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.

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.

• 1. Introduction
• 2. Concepts and design goals
  • 2.1. Thin wrappers for external libraries
  • 2.2. The less supported platforms and compilers, the better
  • 2.3. Strict pattern usage
  • 2.4. Strict coding style
  • 2.5. Microkernel usage
  • 2.6. Code and functionality organisation
  • 2.7. Strict rules for passing dependencies
  • 2.8. Message queue data passing
  • 2.9. Selecting the best from all worlds
  • 2.10. VCS and build system
• 3. Getting started
• 4. plumCore microkernel documentation
• 5. Services
  • 5.1. Low level device drivers
    • 5.1.1. STM32 12 bit SAR ADC driver
    • 5.1.2. STM32 DAC driver
    • 5.1.3. STM32G4 FDCAN peripheral driver
    • 5.1.4. STM32 I2C peripheral driver
    • 5.1.5. STM32L4 low-power MCU family power manager
      • 5.1.5.1. Dependencies
    • 5.1.6. STM32 QSPI flash memory driver
    • 5.1.7. STM32 RTC peripheral clock driver
      • 5.1.7.1. To-Do
    • 5.1.8. STM32 SPI peripheral driver
    • 5.1.9. System clock implemented using STM32 timer
    • 5.1.10. Capacitive sensing implemented using STM32 timer
    • 5.1.11. STM32 UART driver
    • 5.1.12. STM32 watchdog peripheral driver
  • 5.2. High level (second level) device drivers
    • 5.2.1. adc-sensor: Measuring a single analog sensor with an ADC input
    • 5.2.2. bq35100: Primary cell gauging using a TI’s BQ35100 gauge
    • 5.2.3. gps-ublox: A generic driver for u-blox based GNSS receivers
    • 5.2.4. gsm-quectel: Service for accessing Quectel cellular modems
    • 5.2.5. ICM-62688-P 3 axis accelerometer and 3 axis gyroscope driver
    • 5.2.6. ADXL355 3 axis accelerometer
    • 5.2.7. Si7002/7021 temperature and humidity sensor driver
  • 5.3. DAQ and data processing services
    • 5.3.1. data-process: A flow graph data processing framework
    • 5.3.2. MQ data batching service
    • 5.3.3. MQ -> LoRaWAN bridge
    • 5.3.4. MQ periodogram computation using the Welch method
    • 5.3.5. MQ WaveformSource source
    • 5.3.6. MQ data statistics service
    • 5.3.7. MQ WaveformSource source
  • 5.4. Volume and filesystem access
    • 5.4.1. fs-spiffs: SPIFFS filesystem library wrapper service
    • 5.4.2. MIB stored in a flash device in a CBOR format
    • 5.4.3. FIFO in a flash device
    • 5.4.4. NVM (non-volatile memory) key-value store in a flash partition
      • 5.4.4.1. Example
    • 5.4.5. Flash memory test suite
    • 5.4.6. Flash volumes service (static configuration)
    • 5.4.7. LoRa filesystem services
      • 5.4.7.1. (anti)Features
      • 5.4.7.2. Main concepts
  • 5.5. Communication protocols
    • 5.5.1. mqtt-tcpip: Connect to a MQTT broker using TCP/IP
    • 5.5.2. NBUS CAN-FD sensor bus driver
  • 5.6. Communication server/clients
    • 5.6.1. mqtt-file-download: Service for downloading files from a remote server over MQTT
    • 5.6.2. mqtt-file-server: Server for providing file access services over MQTT
    • 5.6.3. mqtt-sensor-upload: Periodically upload sensor data over MQTT
  • 5.7. User interface services
    • 5.7.1. Login manager service for command line interfaces
    • 5.7.2. Command line interface (hierarchical type)
  • 5.8. Generic system services
    • 5.8.1. A service locator service
• 6. Interfaces
  • 6.1. Power source/sink device interface
• 7. Applications
• 8. Applets
  • 8.1. What are applets
  • 8.2. Tutorial: create your own applet
• 9. nwDAQ CAN communication protocol (nbus)
  • 9.1. Network topology
  • 9.2. Logical addressing
  • 9.3. To-do section
  • 9.4. Minimum channel descriptor contents
• 10. Ports
  • 10.1. nwdaq-br28-fdc 8-channel, 24 bit full bridge strain gauge digitiser
  • 10.2. nwdaq-rtd18-fdc 8-channel, 24 bit RTD sensor digitiser
  • 10.3. nwdaq-if-lpcan CAN/CAN-FD interface plug-in unit
• 11. Conceptual
  • 11.1. On position independent firmware images
• 12. Code structure, contributing
  • 12.1. Git version control system
  • 12.2. Gitflow workflow
  • 12.3. Contributing
  • 12.4. Semantic versioning
  • 12.5. Conventional Commits
  • 12.6. Continuous Integration
  • 12.7. Release artifacts
    • 12.7.1. Firmware builds
    • 12.7.2. Documentation builds
• 13. Coding style guide
  • 13.1. Variable, type and function names
  • 13.2. Types
  • 13.3. Macros
  • 13.4. Return values
  • 13.5. Spaces
  • 13.6. Indentation
  • 13.7. Line length
  • 13.8. Code blocks, curly braces
  • 13.9. if-then-else
  • 13.10. switch
  • 13.11. Comments
  • 13.12. Copyright headers
  • 13.13. Includes
• 14. Enhancement proposals
  • 14.1. EP-73c: Login manager implementation
    • 14.1.1. Motivation
    • 14.1.2. Feature specification
      • 14.1.2.1. Accessing the diagnostic console port
      • 14.1.2.2. Wakelock
      • 14.1.2.3. Channels and multiplexing
      • 14.1.2.4. Multiplexing using escape sequences
      • 14.1.2.5. Stream protocols
      • 14.1.2.6. Datagram protocols
      • 14.1.2.7. Logout after inactivity
  • 14.2. EP-2a9: ELF object store
    • 14.2.1. Requirements
      • 14.2.1.1. XIP and mmap
      • 14.2.1.2. Extents
      • 14.2.1.3. Metadata
      • 14.2.1.4. Preallocation
      • 14.2.1.5. Defragmentation
      • 14.2.1.6. Supported backing storage
      • 14.2.1.7. Simple block allocation
      • 14.2.1.8. Basic data structure
    • 14.2.2. Resource considerations
  • 14.3. EP-c55: Configuration tree
    • 14.3.1. Motivation
    • 14.3.2. The proposed changes
    • 14.3.3. Value flags
    • 14.3.4. Value types