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1  Using Arduino / Installation & Troubleshooting / Re: USB cable problem?? Do I need to stick to certain "types" of USB cables??? on: October 07, 2011, 09:01:55 pm
James:  Thanks for the reply... unfortunately I don't have a scope.. and I don't 100% understand your comment on a possible brown-out.  I do have a multimeter, and the voltage from the VBus to ground on the mini-USB pins using the "bad" cable on the Nano V3.0 board is 5.09 V, if that tells you anything... this is the same reading I get with the "bad" cable hooked to the Nano V2.3 board.
2  Using Arduino / Installation & Troubleshooting / Re: USB cable problem?? Do I need to stick to certain "types" of USB cables??? on: October 06, 2011, 07:15:57 pm
frank:  thanks for the input...

NEW OBSERVATIONS:  I've experiencing the "reset" behavior with the "bad" cable on an Arduino Nano v3.0 (328 chip).  However, this "bad" cable seems to work fine with my other Nano which is a v2.3 (168 chip version). 

With the v3.0 Nano, I've taken it off of my breadboard just to ensure the breadboard, nor the circuit I was testing were causing the issue... I've also just loaded a "blank" sketch to take s/w out of the equation... still resetting with this cable when connected to the hub.... but again the v3.0 works fine with the other cables.

I just don't have space in my project's enclosure to coil up 3 "long" usb cables (which are the only ones I've found with ferrites).

3  Using Arduino / Installation & Troubleshooting / Re: USB cable problem?? Do I need to stick to certain "types" of USB cables??? on: October 06, 2011, 06:15:27 pm
quite possible... or possibly even both, to an extent... I just don't know how to track it down...  but like I said, I have 2 cables that DO work with the hub... the only difference that is obvious to me is the addition of the ferrite "bead" thing on these 2 cables.

OK... after some more observation... it has to mostly be the hub... I've gotten the behavior to manifest with one of the 2 "good" cables...  and also one time I've gotten stable performance from the non-ferrite beaded cable...

but also, WHAT is the "phenomenon" I'm observing indicative of?   What's basically happening is the port on the USB hub is shutting down for a second... the light on the actual port goes out during this time...

OK, it has to be a power issue with the HUB... when I unplug the power adapter, even the bad cable starts acting good.... when I plug the power back in, the "bad" cable even stays acting good... I don't get it...

anybody got a suggestion for a small powered 4-port usb hub with forward facing ports?
4  Using Arduino / Installation & Troubleshooting / USB cable problem?? Do I need to stick to certain "types" of USB cables??? on: October 06, 2011, 04:34:38 pm
I have a short (2 ft) USB Male A to mini USB male.  Plugging it from my white iMac to an Arduino Nano, it works as expected.  If I connect this cable and Nano it to a powered USB hub (D-Link DUB-H7), the Nano resets every few seconds, and the Nano isn't recognized in the IDE.

I have 2 other longer thicker USB cables with ferrite cores that work both connected directly to the iMac AND through the hub...

I need to use the HUB to connect 2 Nanos within a project.  I know, I could just chalk this up to a bad USB cable, but the thing is... I need to buy 3 more "short" (1 - 1.5 ft) cables for a project and I need to know if I need to stick with certain types of USB cables (i.e. ones with the ferrites)... I hope not, because I haven't found short (and cheap) ones with the ferrites.

Thanks!
5  Using Arduino / Project Guidance / Re: Guitar amp foot switch MIDI IN / MIDI OUT with relays on: October 04, 2011, 04:04:00 pm
Terry:

That looks like a great board, however, due to size constraints, I have to build my own to spread out the parts within the foot-switch housing. 

Parts list I ordered:

1k 1/4W resistors for R3, R4, and R5
51k 1/4W resistors between collector and emitter
Fairchild PN2222A NPN's to switch the relays
5V relays from sparkfun
1N4004 for the "snubber" diodes (I what that was recently.... though I don't 100% understand what's really going on there)

Are there any freeware circuit simulator s/w packages (preferably for Mac) that you guys know about?  I found this website:  http://www.falstad.com/circuit/ 
It's OK, I supposed, but not entirely user friendly (or "save-able").

I bought some transistors AND a hex inverter to try with the MIDI out circuit.... I should be able to get something to work. 


I'll update when I get somewhere with this.

6  Using Arduino / Project Guidance / Re: Guitar amp foot switch MIDI IN / MIDI OUT with relays on: September 28, 2011, 10:49:41 am
Terry:  that relay module you linked to looks great!  Do you happen to have the dimensions?  I'm hoping it will fit into my housing.

Thanks!
7  Using Arduino / Project Guidance / Re: Guitar amp foot switch MIDI IN / MIDI OUT with relays on: September 26, 2011, 05:07:27 am
Thanks Terry and Mike!  I'll incorporate those ideas! 

Dumb question about the relay bit:  Why are the transistors needed?  Is it just because the Arduino I/O pins can't source enough current to turn on the relays (well THESE relays, anyway)?  How much current would it usually take considering these are 5V relays and the loads will only be 4.6 - 5.7VDC?

Thanks!

8  Using Arduino / Project Guidance / Re: Guitar amp foot switch MIDI IN / MIDI OUT with relays on: September 25, 2011, 08:13:28 pm
Thanks for the reply.  I actually meant for R6 and R7 to be 10k... oops.  The "design" of this circuit (if you can call it that) is really just a combo of circuits I scoured from the internet.

The MIDI OUT portion is from :  http://www.neufeld.newton.ks.us/electronics/?p=250

The MIDI IN is from: http://midibox.org/forums/topic/7136-pc-900-vs-6n138/  I figured I'd try the PC900 version since I have one of those.

The relay circuit is from:  http://www.arduino.cc/playground/uploads/Learning/relays.pdf

I don't quite understand the suggestion of the 47k resistor between collector and emitter, could you maybe elaborate?


Updated drawing (sorry I couldn't get the image tag to work):

http://www.flickr.com/photos/33938419@N05/6182967223/
9  Using Arduino / Project Guidance / Guitar amp foot switch MIDI IN / MIDI OUT with relays on: September 25, 2011, 11:32:55 am
I want to convert a 3 button guitar amp foot-switch into a MIDI IN / OUT controller with 3 relays to also control the amp's channels and effects. 

My effects device is a Line6 M13.  The M13 sends MIDI messages when a "scene" is chosen (I'll be choosing scenes manually on the M13... no MIDI control for this).  The foot switch will receive these messages to determine which scene is currently active.  When a footswitch button is pressed, the footswitch will send a MIDI message OUT to the M13 to turn on/off any number of effects that make up a given scene.  (The three buttons will send differ messages depending on the active scene).  This will allow me to have 4 scene configurations with only pressing 1 of 3 buttons  smiley-twist

If anyone is up to it, please take a look at the attached diagram detailing the proposed circuit. Please let me know if I have the right parts chosen for the task and if I've made any general errors along the way.  I didn't add the power source or the footswitch buttons themselves to keep it from being too "busy".. Naturally I'll connect them between digi ins and ground with the internal pull-up resistors active.  Also, the relays aren't the actual one's I'd probably use (they are just ones that were in the Fritzing library).  I plan to use 5V relays like they have at Sparkfun.com

Thanks!!!


10  Using Arduino / Project Guidance / Re: Convert MIDI CC to variable resistance output for expression pedal input on: September 22, 2011, 06:12:36 pm
Thanks for the reply!  I'll have to stop by Radio Shack to get a TRS plug to connect to the exp. jack to read off the voltages.


I'm just concerned about tying the grounds of both the exp. pedal jack and the Arduino circuit.... is there NO risk there?  As I said, I REALLY can't afford to fry anything on the M13.


For the communication bit, would I just use the Arduino Serial commands to read in the MIDI data and then something like the SPI library to send the data that updates the digital potentiometer (assuming the pot supports this)? 

btw... has anyone seen a product on the market that does this????

If this idea is solid, I may through in some relays to switch amp channels if that's doable.... it seems it would be simpler than the MIDI to exp. converter bit... are "input control side" of relays electrically isolated from the switch side (at least for this purpose)?

11  Using Arduino / Project Guidance / Convert MIDI CC to variable resistance output for expression pedal input on: September 22, 2011, 03:25:13 pm
I have a Line6 M13 guitar effects processor that doesn't accept MIDI input to control effect parameters.  It has 2 expression pedal inputs (Tip-Ring-Sleeve I presume) for this purpose.  I want to control my M13 from a MIDI foot controller and MIDI expression pedals (i.e. Ground Control Pro or Roland FC-300).

Can I rig up something with an Arduino, with a MIDI input circuit, that ingests the MIDI data, processes the CC portion, and updates the value of a digital potentiometer that would be used as the input of the M13's expression pedal input?

The MIDI chain would be:  Ground Control Pro --> M13 MIDI IN,  M13 MIDI THRU --> awesome Arduino black box;  Arduino black box --> M13 expression pedal input.

My concerns are connecting the multiple DC systems (MIDI input, Arduino powered by wall-wart, expression pedal input) that may or may not have the same electrical reference, yada yada yada...

I don't know the electrical characteristics of the M13 Exp pedal jack... I'm assuming (hoping) it's a ground, 5V source, and a high impedance input to read the value from the pedal connected. 

What are your thoughts... I really don't want to fry anything on my M13... that would kind of ruin my day................ month, and year, really.

Thanks!
12  Using Arduino / General Electronics / Re: DC barrel socket with 3 contacts question on: April 23, 2011, 02:43:39 pm
Thanks for the explanations!!!
13  Using Arduino / General Electronics / DC barrel socket with 3 contacts question on: April 23, 2011, 12:32:36 pm
So, here's a simple one for you guys... can someone explain to me what the 3 contacts are for in a 3-contact DC barrel socket?  I know one is hot (+) and one is for ground (-)... just not sure how the other comes into play.

Thanks!
14  Forum 2005-2010 (read only) / Bugs & Suggestions / Re: min currrent to make pin go high??? on: March 17, 2009, 08:34:38 pm
I suppose I can, if I can find a dual-concentric pot that is the right physical size to mount on an electric guitar... I was getting pretty good results (from what I could tell) using the 500K pot I have just testing out the "technique" you guys mentioned.  The other pot on the dual-pot will be used in the actual guitar signal chain, so that is a consideration, as well.
15  Forum 2005-2010 (read only) / Bugs & Suggestions / Re: min currrent to make pin go high??? on: March 17, 2009, 03:54:41 pm
Worked like a charm.... I did notice (using the millis() function that the analogRead() function added ~50ms to the run time of my program (once through my loop() function).  I don't have a 100k pot on hand right now, just the 500k... and I don't have enough large resistors to play around with this, but, i was wondering if there is a way to calculate how long the analogRead() function takes depending on the current applied.
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