• 02
    Jul - 2017

    Android Things
    3 min | 304

    #ProjectDIVA: PiCoBo Rev1.1

    Android Things | 3 min | 304


    android things
    dehumidifier
    dh11
    nrf24l01
    pcb design
    picobo
    raspberry pi
    smart sensor

    Hi there!

    I had some humidity problems in the basement and I thought I can buy a dehumidifier. I bought this one on ebay Dehumidifier 500ml. I knew they are not good enough, but I wanted to try.

    This type of dehumidifier uses a peltier element to cool an alumium disipator (peltier cool side), which condenses the humidity. The condensed humidity drips into a water tank until it is full. Then, a switch is triggered and the system stops. The peltier hot side has a bigger disipator and together with a fan disipate the generated heat.

    C++  **Code:** https://goo.gl/CPGcYK
    Eagle  **Eagle:** https://goo.gl/xFcc24
    Android Things  **nRF24Things:** https://goo.gl/SNnhxq
    Dehumidifier Internal Photo
    Alumium disipator, which condenses the humidity & water tank

    I thought I could make it "smarter". I took one of my PiCoBo boards, which I designed in 2014 and soldered the parts. Now I have a dehumidifier, which can measure temperature and humidity, it has an USB connection and a nrf24l01+ module, which reports the measured values and the current states (on/off, water tank inside, water tank full etc.) to a raspberry pi. The last running Android Things!

    Here some pics of the PiCoBo (without nrf24l01+) Rev1.0:

    PiCoBo PiCoBo
    PiCoBo: MSP430G2553 side PiCoBo: Sensor (DHT11) & Mosfet side

    Inside the dehumidifier case it looks like this (fixed with "some" hot glue):

    PiCoBo
    PiCoBo glued to the dehumidifier

    PiCoBo is a multi-target board. I designed it using the MSP430G2553 (20/28 pin version), which is part of the MSP430 Texas Instruments family of ultra-low-power microcontrollers. The board includes a CP2102 which can be used for communication over UART -working at baud rate of 9600. The board can be supplied using a C2032 battery, over USB or external DC source up to 10V. It uses a TPS77301DGK to regulate the max. voltage of 3.6V needed for the MSP430. Up to three IRLL2705 can be soldered to the board to switch on/off directly (or using PWM) voltages up to 55V and 3.8A. Multiple pinouts are available to connect external sensors (e.g. DHT11), servo motors, leds etc. For testing uses it can be programmed using the MSP430G2553 LaunchPad.

    I used a DHT11 sensor, which has the following specifications. A good comparison between temperature & humidity sensors (some of them low cost) can be found on the following links:

    For the next designs, I will be using a DHT22.

    To sumarize, here you can find the main hardware and software components that were used in this project. I included some links to buy the hardware components from ebay or Texas Instruments.

    Hardware

    Dehumidifier Dehumidifier 500ml
    PiCoBo PiCoBo
    nrf24l01+ nrf24l01+
    DHT11DHT11
    MSP430G2553IPW28MSP430G2253IPW28   
    CP2102CP2102
    TPS77301DGKTPS77301DGK   
    TPD2E001DRLRTPD2E001DRLR   
    IRLL2705IRLL2705

    Software

    C++ Project Diva: PiCoBo
    Java Project Diva: nRF24Things
    Android Studio Android Studio > 2.2.3
    Eagle Cad Eagle Cad
    Android Things Android Things >= (0.)4.1

    All the codes and hardware designs that I publish in this blog have an Apache 2.0 license. They are complete free, but if you are consider supporting this project with a donation, here you can find a button!

    Thanks! and have a good one!

    PS: Good luck to all of you who are struggling with the washing machine in the basement.


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