get multiplexed inputs into pure data

Fedde

Hi Guys,

For my project I need some more analog inputs than the standard 10 that are available.

I hooked up a 4051 to my Bela. The A, B and C control pins from the MUX go to P8 pins 45, 46 and 43, respectively like Andrew explained.

[adc~ 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17] only gives me values from the first 10 inputs.

I realise that I actually don't know how to get the multiplexed inputs into pure data. Is there an example available that discribes how to do this?

giuliomoro

If you enable the multiplexer capelet in the command line options, then you can use the example 08-PureData/multiplexerCapelet, to access them.
When the multiplexer capelet is enabled and there is an array in your patch called bela_multiplexer, this array will be updated in the background with the multiplexed values as they come in.

Fedde

I had to update the Bela-master.zip. The mux command line options are now accessible via the IDE. It's working just fine now. Thank you for your help.

giuliomoro

Make sure you get the latest version of the code https://github.com/BelaPlatform/Bela/wiki/Updating%20Bela.
In that, the IDE allows you to set the number of multiplexer channels through the GUI.

If you are using the terminal, you can get help on the command line options, by running

./run_project.sh projectName -c '--help'

from the scripts/ folder.
This runs your project with command line option --help, which dumps the help for the project (unless you are using a custom main file, this is going to be the default set of options).
More info on passing command line options can be found here.

zimtzeke

hallo giulio,

what would you suggest as fastest readout option for the multiplexer capelet in combination with puredata?

i'm trying to read 64 analog signals and then send them via netsend to my computer.
everything is working but the 'sample-rate' of the 64 mux channels is too low/slow.

with the [metro] readout i cannot go lower than 200ms (~ 5Hz per channel) for 64 channels. when I try to get faster readouts of the [bela_multiplexer] table in the example patch, pd goes crazy.
Underrun detected: 1 blocks dropped... 2 blocks dropped... bela stopped...

on the website i read that it should be possible to get 2.75kHz samplerate per channel for 64 channels. how do i achieve this directly from pd? is it possible to catch the [table] values directly from the system without using [table] and [metro]. something like [r tablevalues]?

or is a superfast readout and mux-value-processing only possible with C++?

thanks!

giuliomoro

it should be doable from Pd, although there may be a number of things to take care of in order for that to be smooth.
First thing: is your code up-to-date? There was a bug that was fixed a couple of months ago that could trigger this behaviour. Can you run grep PD_THREADED_IO /root/Bela/core/default_libpd_render.cpp in the console at the bottom of the IDE, and see what it returns? If it does not return the line#define PD_THREADED_IO, then it means you should update the code on your board.

Other stuff:

how are you putting together the [netsend] message? Assembling a long string can be CPU intensive, if that is the case, either consider splitting the message in smaller message, one per each [bang~], or increase the block size.
if you want to do something like [r tablevalues], you'd have to change the C++ code that wraps the Pd patch. Here's an introduction to how to do it https://github.com/BelaPlatform/Bela/wiki/Puredata-and-C--.