Solar Powered Low Cost LoRa Node with Integrated Battery Holder


(Arinze Izukanne) #1

I wish to share my designs for a multipurpose LoRa microcontroller board based on the Atmel 328P microcontroller with an RFM95W LoRa module attached and LiPo Battery holder mounted on the reverse side of the board. Details of the design including PCB and BOM are available here.

The version 2, design details available here, adds onboard solar power LiPo charger for the integrated 18650 LiPo battery, using the CN3065. The idea is to provide a Low Cost LoRa module that makes all digital and analog inputs of the Atmel 328P available. This node can be used for prototyping. The board runs on 3.3V and the regulator on board is the MCP1700T-3302E/TT. No power LED is provided to reduce power consumption but an LED is connected to D7 via a 1K resistor.

If you plan to implement this project, remember to flash a bootloader unto the controller. Usually, I do this after the controller has been soldered on the board but before the LoRa module is welded on. This allows you to use the pads where the LoRa module should be to connect to the SPI bus of the controller for flashing.

Below are pictures of the finished version 1. Version 2 boards are currently in production.

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Feedback and suggestions for improvement are welcome.


(Mt) #2

Good Work.


(Lhanneus) #4

I do this after the controller has been soldered on the board but before the LoRa module is welded on.

Is it possible to flash the bootloader aftersoldering the RFM95 ?


(Arinze Izukanne) #5

In my experience, I doesn’t work. The SPI bus doesn’t respond correctly with more than one device on it.


#6

It’s possible, but you need to PullUP SS!
[ISP%26PullUp
ISP%26PullUp


(Arinze Izukanne) #7

Cool. Thanks for this info.


(Arinze Izukanne) #8

Here are some pictures of the Version 2 board, which includes connection for a 6V solar panel and solar charging for a LiPo battery using the CN3065. All unused analog and digital pins are exposed and there are connectors for 3.3V and GND on board. This allows connection of multiple sensors directly to the board. The LoRa module used if the RFM95W.

When encased, we will be using multiple nodes like this to monitor motion and environmental conditions in different locations within a city. I hope people will come up with other more creative applications.

Here are some photos…

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