Botoks

Botoks is a batteryless timekeeping sensor that operates intermittently harvesting ambient energy. Botoks's hardware and software components enable IoT applications that require precise and intermittency-safe timekeeping. Both hardware design and software stack are open-source.

The cascaded hierarchical remanence timekeeper (CHRT) embedded on Botoks is a novel remanence timekeeper architecture. In principle, capacitive remanence timekeepers are simple RC circuits whose energy level is converted into time. To know more about them and the CHRT, refer to our paper (to be made public) and the docs.

The sensor is based on an MSP430 ultra-low-power, FRAM-enabled microcontroller (MSP430FR5994), and currently the software stack only supports this MCU.

Project Layout

apps/               ## Applications' source code
bin/                ## Compiled applications
config/             ## Various configuration files
docs/               ## Source documentation
external/           ## MSP430 base drivers
libs/               ## Core Botoks's libraries
platforms/          ## GPIO pin mappings
scripts/            ## Botoks's calibration scripts

Usage

Botoks's code can be built installing the MSP430-GCC toolchain, or using a preconfigured Docker container. Opting for the Docker container has the advantage of not having to install the toolchain, but requires you to mount the directory of the project into the container.

Executables can be uploaded and debugged using UniFlash or Code Composer Studio (CCS). The former method is easier to script, whilst the latter gives you access to a graphical IDE.

The following versions of CMake, MSP430-GCC and UniFlash were tested, but other versions might work as well.

Software	Version
CMake	3.13	download
MSP430-GCC	8.3.0	download
UniFlash	5.2.0	download

Building with the Docker container

You can use the build_with_docker.sh script to build all applications inside a Docker container. Install docker on your machine and start/enable the docker daemon. Moreover, make sure that you can docker commands without root privileges (check here). The script uses this Docker image to build applications inside a Docker container pre-configured with CMake and the MSP430-GCC toolchain.

You can pass -t <target> to the script to specify a target for make. For instance, to build all projects and install the generated executables in the bin/ folder of this repository, run

$ ./build_with_docker.sh -t install

Building without the Docker container

First of all, install CMake and the MSP430-GCC toolchain. CMake can be installed using your OS's package manager, though the latest version might not be available. In that case, download the binaries using the link above. As for the GCC toolchain, you can use the provided install_toolchain.sh script to download and install toolchain and support files.

To install, do

$ MSP430_GCC_OS=linux64   # can be 'linux32' or 'macos' instead
$ INSTALL_PREFIX=~/ti     # where to install the toolchain
$ ./install_toolchain.sh

This will download toolchain and other support files from TI's website, and install them at $INSTALL_PREFIX/msp430-gcc. Then, assign the environment variable MSP430_TOOLCHAIN_PATH the absolute path to the root directory of the toolchain, e.g.

$ export MSP430_TOOLCHAIN_PATH=~/ti/msp430-gcc

Finally, to build all projects, do

$ git clone https://github.com/TUDSSL/Botoks.git
$ cd Botoks
$ mkdir build && cd build
$ cmake ..
$ make

Then run make install to build all projects and install the generated executables in the bin/ folder of this repository. To build applications individually, run make <app-name>.

Running applications

First, connect Botoks to a debugger capable of debugging the MSP430 line of products. Then power Botox using the auxiliary power connector on the PCB. The voltage provided needs to be between 3.4 and 5V.

To upload an application install UniFlash. As of now, all scripts assume UniFlash is installed at /opt/ti/uniflash. From the project's directory root, run:

$ ./flash.sh bin/<app-name>.out

The serial output can now be monitored using your favorite serial monitor (e.g., picocom) with a baudrate of 19200.

$ picocom /dev/ttyACM1 -b 19200 --imap lfcrlf

Calibration

For the calibration procedure please refer to the docs. Running the calibration procedure requires a licensed version of MATLAB and the serial terminal picocom.

Documentation

The Docker container comes with all the dependencies to build the documentation. Simply run

$ ./build_with_docker.sh -t docs

and find the HTML documentation in build/docs/html.

Hardware

The hardware is designed in KiCad, however, PDF schematics and gerbers are available in the hardware folder.