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Reference Guide

This page aims to describe the GrowNode API and how to use it to develop your own firmware.

Disclaimer: This is NOT intended for ready-made solution users. Don't tell me I've not warned you! :)

GrowNode is based on the ESP32 microprocessor, and is developed on top of the ESP-IDF Development Framework. This allows one to directly access to the ESP32 functionalities and the real-time operating system (RTOS).

In order to mantain a coherent code style and ease the access of all ESP-IDF functionalities, GrowNode is written in pure C, although a C++ version could be done in next future.

Basic Concepts

The highest level structure on a GrowNode system is the board itself. Every solution you want to build is basically a combination of:

  • Devices attached to the IO pins (typically handled by specific HAL - Hardware Abstraction Layers - like ESP-IDF core libraries or third party devices). Examples: I2C driver, a GPIO pin

  • Several logics to access to those devices, which are called Leaves in the GrowNode framework - several are prebuilt and more can be user defined. Examples: a temperature sensor, a relay, a LED, a motor

  • Several Parameters exposed by/to the Leaf, able to retrieve/command specific functionalities. Examples: the temperature retrieved, a motor switch, a light power

  • One centralized controller that exposes to the Leaves the services needed to work, called Node. This is common on all the GrowNode implementations

  • one entry point of the application, where the Node and Leaves are declared and configured, called Board. Examples: a Water Tower Board, a simple Temperature and Humidity pot controller

Architecture

In ESP-IDF vocabulary, the Board and its corresponding Node works in the main application RTOS task, and each Leaf works in a separate task. This allows the parallel execution of task logic and, moreover, avoids that a leaf in waiting state (eg. waiting for a sensor measure) affects the running of the whole Node. All messaging across leaves is implemented through RTOS events and message queues.

Putting all together, here's an overview of GrowNode platform:

Code reference

Code Documentation is described in API section. The entry point of all GrowNode functionalities resides in the grownode.h header file. Users just have to reference it in their code.