Adding buttons which trigger notes + mute/transform

[SupahFly]

Hello :) I haven't built my midibox sid yet but I would very much like to add buttons which, when pressed trigger notes, i.e essentially a keyboard but I would like to use buttons instead of keys.

I've seen a few boxes here which have incorporated existing keyboards but I am wondering what the best approach would be to implement this using just some standard buttons?

Another feature I would like to add to my midibox is to mute the synth at the press of a button. I guess the easiest approach would be to cut off the signal before it reaches the outputs but I have no idea how this would be implemented in practise. Or can I do it through software? What I want to achieve is essentially a "transforming" sound which can be produced by cutting the sound on/off quickly. (e.g. Older DJ mixers usually have transform switches).

Any guidance on these two features would be greatly appreciated!

[TK.]

Hi,

adding the button functions for playing MIDI notes is easy. I can give you the code once you've build the hardware and you are able to try it out (usually it will have one or two bugs on the first try, so be prepared for some time consuming beta testing sessions! ;)

There is only one requirement to make the SW support as simple as possible: add the additional buttons to dedicated shift registers, don't mix it with other shift registers which are used for existing functions.

Mute: no way to do this via software, as it would require to fade out/in the volume with high resolution to avoid the "click", but the SID volume can only be controlled with 4bit, which isn't sufficient. In distance, you will hear a click on each volume level change since the DC level changes as well - this "imperfection" was used to output audio samples in the past ;)

Best Regards, Thorsten.

[SupahFly]

Thanks so much Thorsten! Will there be any noticeable latency using this method? My plan was to add 16 buttons in a 4x4 grid which the user can play.

Would it similarly be easy to implement pitch bend (I assume this is supported via midi) at the touch of a button?

Oh by the way, what language is the software written in?

[TK.]

The firmware is written in assembly language, therefore changes are error prone (especially if you haven't programmed on the firmware for more than 2 years...)

Will there be any noticeable latency using this method?

no

Would it similarly be easy to implement pitch bend (I assume this is supported via midi) at the touch of a button?

you could add a pitchwheel to an analog input so that it's available as knob function (and which can be routed to the PitchBender "knob" function).

But what do you mean with "at the touch of a button"?

Best Regards, Thorsten.

[SupahFly]

thanks again Thorsten. I guess now would be a good time to finally learn assembler then :)

My idea was to use a joystick with, say 4 directions (digital), each direction being mapped to a different function. I thought up and down could be mapped to a pitch bend but since it is digital I guess this would either have to be some increasing pitch bend depending on how long a direction is pressed - but I don't know if that's possible. I think a joystick could make the synth a really interesting performance tool :)

[TK.]

You won't like such a "digital joystick function", it's hard to use since you won't be able to control the speed properly (e.g. slow or fast fades)

Just connect an analog joystick (with two pots) to two free analog inputs, the pot values are available as free assignable knob functions, and also in the modulation matrix (means: you can apply mathematical operations, e.g. for inversion, multiplication, digital stuff like XOR, AND, etc...) -> very useful

Best Regards, Thorsten.

[SupahFly]

hmm I guess you're right - I'm just brainstorming a little. How about buttons for changing the octave?

I'm going to stop now I'm just excited and can't wait for my parts to arrive :)