Every company has its own coding style. My coding style is deducted from the one, i’ve been using in automotive company because it is best readable style from my point of view. I will try to explain it why it makes sense.
Variables
Variables shall use lower camel-case style. The name CANNOT be less than three letters. Why? Because every variable has to have meaningfull name. I am really annoyed when reading x,y,z and similar naming even for indexes in for loops. It does not make a sense and reading is terrible.
The existence of external variables shall be prohibitted and creator shall be publicly lynched. The control of reading and writing values into this variables are almost untraceable. Only way, is to search them through project and check, where are readed and where are written. Always use setters and getters!
Data types
Type names shall same as variable use lower camel-case style but, it has to end with _t. Same like uint8_t, uint16_t, uint32_t and so on. So you will always know if you are using type, or variable.
In project i dont use generic types as uintX_t. Instead of that, i use type definition and create own name for the generic type. This helps you prevent mixing different types. If you will calcualte temperatures and somehow you will use humidity variable, you will get an error about using different variable types. And that’s the point you want. This will reduce development process time and problem finding.
Function names
Function names shall use upper camel-case style. You have immediate information if it is variable, function or type. Also is really important to use module prefix as function prefix. At the end you will get list of all functions and you will always know, where is the function located in hierarchy.
Preprocessor directives
The preprocessor directives shall use upper case. This style will immediatelly inform another developper, that preprocessor directive is not built-in.
File names
File names shall sue upper camel-case style. The begin of name shall be name of module followed by underscore and file functionality description.
The files organizations is described in different topic.