The plumCore DAQ framework

A modular framework for data logging and remote data acquisition.

The name represents a seed found in a plum fruit - the "core" of the plum. Although not used in this manner it sounds sufficiently good to be used as a name for a totally unrelated project.

Current develop branch

Introduction

plumCore is a C framework using the microkernel/services pattern. FreeRTOS scheduler is used as the microkernel providing task scheduling and a basic IPC. All the rest is implemented as modular services. A plumCore service provides interfaces used by other services. Interface dependencies are either discovered in runtime (service locator pattern) or injected (dependency injection). Even the service locator is implemented as a service. Most of the code looks like and behaves in an OOP manner. As an user interface, a tree-structured CLI (command line interface) is available to configure the device.

plumCore use cases are various remotely operated measurement/DAQ systems with optional on-site data processing (edge computing). IoT and consumer hardware are not plumCore's target applications.

Concepts and design goals

• Thin wrappers for external libraries - whenever an external library providing a common service is used, it is wrapped in a thin wrapper exposing a defined Interface.
• The less supported platforms and compilers, the better - plumCore is not aiming to be the most universal and the most widely used framework among all industries. To achieve our goals, we need fully featured MCUs with capable peripherals. Hence, the list of supported platforms is pretty short.
• Strict pattern usage and coding style
• Microkernel/services architecture - we are moving towards the microkernel architecture where the kernel has only some essential parts and all other components are implemented as services. Currently, this is not the case. We are using FreeRTOS and some of its functionality which will go away in the future.
• Dynamic ELF loading of the framework components (services)
• Strict code and functionality organisation - services, applications, jobs, applets
• Strict rules for passing dependencies - there are only two patterns for passing dependencies among services - dependency injection and service locator
• Message queue data passing - the framework contains a message broker service for passing data between services. The data is always passed in a common datatype resembling NumPy's ndarray.
• Selecting the best from all worlds - plumCore uses a bit of a naive approach, because it is easy. It uses a bit of Misra's approach, because it is supposedly safe. It requires all functions to return a result of their execution and you are recommended to check it every time. We are not banning dynamic memory allocation, but we have strict rules for it. We are programming defensively, but not too much to be contraproductive.

Current status

The project is currently undergoing many changes and should be considered alpha-quality. It contains many known defects and legacy code dating back to 2015. Even in these circumstances it is being actively run on some commercial products in field.

Resources

to-do:

• downloads
• host tools, flashing the firmware
• documentation
• list of hardware

Very quick-start guide

Get the source code:

git clone --branch develop https://github.com/iqyx/plumcore.git

Create a python virtual environment and install the required packages:

python -m venv venv
source venv/bin/activate
pip install -r requirements.txt

Create a private Ed25519 key for signing the resulting ELF. Get the public key too:

python -c "import hashlib; import base64; print(base64.b64encode(hashlib.sha256(b'default-key').digest()).decode('utf-8'))" > elfsign.key
scripts/elfsign.py --sk elfsign.key -p elfsign.pub

Build for the selected configuration, strip and sign the resulting ELF:

defconfig config/your_hardware_defconfig
scons firmware-sign

Community

to-do

Code management, contributing

Source code of plumCore is kept in a git repository on Github. GitFlow workflow is used for development together with SemVer 2.0 for versioning. Kconfig is used for compile-time configuration. Sources are built with scons.

Report bugs using issues, contributions are welcome using pull requests.

Licensing

All code is released under the GNU GPL v3 (or later) license, see reasoning (to-do). There are parts of the project still licensed under the 2-clause BSD license, it will change in the future.