> I was originally planning to take my $3 keyboard and cut it up into 4 switch rows and rewire it, and plug the USB into into my RPi... done, I have the SW to compile on the rpi already to go :) The "rollover" is only 4 and it would probably be nice to have more, but a lot of the mechanical KB have "n rollover" if they are used with PS2. So I am going to see if I can set up one of the RPi serial lines to deal with that. hello Len, I had deep^ly looked at you excellent work with this keyboard midi controller when you mentioned it on the list. Excellent work ! > >> After searching for information, nothing revelant was found, except a experimental python script to read gpio and using the mididings library to output messages. > > What kind of a keyboard for what use? If you mean a piano style keyboard then latency becomes more important. I would suggest script may not be the best way to go. c or c++ makes more sense. oops, yes my question is about Piano/Organ keyboards. C programming is the intended way > >> Is there a existing project which would scan rows/colums of a keyboard from the designated(configured) gpios, and throw midi message to an alsa midi port ? > > My next phase for midikb (the SW I used above) is to add ALSA MIDI to the mix. However, have you looked at: > http://ucapps.de/ > http://wiki.midibox.org/ > They do not use the RPi mostly because this project has been around longer than the RPi. Let me explain why I try to know if this is possible : The raspberry board is intended to run a single organ/piano application (jackd is not mandatory here) as a standalone board. In order to keep the keyboard size and electronics to a minimum, using the onboard gpios for keyboard scanning would be wonderfull. Be aware that for now the raspberry is running perfectly with a cheap USB MIDI keyboard. > >> Would such a program better be a kernel module or a userland program ? > > Making a kernel module/patch is at another level of programming which i may attempt some day by starting with the snd-serial-u16550 or mpu401 code. This is why it could be a good training for me aswell. Using the snd-serial-u16550 and adding the scanning code was part of the plan, and I was wondering if anyone tried it before. It looks like nobody did ;) > Placement of diodes on switches is important to allow chording (more than one switch at a time). The keyboards I have (from unrepaired pianos/organs) have all the diode matrix in place. Ready to use. > After you have this input you will want to do some debounce. Then you have a list of keys that are down. What you do with them from there is up to you, some kind of a lookup table to convert from key to MIDI note... 8 address by 8 data lines will give you 64 keys. Thats 16 GPIO lines for no external circuitry. The RPi is not overflowing with gpio that are not multipurpose... so maybe try this: > http://pi.gadgetoid.com/article/building-the-pico-piduino this is only a lightweight arduino way to do the thing, I would not learn anything new using this µp, and I love to learn new things. Would it be that nobody tried it before because it is so easy to do with an external µp ? > or this: > http://www.hardkernel.com/main/products/prdt_info.php?g_code=G135390529643 would better use multiplexers on the GPIOs > > Not very comprehensive for sure. However, that is what DIY is all about, Take the bits, do research, make something new. indeed, your answers are part of the quest. Raphaël _______________________________________________ Linux-audio-user mailing list Linux-audio-user@xxxxxxxxxxxxxxxxxxxx http://lists.linuxaudio.org/listinfo/linux-audio-user
