advice on how to make my A2 project?

[aoife_mac]

hi everybody,

so basically for my a2 project, i'm designing a small, portable guitar practice tool
which basically consists of 4 frets, with strings that you can strum and pluck.
i want it to be able to mimic the way a real guitar works, ie. the note that is played when the string is plucked is relative to what's happening on the neck.

i want the project to be completely systems based, because it eliminates the need for tuning.

heres a simple diagram:

http://i40.tinypic.com/10rsun4.png

do any of you have any suggestions or ideas as to how i could go about designing the systems for this idea? or recommend me specific picaxe components that might be suitabe? i realise i haven't articulated it very well, it's hard to explain in words, so please ask questions if i've lost you!

 

[geoff07]

Think about the 'touch' inputs and how they might detect string work or fret work. You might need a bunch of Picaxes but they are inexpensive. A 40x2 has 27 touch inputs. I don't know if they can be calibrated for pressure/contact strength but if they can that would help, to provide some 'feel'.

 

[nick12ab]

To clarify, are you trying to make a device that does all of this:

• detects which buttons on the neck you're pressing
• detects which strings are being plucked
• detects how hard the strings are being plucked
• outputs sound depending on all of the above

Have you tried using the sound capabilities of the PICAXE? You'll find that a PICAXE can only do monophonic sound. However, a way that it could be done is to have a separate PICAXE for each string and they all output sound. The top-of-the-range 28X2 and 40X2 shouldn't be needed - any given PICAXE just needs to produce a short bit of sound, check the status of the inputs, then immediately produce another bit of sound or just produce silence.

Process per PICAXE:

• detects what strings are being plucked and how hard
• reads the buttons (touch sensors on M2/X2s a possibility)
• does calculations
• outputs approx 20-50ms of sound
• does all of this again

 

[geoff07]

If you have some sort of midi output device it might be best to send midi data to that and then you could have 'real' polyphonic output that actually sounded like a guitar. Picaxe-synthesized guitar will sound like exactly that I think.