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A CHEAP SOLAR POWERED STM32 ARDUINO NODE

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ABOUT THIS STORY


Posted on March 11, 2017



Intermediate
2 Hours

Introduction


After building a cheap Atmega32 Arduino node as described in this story:
https://www.thethingsnetwork.org/labs/story/build-the-cheapest-possible-node-yourself

I decided to build a similar node based on the STM32F103C8T6 boards you can buy on Ebay and other sources for about $ 2.00.

See e.g.
https://developer.mbed.org/users/hudakz/code/STM32F103C8T6_Hello/
for a board description.

The main advantages are:

  • Much more space for your program (most boards have 128K flash even when advertised as 64K)
  • 20K RAM
  • High speed 32 bit ARM Cortex-M3 processor up to 72Mhz

The main disadvantages are higher power usage and a slightly larger board, but you can switch to lower speeds (8Mhz) and activate sleep modes to safe power when running on a battery or solar panel.

It will use only 70μA while sleeping if you remove the power led and 12μA without the regulator.

You are the network. Let's build this thing together.