Using Teensy with Axoloti

[mongrol]

In my search for the nicest, most flexible way to add extra buttons and knobs I'm wondering where Teensy can fit in. I envisage connect extra controllers to the Teensy and somehow sending them over Midi to the Axo. Is it possible to input Midi to Axo without using USB? I'd rather keep everything internal to my box and leave the USB free for proper controllers.

[gloom_and_glare]

axoloti/axoloti/blob/master/firmware/serial_midi.c

?

[janvantomme]

How many buttons and knobs do you want to add? You can connect up to 16 with the available ports. If you really need more, you can use a 4051 chip. Sending MIDI to the Axoloti is best done via USB, or the oldskool DIN MIDI ports.

[GPIO I/O] Example 4051 de/multiplexer reads 8 analog sources

Hi everyone, here is a short example for a 4051 de/multiplexer. The 4051 can be used for extra 8 analog outputs or inputs. The Y0-7 pins are choosen by HIGH/LOW state of the S0-2 pins. It's not the fastest way to expand the analog input or output, but the IC are very cheap and I own a lot of them [sweat_smile] It's good thing to decouple the analog inputs and VCC with a 100n capacitor. A MCP3008 or MCP3208 SPI is much faster and has an input protection build in. An examples for this IC will b…

[mongrol]

My design has me a tad over what's available. I'd like to add a mod matrix like the microbrute so I can route env and lfo's to different destinations. Either via buttons or banana plugs. So 8 extra would do it. Probably the 4051 route would be easier than coding on another platform.

[mongrol]

This looks good. Talks over i2c so I assume would need an Axo object written for it. Should be too hard and would look great. Like a mini Matrixbrute

https://learn.adafruit.com/adafruit-trellis-diy-open-source-led-keypad/overview

[mongrol]

Back on the serial midi topic again. There is a serial object that sets the baudrate and enables the port on PA2&3. All good. But if I'm talking midi how do I use the midi/in objects with this? The only devices available are the DIN/Internal/USB. I don't see any objects that actually operate over serial other than the one that enables the port.

Edit: Just looking at the board I see headers available behind the DIN sockets. Win! I just need to knock up a little teensy midi breadboard with DIN in/out on it and join them together.

[gloom_and_glare]

I rarely ever use MIDI, so I haven't tried this myself. But yeah, the midi serial stuff seems to default to the UART available via the DIN connectors resp. on JP2/3, that is PG9, PG14 (assuming BOARD_AXOLOTI_V05 is the latest revision)

To use PA2/PA3, you'd have to edit serial_midi_init(void), I suppose

[igor]

Hi to all! Bumping old thread

Would it be possible to access remote control stream using UART (instead of USB)? Or to change the code so that everything that goes to/from USB also goes to UART? I'd like to make hardware remote (same as the software one) but don't know how to access the control data stream.

[mongrol]

What do you mean control data stream?

I'm using a Teensy to control the Axoloti via serial Midi. There's a header behind the MidiIN socket you can attach the Teensy UART to then using the Arduino MIDI library you throw Midi-CC's or Notes at it. Works very well.

[igor]

I'm aware of that but I need MIDI for other things (foot controller). I was thinking about the data stream used for remote control in Axoloti application.

[thetechnobear]

Or to change the code so that everything that goes to/from USB also goes to UART

more likely could be added as an extra midi target.
(also if your interested in parameters this can already be done, see my Push example in the Community library)

which pins do you want to go via? as @gloom_and_glare pointed out, perhaps have a look at the existing serial midi implementation.

another possibility if your not up to extending the firmware, is to use MIDI DIN, they are completely separate from USB midi.

[johannes]

I was thinking about the data stream used for remote control in Axoloti application.

For that approach you'd need to hack into the firmware. The actual screen bitmap rendering and interaction is managed in the axoloti firmware so far, you could hook into that. The data stream is available on SPI3 (X3 header connector), code axoloti_control.c:do_axoloti_control
Documenting all the bits 'd take time away from actual development, and is likely subject to change...

[igor]

The actual screen bitmap rendering and interaction is managed in the axoloti firmware so far, you could hook into that. The data stream is available on SPI3 (X3 header connector), code axoloti_control.c:do_axoloti_control

That's exactly what I need. Documentation shouldn't be problem since I know a bit about ChibiOS and STM32 but I wasn't sure just where to start (just got my Axoloti yesterday). Thanks!