Making MIDIIO128 into MIDIIN256? or MIDIOUT256?

[jimhenry]

For organ projects where one needs to deal with a lot of inputs only or a lot of outputs only, would it make sense to take MIDIIO128 as a starting point and create an application that does just input or just output? 

I am trying to make a guess as to why there is a 128 input or output limit.  Is it the practical limit on the length of the serial shift chain?  The limit of available memory for the configuration tables?  A perceived limit because of 128 MIDI values?  Just arbitrary based on the needs of the project that gave rise to MIDIIO128?

What I am thinking is that both of the serial pins could be used for input or for output and one of the two configuration tables replaced by a second input or output table to service the second serial shift chain.

Is this sensible?  Or should I just use 2 linked cores for every 256 inputs or outputs and not worry about trying to squeeze more into an input only or output only configuration?

What I am think of initially is just an "extension cord" to take about 500 wires from an organ console, convert them to MIDI, run them to the organ chamber via MIDI over fiber optics, and then convert them back to 500 wires.  Ultimately I might enhance the deserialization end to convert the MIDI In to the 1000 or so wires needed for the pipes.

[smashtv]

What I am think of initially is just an "extension cord" to take about 500 wires from an organ console, convert them to MIDI, run them to the organ chamber via MIDI over fiber optics, and then convert them back to 500 wires.

Wow change "fiber optics" above to "RS-485 over cat5 cable" and you and I will be on the same brainwave (sorry for you!)  ;)

This MIDI extension cable is high on my tinker time list, I need it for another design I have in the works....

Best

Smash

[Tibia]

Really like the possibility of RS-485, having used it for a few process control schemes (using the Modbus ANSI protocol).

Originally looked at a diy midi to fiber converter for my Miditzer project, but the HP transmitter and receiver are from an earlier standard.  Jim suggested the possibility of redesigning the circuit(s) for the newer ST termination standard.

Now to find a good diy midi to RS-485 converter project...  8)

Bob

[TK.]

Hi Jim,

I am trying to make a guess as to why there is a 128 input or output limit.  Is it the practical limit on the length of the serial shift chain?  The limit of available memory for the configuration tables?  A perceived limit because of 128 MIDI values?  Just arbitrary based on the needs of the project that gave rise to MIDIIO128?

128 is just a number where I can say, that it works perfectly for most MIOS applications, therefore I set this limit. It's a compromise between CPU load, memory consumption, and electrical parameters (a longer chain - or more DIN/DOUT modules in parallel would require a slower clock rate)

However, there are thousands of different, application specific possibilities, but all of them would require a dedicated software driver and different circuits/schematics - I cannot support this, it's too complicated to specify all the requirements and possible variations...

Therefore I normaly recomment the use of an additional core

Best Regards, Thorsten.