This is starting to seem pretty hard, i'm ok with "only" using CCs instead od nrpn and the issue with having to press twice for effects is not really too nanoying, i barely enable/disable stuff, but i'd like to use the screen to retrieve info from the kemper, i've been researching for a while, no luck so far
Yes, it can be heavy-going! Take a look at this thread:
1) If i use the controller to switch between rigs in performance mode, go performance up/down, enable the tuner and turn effects on/off, what's the advantage of using nrpn agains normal CCs as i was using?
no advantage, i dont think, just use whatever is easier and does the job
2) My code was not acting properly since the beggining, it wasn't "remembering" the effect status, so some times to turn effects on/off i have to press the button twice (let's say delay is off, i press once, the arduino sends off CC, so it does nothing, and then i have to press it again to turn it on) is there a workaround for that? It's not a big issue for me since i don't play live or anything, but it would be cool to get it fixed.
unless you have two-way communication to read the state of the Kemper (which makes it much more complex) you need to assume the state of effects when selecting a new rig (program/slot change) and start with your arduino in that assumed/reset state
3) Any idea how could i make the screen to show kemper info? Mostly performance in one row and rig name on the second one, i dont need too much stuff.
Thanks!
you need to send a system exclusive message to retrieve the information which will be returned as another sysex message which you need to de-code and convert it into text. This is next-level midi stuff so make sure youre happy with the first two items first. Alternatively (and much easier) you could "assume" the names-per-bank/slot in the arduino and present these on the screen.
I already tried with 31250 but the kemper still freezed, i have no idea why
Have you got some kind of midi monitor device? Worth checking if there is any unwanted midi data or other noise getting sent that is not required. or perhaps it is sending/getting incomplete midi messages?
Or maybe (as i have had in the past) the ardiuno is stalling and not sending out a steady/even flow of midi data. I found that constantly updating the screen on the arduino LCD takes a lot of processing-power that affects midi transmission and better to update the display only when needed, ie a change of data. Therefore the priority is prioritising midi data flow rather than a visual.
here's a nice bit of bedtime reading on the subject:
This is the code i'm using for testing (as i said i barely have programming knowledge, so i'm figuring out stuff by myself).
I also tried 115200 as baud rate.
The standard for midi (not USB midi) is a baud rate of 31250 so that must be adhered to
how do you know that MSB=80 is going to be +3dB? )
this is the bit that i initially figured out with trial-and-error rather than an educated approach.
The "proper way" would be to find the range of that parameter, in this case -6db to +6db where 0dB is mid-way, therefore a full-scale range of 12
divide the NRPN range 16383 into 12 = 1365 per dB step (could be taken as smaller steps if you want 0.1dB resolution) then to get the values
1365 x 6 = 8192 (0dB setting) then divide by 128 for the MSB value which = 64 ( i've lost the LSB value somewhere there...)
Yea, i managed to make it work, it's just i had to use pins 2 and 3 and they were already used by the controller, but the sxreen is working now (at least showing basic text).
Now i gotta figure out how to send/receive nrpn, i worked on it 3/4 hours yesterday and i still don't even know how to add them to my code (if i have to use "MIDI.sendControlChange" (i've read that nrpn is basically 4 CCs) and send the 4 CCs at the same time, or i gotta use MidiUSB.sendMIDI or send(SystemExclusive or what))
I know the theory, you gotta check what you want to send, and calculate MBR and LSB, it's just i have no clue how to implement it on my code, i can't find any code example or anything anywhere, no idea what functions i gotta add or anything, kinda weird i couldn't find any example of a proper code here in the forum.
I find explanations on what NRPNs are, but nothing on how to implement it or anything.
for the Kemper, just send four CC messages in your arduino (often easier than attempting to implement NRPN which i dont see much of in the arduino midi-libraries. You can find the values in the Kemper midi-spec without having to calculate the actual NRPN, (which if i recall from memory is MSB*128 + LSB.
I have an "older" list that covers most NRPN values, page 3, here https://greendog.co.uk/kemper/kemper-midi-data.pdf You can get the MSB and the LSB. Just need to work out the parameter value (which i cant comment on) other than the range is a 14-bit value (so 127 midi is 16383, and half-way midi 64 is
8192)
Apologies if i'm telling you stuff you already know! 
little example of NRPN conttrol
Set rig-volume to +3dB
CC 99 = 4, CC 98 = 1, CC 6 = 80, CC 38 = 0
This equates as-
NRPN Parameter address: MSB = 4, LSB = 1 (the Rig volume parameter)
NRPN Parameter value: MSB = 80, LSB = 0 (a value of +3dB) this could also be a different value between -6dB to +6dB (or whatever the full-range of this parameter is
additionally, you may want this midi data too:
Reset rig-volume to +0dB
CC 99 = 4, CC 98 = 1, CC 6 = 64, CC 38 = 0
After several tests, the same thing happened in browsing mode, the KPA buttons, LEDs and display all crashed and recovered after powering off and rebooting
Have you tried your midicaptain in one of the "standard" or super modes? Perhaps try an older firmware to elminate the problem could be with the midi-captian KPP custom firmware
Just got the board and a cheap 16x2 screen, i'm doing some testing.
So far i can't even make the screen work within the controller (not even using a simple "hello world" print code) it lights but there are no letters, just black squares.
The weird thing is that when i tried it without the rest of the cables it worked, and if i try it with the old arduino uno board it also works, i'm trying to figure out what could be the problem, but i have no idea so far...
I didn't even start with nprn or anything yet.
make sure you are addressing the screen correctly and your code is configured for that type (ie 16x2) You may find that your code needs a tweak depending what outputs you are using, whether you are using an IC2 between the arduino and screen and a few other factors. Go search several LCD-to-arduino codes examples and see how they vary.
its very satisfying to have built your own midi controller and certainily allows you to do exactly what you want. But it can come at the cost of mental-stress and, obviously the time-cost. After all the controller i have made and used (and gigged with) i have chosen to use an off-the-shelf device for my Kemper player at present.
Just wondering, that screen is pretty interesting, any idea if it would be doable via USB?
I'm not sure if the kemper will send info (and if it's gotta be MIDI or what)
with a bit of tinkering, you can retrieve data and parameters from the Kemper- another project:
Just bought an Arduino Leonardo, delivered tomorrow apparently, so i'll try to make it work by replacing the Uno i'm using currently and using the USBMIDI library, i'll have to do some changes in the code, i'll let you know if i manage to make it work
cool. keep us posted. thanks Erikcb
Here's my most recent Arduino midi controller though it relied on a USB to midi interface/cable rather than directly USB-to-USB
Have you tried 23 for Modulation Crossover?
According to that list Mix is at 4, Volume at 6, and Ducking at 53.
Thank you- found it. Appreciated.
Can you confirm if the issue with the player's chorus (pre v11 OS) is a control issue, ie not accessible via rig-manager or if its an OS problem with the player's coding. thanks. Could save me some time trying to work out for myself.
Please can someone tell me the NRPN values for:
Chorus (modulation), Crossover, mix, ducking and volume
i wish to address these parameters via midi but dont see them in the midi documentation.
All i can find are these few:
The nature of an Arduino board/project is writing code for the board, so reflashing an Arduino board is almost a trivial task when working with such boards.
Agree. But like many things, if you've never done it before it can appear daunting. It's installing and using lesser-known flashing-software to do the operation that raises my concerns. Certainly, coding midi operations becomes more comfortable with experience.
I'm trying to use the arduino to send MIDI CCs via USB, it's a DIY controller i made that i was using via MIDI cable, i'll have to do some research and see if i'm capable of making it work just via usb, that way i can use only one cable for the controller instead of USB + MIDI cables.
Thanks for the info!
Let us know how you get on.
Be great if the Kemper recognised an Arduino as a midi device (a bit like a PC/Mac can) without the need to reflash the arduino-firmware
follow up....
This is a known issue to be addressed in a future OS update.
running OS 10.9.8 and it seems to me the vintage chorus is broken.
the crossover, mix and ducking parameters have no effect whatsoever.
i will file a bug report with support.
Can anyone else confirm this too?
thanks
very intriguing!!
How easy was it to install your code into the device?
Could you confirm the procedure required to do so.
Maybe a little video-demo would be nice too.
I didn't use an Arduino but a Raspberry Pi Pico.
Perhaps you can adapt something from my code.
Here is my diy project: Custom Firmware for PaintAuido MIDI Captain MINI 6
So you have reverse engineered the midi-captain? ie, you managed to use the hardware with your completely your own code?
If so, very interesting!
Thanks for this. Do you mean re flashing the arduino or the Player?
it involved re-flashing the arduino firmware. I've never done that kind of thing before so cant comment further. Would be a great solution for the DIY enthusiast,
thanks for the update, AppleTreeChen .
Will wait until i've finished this week's gigs first.
I assume we still have supermode and geek mode available?
