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1  Using Arduino / Audio / Re: Translate MIDI notes to CC for Kaossilator Pro - Possible? on: January 06, 2014, 05:26:53 pm
Max is just a visual scripting language, correct me if I'm wrong here, based off of C++ but not directly compatible.

You can use Max to communicate with Arduino, but code isn't compatible (that I know of) between the two. If there is an automatic way to convert max code for Arduino, then please let me know!

I personally use Max when I'm prototyping Midi stuff; yes, it may seem odd as it's seemingly incompatible code, but I design my whole system in Max to get the entire concept down before writing code for Arduino. It's much quicker for me to work with hardware by visually programming and not having to upload and wait a minute between changes in code, etc.

When I have my rough draft written out in Max, it's quite easy and quick for me to translate everything manually to Arduino, rather than only building it on the Arduino alone.
2  Using Arduino / Audio / Re: Translate MIDI notes to CC for Kaossilator Pro - Possible? on: January 05, 2014, 11:34:44 pm
I just whipped this up for you (attachment). Let me know if you have any questions.

Just open max and paste the code inside.

This code will let you play with sending midi notes as a controller value (via the keyboard at the right), and you can set the value with the number box.
The other stuff in the middle (the big cluster of stuff) will monitor what comes in, and you can send custom messages out from here.
3  Using Arduino / Audio / Re: Translate MIDI notes to CC for Kaossilator Pro - Possible? on: January 05, 2014, 11:00:27 pm
I can agree with Deseipel. If you have Max MSP, it may help with quickly prototyping the mapping you wish to do and quickly get the codes you want (I prototype everything midi through Max). JM2C
4  Using Arduino / Audio / Re: Pickup signal router on: January 05, 2014, 10:28:28 pm
5  Using Arduino / Audio / Re: Pickup signal router on: January 02, 2014, 07:20:41 pm
Hi DVDdoug, thanks for replying.

I suppose I should have been a little more specific. Mainly, I'm just going to be routing the pickups for different switching combinations that can be recalled as a preset. By doing this all digitally I could route a coil A of the neck humbucker into coil A of the bridge humbucker, as was all paralleling the signal from coil A of the neck with coil B of the bridge in reverse polarity.

Yes, my example is a bit extreme in the sense of common switching, but it's just to show the flexibilty that I'm aiming for.

My main concerns would be size, cost, and ability to play well with a soldering iron adc and dac combo, and the code that would be associated with this i.e. would I just read the signal like a regular analongRead, use the int returned and send it to the output that I want? That would give me the routing options I need, but how would i reverse the signals polarity in code? Would I just use a regular int and invert the number? For adjusting the volume (not gain, just cutting the volume) could I just use basic math like multiplication and division? Say, take input 1, divide by -0.5, send it to output 2, thereby sending out the opposite phase of the input signal at half volume?

In all honesty, I'm much better at coding than I am with actual analog hardware -I don't have to worry about frying anything with software smiley
6  Using Arduino / Audio / Pickup signal router on: January 01, 2014, 10:57:30 pm

My goal is to use an arduino to route up to 8 audio signals (signal in and out of the guitar itself and up to 6 pickups)
I've looked into crosspoint switches, relays, optoisolators, and fets to switch analog audio, but they all required too many external components and I'm limited on space as this will be mounted in a guitar. I'd prefer to not route out the body any more than need be.

I was thinking about doing an ADC/DAC combo, well 8 of each I suppose, and digitally route the audio, but I would like anyone to share any advice they could give on this. Would this be too ram intensive for an arduino to handle? As it would ideally use 16 bit adc/dacs and the arduino can handle 16 bit numbers, would there be quite a bit of latency that I'd need to take into account?

It's sort of like a DSP thing, although I'm not going to be doing effects, just volume of signal, phase (polarity) inversion, and sending input x to output y.

Things I'm looking to get out of this post:
-good adc/dacs to use, maybe multi channel ones? I've looked through quite a few, but my knowledge is limited when it comes to these kinds of chips.
-advice on how to code this perhaps?
-input, etc.?

7  Using Arduino / LEDs and Multiplexing / Re: IC Chip Selector for SPI's CS on: September 14, 2013, 05:12:14 pm
Cool! Thanks for that, it definitely seems promising.

One question regarding a shift register as an output:
If I were to have say, 5 of these in a line (hypothetically) and I were to send the first one a string of 5 values, does the first chip take the first value and pass the other 4, then #2 take the 2nd value and pass the rest, 3 take 3 pass the rest, etc. ? Similar to the functionality of the WS2811 led driver in those addressable led strips?

If so, then I will most likely be going this route. Also, 35 ma is plenty; the relays take a max of 20-25, but I just prefer to have some headroom and just said 40 as it is the IO ma rating for the 328 chips in Arduinos.

EDIT: upon more research, I realized that once chip one is full, it will start shifting them further down the line, so it doesn't exactly take the first, pass the rest, therefore I would have to write the last value first, rather then first to last, which isn't a big deal honestly. Thanks!
8  Using Arduino / LEDs and Multiplexing / IC Chip Selector for SPI's CS on: September 14, 2013, 02:13:53 pm

I am looking for (but can't seem to find anything relative) to a chip that I can send a value, and it will have a series of outputs that it will set as high or low.
My goal is to hopefully use a chip that will be accessed by maybe a few pins in hopes to limit using many pins just to control high or low chip selects on multiple other components, and must be able to source and sink current of up to 40 ma as I am using the chip select type interface for controlling monostable (one coil, latching) relays.
It will be used to select a digipot to listen to the SPI line, or used to toggle a relay).

I had considered using multiplexers, as I have quite a few on hand, only it is overkill for what I need them for (I just need it to set a pin either 5v or gnd, not in between nor for data I/O), and it would require a minimum of 3 pins for addy selection of 8 mux'd I/O's. Space is a big factor, so I can't have two mux's just to get 16 more pins, whereas I would like to use a single 16 pin chip and get maybe 12 (that would be sufficient for what I'm doing). I also assume the interface could be as simple as the SPI interface at CS, MOSI, SCK, 5V, and GND. In contrast, instead of using 2 8 I/O Mux's that would require 6 pins, I would like to be able to do it at 1 10+ I/O thingamabob that would require using one CS pin (I am already using the SPI interface for other do-dads too).

Anyone know of a chip that would basically be a dead simple mux suitable for 40 ma/pin source or sink?

EDIT: basically a Max7301, but with not as many IO pins and that can transfer 40 ma of power. I suppose I'm looking for an SPI controlled GPIO expander. Anyone have any suggestions?
I need atleast 10 pins of expansion (preferably 12) so that should be able to fit within a DIP-16 package, right?
9  Using Arduino / Audio / Re: Wireless guitar on: August 29, 2013, 07:45:46 pm
Hey Far-seeker,

Almost a year later (correct me if I'm wrong, but I figured it would be better to revive this thread of mine rather then start a new one and have to back-reference to this one) I finally got around to working with stuff again. The issue I was having with the DC blocking out the sound was that I need decoupling capacitors on the ground side too; but I got it to work!

So it would be like the attached schematic: Guitar Power Over Audio.jpg (it's ugly, I know).

Would I need to get caps rated for at least 9v in this case, or would it not matter as it's being used only to block power, not absorb it?
Still a little confused on the Arduino and power supply side; would/should I use an inductor or diodes to filter out the AC signal, or will it not matter?
Don't want to damage the Arduino, and I may need to filter the 9v anyway otherwise it could bleed into the circuitry that will be processing the guitar's signal.

10  Using Arduino / General Electronics / Re: Bi-directional Midi fun on: April 02, 2013, 06:03:00 pm
Thanks for a fast response guys!

I verified that a 5 pin midi cable is only 5 conductors, and I believe the middle conductor (2) is the bare wire that touches the foil shield on the inside of the cable.
5 wires plus a 6th bare wire that touches the foil would have been nice (the bare wire would connect to the plug shell on either end of the cable).

In the schematic I linked above, pin 4 is a hot signal, and pin 5 is switched to ground at the Midi message's values.
If I were to combine in and out in a single cable, I think I can do 3 pin Midi instead of 4. Basically, making in and out share a 5v line, and the two message lines will switch a transistor. Then I have two more pins for + and - power.

Seem doable? Or am I missing something?


I think I figured it out. On the master (processor) pin 1 add: 5v or 9v to power other stuff in the slave (pedal), pin 2 remain: ground, pin 3 add: Midi out, pin 4 remain: Midi in 5v line that can share with the 5v line for Midi out on the slave, pin 5 remain: Midi out (signal).
That way it is still backwards compatible with regular two cable midi devices. I was planning to add this to the Midi in on the master, and Midi out on the slave, so I don't have to drill more holes.

In the first schematic I linked to:
Could pin 4 on both the Midi in and out ports on the same device, be connected together? It would still be the 5v+ -> 220Ω(out port) -> 220Ω(in port) -> Midi goodies; instead of the 5v from the other device plugged into this one, couldn't the power just be ported accross both pin 4's without damaging it? What is the point of isolating the 5v supplies between two devices like this?
11  Using Arduino / General Electronics / Bi-directional Midi fun on: April 01, 2013, 11:38:07 pm

I just picked up an old A.R.T. X-15 Midi controller and an SGX2000E (already got an awesome Savatage tone out of it in the two days I've had it!), and of course, I must modify it.
The Midi controller is a pedalboard style, and it has Midi in, out, and thru. Also, it has a power port. (duh)

Now, my goal is to fit Midi in, out, and power onto a regular 5 pin midi cable so I can wire the X-15 to the processor with one wire, instead of 3. I don't want to use a 7 pin cable, otherwise I will need backups of those, whereas all my other Midi stuff uses 5 pin cables.

I was looking at this general schematic for Midi, and I noticed that there is a (source?) and a (sink?) for the input, and the output looks like a single line and a 5v+ output.
I'm assuming it's sort of a remote switching mechanism?
Could someone tell me if I could wire the 5 pin cord to be setup as Midi input, output, + and - power, summing up to 4 pins used, then having an Arduino on either end to do the "switching" that I stated above, whilst providing power to the pedalboard? Or is the Midi input a Clock & Data style setup? If its the first, then I suppose I'm basically doing uart at the Midi baud-rate.

One other question, the 5 pin midi cord, is it actually 5 conductors, or is it 6 (5 isolated wires and a bare wire touching the shielded foil) ?
I would assume it is the latter, and that would be why a lot of devices have the ground lift if their chassis is made of metal. But you know what they say when you assume.. smiley

12  Using Arduino / General Electronics / Re: NRF24L01+ antenna connected to AC audio line on: February 04, 2013, 02:13:48 am
Thanks for the input.

I considered running another cable alongside the guitar's cable, which would be easily doable. However, if said cable ever crapped out while playing live, the most common cable on hand is a mono 1/4 cable. I suppose building my own cable would be the simplest.

I could do the fm thing, as long as its above 20khz honestly. 2.4ghz was just more readily available.
Given the circumstance (guitar cables defeat 1+ ghz), if I used a stereo guitar cable, I could have power over the cable instead of only onboard battery power, but could I use that as a two way communication line as well? For instance, on the left channel (tip) would be audio, on the right channel (ring) would be power to the arduino, and communication to and from the pedalboard.

As long as it wouldn't be heard or interfere with the audio signal, would provide reliable power and communication, would this be doable without building a proprietary cable?
It would be nice to be backwards compatible with a regular mono 1/4" cable when I choose to play it like a regular guitar, so I would be limited to using a 1/4" mono or stereo.
Also, I am going for a sleek look on the guitar, so having multiple ports for different scenarios is not my preference.

13  Using Arduino / General Electronics / Re: NRF24L01+ antenna connected to AC audio line on: February 01, 2013, 07:20:17 pm
Mike, thank you for answering my question.

Do you know of a better module than to use the NRF24 in this circuit?

I basically wanted a >1ghz fm communication line that wasn't going to cost me an arm and a leg, would work for a good distance(the farther the better), and would work over the guitar cable rather than through the air.
I was only thinking to use the NRF's because I have a few of them lying around, and they are really cheap in price, good distance, etc.

14  Using Arduino / General Electronics / Re: NRF24L01+ antenna connected to AC audio line on: January 31, 2013, 11:14:37 pm

I understand the NRF24 does not transmit an analog signal. A DAC/ADC combo would be necessary for that.

The attached picture shows the diagram.

In the future I plan to make a 2-way wireless guitar adapter. 2-way is necessary for guitar's and pedalboard's arduinos to communicate, while still passing the analog signal.
This would need to be backwards compatible with a regular guitar cable, and work on any guitar.

My idea for the wireless guitar thingy: (any)guitar->ADC->NRF24->air->NRF24->DAC->amp/pedals/whatever.
So with the NRF equipped guitars, it would be: arduino-->nrf24->(in parallel with guitar signal)->guitar cable->pedalboard->(splits to nrf24->arduino and guitar signal->pedals).
In this case, with the 'wireless guitar thingy', I could directly swap out the guitar cable with it.

I cannot have the nrf24's go through the air, it must be through the guitar cable. (will have no interference if I turn and am between the two nrf24s, physical objects in between the two will not affect performance, better asthetics, not having a 4 inch antenna sticking out of my guitar and having 2 of them when I go full wireless, etc.)
Overall, its better for it to be hidden and operate on a specific line, rather than the airwaves.

Does this make sense?
If the signal goes through the guitar cable, there will not be anything in the way of the transmitted signal, and there won't be outside interference due to the cable's shielding.

Sorry for the confusion.

So, my main question: will a very very low voltage AC signal hurt the nrf24s? I would assume not, since it is well below its operating voltage (even if its AC).

15  Using Arduino / General Electronics / NRF24L01+ antenna connected to AC audio line on: January 30, 2013, 09:23:16 pm

First, I have a few of these:

My question, is I plan to put one of these in my guitar, and one in my pedalboard. So the voltage will be +/- 1VAC.
Will there be an issue with having the antenna directly attached to either of the AC wires?
Meaning, will an AC voltage that low mess up the NRF24L01+?

I have considered using diodes to prevent flow to the antenna, but wouldn't that make it so neither chip could listen, only speak?

I think the audio signal would be fine, considering the nordic chip communicates at 2.4 ghz and would be far out of the range of human hearing. I will also put a filter for above 1ghz to save my pedalboard and amp.

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