Goal: Design and develop an open-sourced microcontroller with radio communication capabilities.

While there are a number of microcontrollers with implemented radio frequency modules, there are very few open-sourced options available. This project aims to change that with the creation of an open-sourced version of a radio microcontroller, while providing documentation across the different analog and digital design implementations that were chosen for this project.

Problem Statement:

Many radio microcontroller units (MCUs) exist on the market today; however, their designs are closed source. This makes it difficult for users of radio MCUs such as the ISU ChipForge co-curricular, faculty, and radio hobbyists to learn about radio microcontrollers without reverse engineering the unit due to the designs not being publicly available. It is important that they learn about radio communication now as wireless connections are becoming more common compared to their wired counterparts. To address this, our team is designing an open-source radio MCU. This will provide anyone who desires to learn about how a radio MCU works with all the documentation and implementation details, including how we designed and implemented in our unit. In addition, our implementation can be fabricated through the Efabless Corporation, which allows users to physically use and analyze the radio MCU on top of being able to look at design documents. Having this radio MCU be open-source enables users to make their own modifications to the design, which is something an individual cannot do with closed source units. This further promotes learning and creates opportunities for individuals to be innovative with the base radio MCU design.

Project Requirements:

• Microcontroller is developed using the Efabless Caravel Platform
• Microcontroller should be programmable
• Has to implement Zigbee Protocol
• Necessary to support lower frequency
• Contains standarrd peripherals
• UART, I2C, SPI, Timers
• All applied materials and documentation will be open-sourced

What is Efabless and Caravel?

Efabless is a creator platform that provides open-source chip design tools for developers to build and fabricate custom made chips. The Caravel platform is the development framework that Efabless utilizes to for prototyping. The platform includes a "User Project Area" that acts as a region where developers can create their own original custom designs. The rest of the chip infrastructure, such as I/O, power management, and standard components is pre-implemented to simplify the design process.

Caravel itself provides a fully function pre-configured system-on-chip (SoC) that includes an SPI (Serial Peripheral Interface) for communication, a management core for interfacing with user projects, standard analog/digital pads, programmable I/Os, and clocking circuits.

Who does this project benefit?

This project's design is ultimatley meant to be utilized for ISU's ChipForge club, which is a co-cirriculuar focused on IC design that is open to all experience levels, both ungraduate and graduate. The documentation this project will provide will help provide a solid foundation for newer club members on board bringup and testing, and serve as a learning experience with insights into the Efabless process and the chip creation process. Given that this is the first microcontroller project for this club that attempts to fabricate analog components of a radio, this projects will provide major insight into radio implementations at a low-level for future students and club memebers to learn from.

This project will also benefit faculty who may want to use this project in lab environments to give students an opportunity to experiment and work hands-on with an open-sourced radio microcontroller to teach and show students how what is being taught in class can be applied to real projects.

Radio hobbyists could also potentially use our project, as good documentation and tooling allows for ease to use and creates an environment for creative expression. Given that our microcontroller will be open-sourced, this also provides a platform for other enthusiasts to take our project into different avenues of experiementation down the line.

Designing the Microcontroller

For details on how the userspace is being utilized for this project, please see the design document below which entails both minimal and full design implementations, along with the rationale behind our respective design choices.