Pi => Nano => MAX7219

[DaveX]

@morgon123

Unfortunately it seems there is no way to control the 5v pin via software so from what I have gathered you would need to use a mosfet and this is something I know nothing about...

A high-side power switch module like this could work for controlling a 5V pin:

Pololu - Mini Pushbutton Power Switch with Reverse Voltage Protection, SV

Look into this:

Serial Input Basics - updated

Updated Version Please note that this is a revised version of the advice in this earlier Thread which has become very long. As far as possible I have kept the code examples identical or simplifed them slightly. It should not be necessary to refer to the older Thread, but feel free to do so. Contents The following sections are in this Tutorial Introduction Serial data is slow by Arduino standards Example 1 - Receiving single characters Why code is organized into functions Exampl…