Ego Sys, Miditerminal 4140 Driver

Ego Sys, Miditerminal 4140 Driver

[Matthias König]

Hello alsa-devel,

I own a Miditerminal 4140 by ESI, which is a 4 In 4 Out Midi interface
with SMPTE timecode generation for the parallel port. Since I want
this device to work under Linux, I've been working on a driver for
ALSA.
It seems that I have some success now. At least I can receive and
transmit Midi bytes on all 4 In/Out ports. Maybe someone with more
experience in driver development could take a look at the driver?
A preliminary version is available from 
www.phasorlab.de/alsa/mts64.tar.bz2
Any comments and critics would be highly appreciated.

There is still some work to do, the SMPTE timecode generation will
need some kind of control for start/stop of timecode generation and
setting the time (timecode generation is done by hardware). I'm not
yet sure how to do this; can this be done by ALSA control elements
or do I have to create a hwdep device, which would use ioctl?
Again, suggestions would be welcome.

Regards,
Matthias


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Re: Ego Sys, Miditerminal 4140 Driver

[Clemens Ladisch]

Matthias K??nig wrote:
> There is still some work to do, the SMPTE timecode generation will
> need some kind of control for start/stop of timecode generation and
> setting the time (timecode generation is done by hardware). I'm not
> yet sure how to do this; can this be done by ALSA control elements
> or do I have to create a hwdep device, which would use ioctl?

Most devices implement this as a separate control MIDI port for vendor-
specific SysEx messages, where "implements" means that the hardware does
it this way.


HTH
Clemens


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Re: Ego Sys, Miditerminal 4140 Driver

[Matthias Koenig]

Hi Clemens,

Clemens Ladisch <clemens@ladisch.de> writes:
> Matthias K??nig wrote:
>> There is still some work to do, the SMPTE timecode generation will
>> need some kind of control for start/stop of timecode generation and
>> setting the time (timecode generation is done by hardware). I'm not
>> yet sure how to do this; can this be done by ALSA control elements
>> or do I have to create a hwdep device, which would use ioctl?
>
> Most devices implement this as a separate control MIDI port for vendor-
> specific SysEx messages, where "implements" means that the hardware does
> it this way.

Thanks for this hint. The Windows driver of my device uses a dispatch control
routine (the analogon to ioctl) for this purpose. So I thought this should
be done evtl. by a hwdep device.
The separate Midiport will be more flexible, however in this case the driver 
will have to parse the Midi message, because the hardware is controlled by 
other means.

Regards,
Matthias


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Re: Ego Sys, Miditerminal 4140 Driver

[Clemens Ladisch]

Matthias Koenig wrote:
> Clemens Ladisch <clemens@ladisch.de> writes:
> > Matthias K??nig wrote:
> >> There is still some work to do, the SMPTE timecode generation will
> >> need some kind of control for start/stop of timecode generation and
> >> setting the time (timecode generation is done by hardware). I'm not
> >> yet sure how to do this; can this be done by ALSA control elements
> >> or do I have to create a hwdep device, which would use ioctl?
> >
> > Most devices implement this as a separate control MIDI port for vendor-
> > specific SysEx messages, where "implements" means that the hardware does
> > it this way.
> 
> Thanks for this hint. The Windows driver of my device uses a dispatch control
> routine (the analogon to ioctl) for this purpose. So I thought this should
> be done evtl. by a hwdep device.
> The separate Midiport will be more flexible, however in this case the driver 
> will have to parse the Midi message, because the hardware is controlled by 
> other means.

Then you probably shouldn't use a MIDI port for this.  Wrapping the
control commands into some invented MIDI SysEx doesn't make sense if
your driver just throws the wrapper away.

I think using control elements would work just fine.


HTH
Clemens


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Re: Ego Sys, Miditerminal 4140 Driver

[Matthias Koenig]

Clemens Ladisch <clemens@ladisch.de> writes:
>> The separate Midiport will be more flexible, however in this case the driver 
>> will have to parse the Midi message, because the hardware is controlled by 
>> other means.
>
> Then you probably shouldn't use a MIDI port for this.  Wrapping the
> control commands into some invented MIDI SysEx doesn't make sense if
> your driver just throws the wrapper away.

Well, it would make sense if there would be some standard to control
SMPTE via MIDI messages. 
However, I don't want to invent some random MIDI messages for this
purpose (also I'm not in the position to do that).  I did some tests 
with a wrapper port in the driver and used a MIDI Start/Continue/Stop 
and a MTC Full Frame SysEx message to set the time, which works but is 
probably not the desired thing.

> I think using control elements would work just fine.

Ok, I'll use control elements. Two questions:

What will the assigned interface for the controls be?
SNDRV_CTL_ELEM_IFACE_RAWMIDI ?

I see, that there are some standards on the names of the control elements,
however in this case this is not clear to me.
I need the following controls (with my name suggestions):

1. SMPTE switch: toggles generation of timecode
"SMPTE Playback Switch" Boolean
2-5. Setting the time
"SMPTE Time Hours"      Integer
"SMPTE Time Minutes"    Integer
"SMPTE Time Seconds"    Integer
"SMPTE Time Frames"     Integer 
6. Setting framerate
"SMPTE Fps"             Enumerated

Are these names Ok for ALSA?

Regards,
Matthias


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