1. Official FreeRTOS Documentation: The official FreeRTOS website provides an extensive documentation set, including a user manual, which can be downloaded as a PDF.
2. FreeRTOS Tutorial by Antony D. (2018): This tutorial provides a detailed introduction to FreeRTOS, covering topics such as task management, synchronization, and communication. The tutorial is available in PDF format and can be downloaded from various online sources.
3. FreeRTOS and ESP32/ESP8266 Microcontrollers by Neil Smyth: This tutorial focuses on using FreeRTOS with ESP32 and ESP8266 microcontrollers. It's available in PDF format and covers topics such as setting up the development environment, creating tasks, and using FreeRTOS APIs.

Mastering the FreeRTOS Real Time Kernel - A Hands-On Tutorial Guide by Richard Barry. Top Recommended PDF Resources Mastering the FreeRTOS Real Time Kernel Mastering the FreeRTOS Real Time Kernel - A

FreeRTOS (Free Real-Time Operating System) is an open-source, market-leading kernel designed for microcontrollers and small microprocessors including a user manual