MIDI foot controller

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sixeight

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This summer I want to build a MIDI foot controller to control a Boss GP-10, a Roland GR-55 and possibly a VG-99 as well. More info on these guitar processors can be found on vguitarforums.com where my nickname sixeight as well.

Features:
- Teensy LC
- MCP23017 for extra ports
- 12 momentary footswitches
- 12 LEDs (RGB?)
- 1202 LCD display with serial interface
- USB midi and serial midi at the same time - possible two midi in and 2 midi out ports
- The pedal should have several modes for controlling the different pedals and a control mode, where i am able to send and receive sysex and other controller MIDI commands.

So far I have the Teensy LC and the MCP23017 talking to eachother, using the adafruit_MCP23017 library and changing wire.h to i2c_t3.h. I am still waiting for my LED display, which should arrive anytime soon from China.

A few questions:
1) Does the default midi library support use of several serial ports at the same time?
2) what is the best way to control 12 RGB LEDs with common cathode?
3) If I compile an empty sketch for the Teensy LC, it already seems to use 16% of the available 64k Flash and 31% of RAM. What is this space used for?
 
1) Does the default midi library support use of several serial ports at the same time?

I believe it's designed for a single port.

Some versions, perhaps newer copies, are designed to allow multiple instances of the library, each using its own port.

2) what is the best way to control 12 RGB LEDs with common cathode?

You may need to use a 5V chip to drive the blue and green LEDs. Look for a 74 series logic chip with the letter "T", like 74HCT or 74ACHT or similar. Perhaps a shift register.

3) If I compile an empty sketch for the Teensy LC, it already seems to use 16% of the available 64k Flash and 31% of RAM. What is this space used for?

The USB stack takes a good portion. There's also a known limitation where all 3 serial ports have their code built in, even if you're not using them.
 
I found another solution for my multicoloured LEDs:

https://www.adafruit.com/products/1938

The 5 mm version of the neopixel LED. Now I just need one pin on the Teensy and it saves a lot of soldering time as well. I was able to buy them in the Netherlands at a very reasonable price.
 
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