do all your compiling on the drive rather than on eMMC or SD-card. It'll give you a good performance gain. Even so, it will take quite some time, especially the kernel.

Also don't expect miracles going to Debian and new kernel, it's quite possible I've not included all of the Alsa drivers in the defconfig, but if you're compiling it anyway, then at least you get the chance to check and add any missing things that you need.

The other option is to recompile the 3.0.35 kernel you're using with ubuntu to include any missing drivers, radiatortwo described how to go about recompiling it  here http://www.element14.com/community/message/110380/l/re-linux-where-is-uarts#110380

Keep watching the RIoTboard group - I hope to have a Debian image that you can write to an SD card (with win32diskimager or similar) fairly soon. It'll be very minimal to start, but will let you use apt-get / aptitude to install whatever you need from the main Debian repository.

probably the particular alsa driver you need hasn't been built. The kernel used in the ubuntu image is fairly light on drivers, things that are not absolutely necessary tend to be missing.

Rebuilding u-boot/kernel on windows alone will be almost impossible. Normally what you'd do is to setup a linux virtual machine running on top of windows and use that.

It's certainly possible to build everything on the RIoTboard, I'd suggest you find a USB hard drive, real spinning rust variety, mount it somewhere and do all your compiling on the drive rather than on eMMC or SD-card. It'll give you a good performance gain. Even so, it will take quite some time, especially the kernel.

Also don't expect miracles going to Debian and new kernel, it's quite possible I've not included all of the Alsa drivers in the defconfig, but if you're compiling it anyway, then at least you get the chance to check and add any missing things that you need.

The other option is to recompile the 3.0.35 kernel you're using with ubuntu to include any missing drivers, radiatortwo described how to go about recompiling it  here http://www.element14.com/community/message/110380/l/re-linux-where-is-uarts#110380

Keep watching the RIoTboard group - I hope to have a Debian image that you can write to an SD card (with win32diskimager or similar) fairly soon. It'll be very minimal to start, but will let you use apt-get / aptitude to install whatever you need from the main Debian repository.

Hi Selsinork.    Spinning rust variety lol...

OK. I'm trying to build the Linux kernel and have been successful up to the point where I want to install the modules:

make modules_install INSTALL_MOD_PATH=output..........

When I try to do this I get this error:

ln: creating symbolic link `output/lib/modules/3.15.0-rc7/source': Operation not permitted

make: *** [_modinst_] Error 1

I'm not using a mechanical HDD but a 16GB sd card .

All worked well up till now..

Any ideas what might be going wrong??

steven scutt wrote:

 

Hi Selsinork.    Spinning rust variety lol...

Yes   seriously though, a traditional hard drive is lots faster than SD

Is your SD card formatted as FAT32 by any chance ?   Non-linux filesystems like FAT won't support the creation of symbolic links.

Hi Selsinork.

Yes it is FAT32....so what would be the best type to reformat it as??

Doesn't really matter, any should do. ext2/3/4, jfs, xfs, etc.

It's normally as simple as doing mkfs.ext4 /dev/mmcblk0p1 or similar.  Although in theory you should also change the partition type to 0x83, in practise linux will detect the filesystem type without needing to do that.

If you have a spare card, use that and copy what you've currently done over.. might save you some time rebuilding everything from scratch.