New module shift_in and shift_out for using shift registers

[Peter-van-Tol]

Discussed in #52

^{Originally posted by Peter-van-Tol October 15, 2023}
When using the 5A-75B, one can get at the point that 51 pins are not enough. The Arduino platform offers two libraries for shifting data using buffers:

• 74HCT595 for output;
• 74HC165 for input;

Using these chip, one can use for example a pendant with loads of functions, connecting the MPG directly to the pins and connecting the buttons to these shift registers.

Design spec:

• each module can handle up to 32 output (shift_out) or 32 inputs (shift_in);
• pins required are DATA, CLK and LATCH;
• input and output cannot be mixed on one channel;
• support for multiple channels, no overlap in pins.

Should this prove useful?

[Peter-van-Tol]

Tasks:

• shift_out:
  • firmware
  • driver
  • documentation
• shift_in:
  • firmware
  • driver
  • documentation