How to write "CMakeLists.txt" for a big project with multiple subdirectories?

Question

I am working on a simulation project: Taking an embedded C codebase from a target platform and trying to simulate it on a Host computer for debugging or single stepping into the code.

OS: Ubuntu Linux 14.04, IDE: CodeLite, Makefile Generator: Cmake. I am confused about how to write CMakeLists.txt for the project. Following is the structure of codebase (it's all written in C):

|ARQSim\  
|-->ARQSim.h  
|-->ARQSim.c  
|-->BaseStationCode\  
|   |->downlink.c  
|   |->neoncopy.c  
|   |->armCore\  
|   |  |->common\  
|   |  |  |->Bsconfig.h  
|   |  |  |->config.h  
|   |  |->MacSource\  
|   |  |  |->lib\  
|   |  |  |  |->arqCommon.h  
|   |  |  |  |->OverTheAir.h  
|   |  |  |->source\  
|   |  |  |  |->beacon.c  
|   |  |  |  |->proxyDhcp.c  
|   |  |  |  |->ARQ\  
|   |  |  |  |  |->arqCommon.c  
|   |  |  |  |  |->arqInterface.c  
|   |  |  |  |  |->fragmentation\  
|   |  |  |  |  |  |->fragBookkeeping.c  
|   |  |  |  |  |  |->fragProcessAck.c  
|   |  |  |  |  |->reassembly\  
|   |  |  |  |  |  |->reasmBookkeeping.c  
|   |  |  |  |  |  |->reasmProcessAck.c

I am totally new to Cmake. I have read up a lot of resources on CMake and threads here on StackOverflow. But I get confused every time. Few questions I have:

1. Do I need only one CMakeLists.txt at root directory or every directory needs a different CMakeLists.txt file?
2. How to add the source files recursively in CMakeLists.txt?
3. What are the basic commands I need to put in CMakeLists.txt for MakeFile generation?

An example based on the structure of code mentioned above would be appreciated.

Answer 1

I was also looking for a more general way of adding CMakeLists.txt files to my projects. I decided to write a CMake generator (partly because I wanted to understand how CMake works):

https://github.com/Aenteas/cmake-generator

It has a couple of additional features such as creating python wrappers (SWIG).

Writing a generator that suits everyone is impossible but I hope it will give you an idea in case you want to make your customized version.