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https://github.com/peppson/radio-nodes

Solar/Battery/USB powered wireless "smarthome" modules.
https://github.com/peppson/radio-nodes

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Solar/Battery/USB powered wireless "smarthome" modules.

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README 

        



![flow_diagram](_images/header.png)



# radio-nodes



Solar/Battery/USB powered wireless "smarthome" modules, based on the Attiny824 microcontroller.  

Serves as the end-node of [MQTT-radio-gateway](https://github.com/Peppson/MQTT-radio-gateway).   

Written in C++ with PlatformIO.  



 

## Project Overview

- Each node is easily configurable to perform various tasks, such as watering plants,  

turn on the coffeemaker, opening blinds, relaying sensor data, etc. 



- Power consumption was the main concern when designing this.   

Nodes consumes ∼`2mA` @ 3.3V in active listening mode, and as low as ∼`3uA` @ 3.3V while deepsleeping!  

Making it possible to power some nodes indefinitely from a small solarpanel.  

Measured and optimized using [Power Profiler Kit II](https://www.nordicsemi.com/Products/Development-hardware/Power-Profiler-Kit-2).  



- This project was primarily made for personal ***"needs"***. But it is open for use by anyone who finds it beneficial.  

Every ***node*** has it's own directory inside `src` with it's own enviroment, selected from `platformio.ini`.



 

## Hardware and PCB  

Made a compact PCB integrating a [TP4056](https://www.amazon.com/TP4056/s?k=TP4056) Li-ion/LiPo battery charger, an [nRF24L01+](https://www.amazon.com/s?k=nRF24L01%2B&crid=1VM0GXMUG7ISX&sprefix=nrf24l01%2B%2Caps%2C145&ref=nb_sb_noss_1) radio,   

and the [Attiny824](https://www.mouser.se/ProductDetail/Microchip-Technology/ATTINY824-SSF?qs=pUKx8fyJudA6%2F%2FVSNIlI1w%3D%3D) AVR microcontroller.  



More images in: [📂 _images/](./_images/)  

KiCad files: [📂 _KiCad/](./_KiCad/)  



    Schematic

  



![schematic](_images/schematic_v3.png)  



    PCB layout 

     

    

> 2-layer PCB, dimensions 42mm x 31mm.  

> The PCB has 3 sections, configurable based on the node.

> - ***BAT or USB:*** Battery or USB/5V driven.  

> - ***LOAD:*** Components for the "load driver circuit".  



![PCB_layout](_images/PCB_layout_v3.PNG)  

  



    Power consumption in active mode 

  



> In active mode, the node toggles its radio `on` for 50ms and `off` for 950ms to minimize power usage,    

> halting the CPU between pulses.  

>

> Resulting in an average power draw of ∼2mA @ 3.3V.  



![PCB_layout](_images/node_active_power_draw.PNG)  



    Programming

  



The ATtiny 2-series MCUs have [UPDI](https://onlinedocs.microchip.com/pr/GUID-F626284A-58F0-4C25-A6F3-0EA5054F3E2B-en-US-6/index.html?GUID-D25E0E3F-4FC2-454B-8A2D-C52EAA4EBE81) interface. Which makes it possible to program with only 1 data pin!  

You can see the UPDI pins at the bottom of the PCB. 



I created a simple DIY programmer using an Arduino Nano, to help with uploading firmware.   

More details here [UPDI programmer](https://github.com/Peppson/simple-UPDI-programmer).



  

    

### PCB

  ![hardware](_images/PCB_rendered_v3.PNG)  



### Hardware

> With and without the TP4056 and nRF24L01+ modules. Dimensions 42mm x 31mm.  

> The picture shows a battery/solar-powered node.



![hardware.jpg](_images/hardware.jpg)  



 

## Nodes 



    Nodes 1-10: Self watering plants  



  

Uses a 3-5V waterpump and DIY capacative fluid-level sensor.  See link below.  

[Liquid Level Sensing Using Capacitive-to-Digital Converters](https://www.analog.com/en/analog-dialogue/articles/liquid-level-sensing-using-cdcs.html)  



The solar-powered variant uses the TP4056 to charge a Li-ion/LiPo battery.  

While the USB variant skips that step and plugs directly into 5V (with 3.3V LDO onboard).  



#### Node 1 water sensor linearity:    



> Sensor (ADC) reading vs water level in %. 



![water sensor](_images/Node_1_water_sensor_example.PNG)



#### Node 1 hardware:  



> Most of the self-watering plant nodes have the hardware inside a plastic enclosure,   

> which I just hide behind the pots.  

> However, for node 1, I placed all electronics underneath for a pretty decent look.   



![node_1_hardware.jpg](_images/node_1_hardware.jpg)

   



 



    

        Node 11: Mocca Master controller

    



Uses a SG90 servo mounted internally to toggle the `On/Off` button,   

and a hall-effect current sensor, to get the current state.

  

> "Looks pretty neat when the button toggles all by itself :)"