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[on:]

I am totally new to this world, but am a software programmer with a strong analog electronics background.

I am attempting to build a control surface for controlling audio recording software.

Here's a nice illustration the motorized fader concept:

http://www.youtube.com/watch?v=toj8JRJ-4rI&feature=youtu.be

Each fader requires 5 pins:

1 analog pin to sense the wiper

2 I/O pins for touch sense

2 PWM pins to drive the motor via an H bridge.

There would also be 2 dual concentric ELMA E37 rotary encoders with push top switches:
http://www.leobodnar.com/shop/index.php?main_page=product_info&products_id=196

That's 10 more pins:

2 per encoder x 4 = 8
1 per switch x 2 = 2

As well I'm thinking of using 2 x 4D uOLED-128-G2 displays (one for channel status and one for metering)
http://www.4dsystems.com.au/prod.php?id=84

As far as driving the metering display, I'm thinking of loading background images from the 2Gb SD  card included on the display board and just doing "delta" meter drawing to save bandwidth.
I believe these guys need 3 pins each - so total 6 pins.

We also need 2 more switches -- 2 more pins

So 23 pins per channel.

I was hoping to drive 4 of these "channels" with 1 Arduino Due but that would require 92 pins.

I also would like to use Ethernet for communication.

With the Due running at 84 MHz is it feasible to multiplex the simple on/off switches and still have a very responsive system, thereby getting within the avaiable pin count?

[Reply #1 on:]

I am attempting to build a control surface for controlling audio recording software.

What is a "control surface"?

With the Due running at 84 MHz is it feasible to multiplex the simple on/off switches and still have a very responsive system, thereby getting within the avaiable pin count?

For some purposes, yes. For others, no.

Encoders really need interrupts to avoid missing any pulses. 4 encoders will need 8 interrupt pins. No Arduino has 8 external interrupt pins. And, no they can't be multiplexed.

[Reply #2 on:]

Thanks for the quick reply !

What is a "control surface"?

Here's an example, it's like a audio mixer, but no actual audio passes through it:



It simply controls software in the computer which actually handles the audio.

I coded the software in this video, now I'd like to take this further with more control over hardware.

Encoders really need interrupts to avoid missing any pulses. 4 encoders will need 8 interrupt pins. No Arduino has 8 external interrupt pins. And, no they can't be multiplexed.

Hmmm....

This is from the Arduino Due page, am I missing something? (As I said I'm a total noobie)

The Arduino Due board has powerful interrupt capabilities that allows you to attach an interrupt function on all available pins. You can directly specify the pin number in attachInterrupt().

[Reply #3 on:]

am I missing something?

Well, my Due is stuck in customs. So, I can't confirm or deny this.