Below, you'll find comprehensive technical specifications outlining our Slim MIDI interfaces tailored specifically for Raspberry Pi. Accompanying these details is a thorough description of the connectivity options at your disposal, empowering you to make informed decisions about what can be done with the Slim MIDI interfaces.
MIDI IN and MIDI OUT mini jack connectors
These connectors follow the standard mini jack MIDI Type-A specifications, and are designed to operate at a buffered 5 volts, for maximum compatibility across various devices and setups.
They are connected to the Raspberry RX/TX UART0 pins (8 and 10) so that you can use them with the Linux standard serial port libraries. You can also run ttymidi-sysex to add Alsa compatibility. Peep at the links below for more!
16 I/O headers
If you're equipped with a SLIM MIDI Hat version 1.2 or higher, you'll find its 16 pins seamlessly integrated with an MCP23017 chip. This tiny yet mighty chip significantly amplifies the Hat's capabilities by adding 16 versatile Input/Output (I/O) pins to its repertoire. These pins can be dynamically configured as either inputs or outputs, granting users unparalleled flexibility in their MIDI Hat projects.
It's worth noting that the maximum voltage each of these pins can handle is 5 volts
As you can see on the photo above, the outer row is connected to Port A and the inner row to Port B. The Chip addess is 0x21.
If you want to use the 'interrupt mode' of the Chip:
- INTA is connected to Pin 36, GPIO16 on the Raspberry
- INTB is connected to Pin 37, GPIO26 on the Raspberry
Programming info:
- Connecting a rotary encoder to the MCP23017 using Circuit Python
- In Circuit Python + Blinka for the Raspberry: https://learn.adafruit.com/using-mcp23008-mcp23017-with-circuitpython/overview
- In Python: https://github.com/sensorberg/MCP23017-python
- Some Zynthian boards use the same chip
Please take note: The v1.1 board does not come with the MCP23017 chip pre-soldered. However, for those with advanced soldering skills and access to the appropriate equipment, there is the option to manually add the chip to the board.
SPI pins
If you possess a MIDI Hat version 1.2 or higher, you'll find that the 4 pins are linked to the Raspberry Pi's SPI port.
Pins description:
- GND
- +3.3v
- SCK
- SDA
You can solder an OLED screen on these terminals or any other SPI device:
- Python + OLED screen: https://pypi.org/project/Adafruit-SSD1306/
Configuration and Python programming
Explore our informative article for detailed instructions on configuring the MIDI serial port and delve into a variety of Python MIDI programming examples.
Should you have any further inquiries or require clarification, don't hesitate to drop us a comment or message. We're here to assist!
