AMiRo-OS

This file provides information about the purpose of this project, the file

structure and some helpful guides for development of code.

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CONTENTS:

  1  About the Project

  2  File Structure

  3  Developer Guides

    3.1  Adding a Device

    3.2  Implementing a Driver

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1 - ABOUT THE PROJECT

=====================

"periphAL", which is defined by this project. In order to configure which

drivers should be used in which version, the project expects an according file

"alldconf.h" to be found in the include paths.

2 - FILE STRUCTURE

==================

│     For each supported hardware device, there is exactly one directory in this

│     folder. Further subfolders may contain various versions of a driver (e.g.

│     'v1/', 'v2/', etc.). By convention the root directory of a driver is named

│     by the form

│     "<product_name>/"

│     The root header consequently follows the naming scheme

│     "alld_<product_name>.h"

│     and header files within the version folders shall be named like

│     "alld<product_name>_<driver_version>.h"

│     Any source files are placed in this directory. Naming conventions for

│     folders and files are the same as described before for the include

│     directory, as is the file structure. There is a dedicated folder for each

│     device and further subfolders for multiple driver versions. Source files

│     should only be put in these version folders.

3 - DEVELOPER GUIDES

====================

In order to keep all code within this project as homogeneous as possible, the

guides of these chapters should help developers to achieve functional and clean

results, which are portable and maintainable for future use. Whereas the textual

descriptions of the guides provide additional information about the underlying

concepts and mechanisms, a short summary is provided at the end of each chapter.

3.1  Adding a Device

--------------------

When adding new device to the project, the very first step is to create the

according folders in the include/ and source/ directories. For this guide, we

will add the fictional DEVICE1234. For this example the folders to be created

are "include/DEVICE1234/" and "source/DEVICE1234/".

The first file should be the root header: "include/DEVICE1234/alld_DEVICE1234.h"

Have a look at existing drivers and use one of those as template. This header

should introduce a new configuration to be set in the alldconf.h file and check

it using the preprocessor. Eventually, another header is included, pointing to

the selected driver version/implementation.

Such implementations are to be put in further subfolders, e.g.

"include/DEVICE1234/v1/" and "source/DEVICE1234/v1/". The header and C-source

files in those folders do not follow a strict scheme, although there are some

conventions to consider (i.e. naming conventions, cf. chapter 2).

Summing up, you have to

1) create device folders.

2) add a root header.

3) add further subfolders and implement the driver there.

3.2  Implementing a Driver

--------------------------

Implementation of a new driver usually is very straight-forward. You most

probably have a comprehensive datasheet of the device, or the manufacturer even

provides a reference driver implementation.

For the former case, you should first write a comprehensive header, containing

all information like constants, register maps, etc. and according abstract

access functions (e.g. for reading and writing registers, and convenient access

to common functionalities). Only the you implement those functions, using

periphAL to interface any hardware interfaces (e.g. I2C, SPI, etc.).

For the latter case, the reference implementation will specify some interface

functions to interact with the hardware (e.g. I2C, SPI etc.). Even though all

functionality should be covered by the reference driver, you still need to

implement those interface functions.

Since AMiRo-LLD does not rely on specific hardware or operating system, the only

valid way to interact with both is through periphAL. Under no circumstances you

must use any function of your operating system and directly or indirectly access

the hardware of your platform. For your driver, there is no knowledge about the

world beyond periphAL! If periphAL does not provide the function you need, you

can do the following: 1) Think again if you really need that funcionality or

whether it can be replicated by existing functions. 2) File a feature request

to extend periphAL. 3) Write a custom patch that modifies periphAL to meet your

requirements.

Summing up, you have to

1) Get and read the datasheet of the device (A) or

   acquire a copy of the reference implementation (B).

2) Case A: define constants, register map and access functions in a header file.

   Case B: identify the interface functions of the reference implementation.

3) Implement the missing functions using periphAL.