Pocket Sampler - Help needed

Hi all,

I'm pretty new to Arduino but I'm determined to complete the following project in one way or another. :astonished:

I want to build a pocket sampler with limited sequencer abilities on a Duemillanove.

  • I want to use at least 8 tactile buttons for playing back sounds. I will probably need 3 more function buttons such as play, stop, rec, maybe more.
  • I have a Wave Shield from Adafruit that can play back 16 bit 22khz wave files from an SDcard.
  • I chose a I2CLCDextraIO + green LCD as a screen for navigation, options, loading sound kit, etc. It uses up 2 pins only.
  • I want to build my own enclosure but I have no idea how to mount the tactile buttons because they have no screws or holes to mount them.
  • I'm also planning on attaching a LoL shield for step sequencer feedback

My questions are as follows:

  • Is this even possible?
  • How should I approach multiplexing inputs for the buttons? I need to be able to handle multiple button pushes at the same time.
  • How can I mount these tactile buttons? (LED Tactile Button - Orange - COM-10441 - SparkFun Electronics) I've got the breakout boards for them but these neither have any screws for standoffs as far as I can see.

Thank you for any help that you guys can give me :slight_smile:

Is this even possible?

While not saying no, it is not the easiest of projects, nor will the results be much good when you finish it.
You need some external SRAM to hold the samples before you transfer it to the SD card.

I want to build my own enclosure but I have no idea how to mount the tactile buttons because they have no screws or holes to mount them.

The least of your problems but these are PCB mounted switches so you have a PCB or strip board behind the panel and have a plunger arrangement to push them through a hole in the panel.

How should I approach multiplexing inputs for the buttons?

Use a port expander chip. This project uses one:-
http://www.thebox.myzen.co.uk/Hardware/Pendulum.html

Hi Mike,

You need some external SRAM to hold the samples before you transfer it to the SD card.

Is this necessary? I've made a test with the wave shield and I was able to play back sounds loaded on the card pretty fast when I pushed a button. For me the issue here is grouping sound files or indexing them in some way so I can create kits of sounds to play back.

Thanks for the valuable information. This is exactly what I was looking for! 8)

What Mike means, if you want to record audio (It's an Sampler, right ?!) You need to buffer the audio, as you cannot write directly to the SD card.

Writing to SD cards is done in blocks of data, the Arduino must sample data for a given amount of time, buffer this in some RAM, and when it's full it opens a block on the SD card and dumps the data, and goes on and on, but that is the basic principle.

// Per.

I don't want to record audio. I just want to record the steps on the sequencer to play back the sounds at the proper place.

Ok but that is what I would call a sample player rather than a sampler.
So a wave shield should do you then.

Hi

Sorry for the confusion.

I actually have these for each button LED Tactile Button Breakout - BOB-10467 - SparkFun Electronics but I don't see any mount points on them. Any ideas how to mount them?

thanks!

You can glue them to a panel with a hole for the tip of the switch. Or you can arrange for them to be mechanically pushed by some key top, much like I did in this project:-
http://www.thebox.myzen.co.uk/Hardware/Hexome.html
Although that might be going over the top.