MicroPython code for RaspiTV's InsPiRing
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README.md

MicroPython code for Raspi.IO Inspring

This is an experimental micropython library for Alex Eames' (@RaspiTV) InsPiRing strips.

The API will almost certainly change, and may change in ways that break existing code!

InsPiRing with microbit

Software

I have only done limited testing so far.

This version now uses a list of bytearrays in order to reduce memory requirements, and intensity values should be in the range 0-31.

This is not a problem if you are just driving a short strip of LEDs, but it would be if you were driving larger LED arrays or doing lots of other things as well.

My next priority is to test the code with larger LED arrays.

Hardware

My current hardware setup works but is not recommended.

I am currently living dangerously because

  1. I am using the BBC micro:bit to provide power to the LEDs.
  2. I am not using a level shifter for the SPI lines.

I have connected the 0v, Vcc, CI and DI pins of the LED array to 0v, 3V and Pins 13 and 15 of the microbit but this simple approach is not ideal for the reasons given above.

Even with 8 LEDs in the array, the micro:bit gets dangerously hot if several LEDs are on at once.

One of the larger LED arrays with all LEDs on full brightness would undoubtedly exceed the power available from the micro:bit.

Once I have a larger LED array to play with I'll rewire using an external power supply, and I may use a level shifter for the SPI lines.

Usage

The file inspiring.py contains a simple example.

Your code should:

  1. Construct an instance of Apa, specifying the number of LEDs.
  2. Initialise the SPI bus.
  3. Set one or more LEDs, specifying the LED number, counting from 0, the intensity (brightness) ranging from 0 (off) to 31 (very bright) and the r, b, g values, which are integers in the range 0-255.
  4. Tell the Apa instance to show the updated LEDs.

Then repeat steps 3 and 4 as necessary.