RL78 Energy Harvesting/Scavenging

Hey Guys, 

Please find attached an Energy Harvesting Project developed using the RL78/G14 MCU. The Intention of the project was to construct a system capable of harvesting the waste energy produced by a Cup/Mug filled with a hot beverage. The harvested energy is then used to power a display mechanism(E-Ink) and a wireless communication module (WM-Bus). 

The attached file contains all of the documents relating to the project (Software source files, Hardware reference design and Application Notes). I would strongly recommend thoroughly reading the Application Notes prior to attempting any modifications to the design, as they describe the project in detail and outline areas of possible improvements. 

Have Fun Playing with it. 

Edson Da Silva

Student Intern 

  • No way, that’s awesome!

    RL78 is the microcomputer that is suitable for Energy Harvesting.

    Energy required for wireless communication about 100uJ(=100uW×1s).

    I also have used RL78 to energy harvesting by inverse magnetostrictive with vibration.

    Since my harvester was very very small, generated output was less than 10uW.

    Voltage goes up slowly as power outlet mounts large capacitor.

    Voltage remained stopping at about 1V, when connecting the harvester to direct RL78.

    It was OK when carrying out voltage supply to RL78 by power gating regulator, after the generated voltage exceeded 1.6V.

    Current characteristics of the RL78 is shown below.

    japan.renesasrulz.com/.../g13_5F00_current.gif

  • Hey Karin,

    Thanks For the post. Your information is very revealing I had the exact same problem.

    The energy generated by the Harvester was not sufficient to power the system between 1.1 and 1.6 volts.

    I had a suspicion that the initial start up current of the RL78 was the problem, but that diagram just answered all my doubts.

    Your project sounds awesome though :)    

  • Hi edson.da-silva,

    Thank you for your reply.

    Show you the result of measuring the current consumption of the other microcomputers.

    It's a Japanese page, but you can see the graphs.

    japan.renesasrulz.com/.../1178.aspx

    Interestingly, it is different for each microcomputer.