to display decimal dots on MAX7219 based 7-segment displays I like to use the NoiascaLedControl.h lib
found at: Arduino Noiasca LED Control with print method (MAX7219/MAX7221)
However incuding #include <NoiascaLedControl.h> the lib manager couldn’t find this library anyway.
Thanks for any hint
The library is not registered with the library registry (PlatformIO Registry). So you either have to download https://werner.rothschopf.net/2019/NoiascaLedControl.zip manually and put the library in the lib/ folder of the project, or add lib_deps = https://werner.rothschopf.net/2019/NoiascaLedControl.zip in the platformio.ini of the project. I would heavily recommand a local copy though, because you don’t know when that blog site eventually goes down.
Alternatively, use one of the 29 other registered arduino libraries that give you MAX7219 support – there’s no shortage of them.