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A project log for SoLoRa - Solar Powered always-on IoT sensor node

Unique, compact power conditioning enables always-on sensor monitoring and Long-Range radio (LoRaWAN) link for IoT applications.

Joe MillerJoe Miller 07/24/2018 at 19:240 Comments

First (full) power budget spreadsheet completed and added this project. This spreadsheet, tailored to the SOLoRa board, is a vital design tool to properly analyze all aspects of a system design for always-on IoT node with intermittent power harvesting input.  In my initial feasibility study I performed notebook calculations with a mix of early empirical data and best estimates. This spreadsheet's calculations, and the data contained within, more accurately models the actual circuit performance.  The microcontroller's sleep current is much higher than I like so I will continue working on reduce it. Even with the 500uA sleep current, as shown, my power budge is feasible.  The input parameters of the budget worksheet shown below uses conservative settings for Spreading factor (10), with 7 being the lowest power consumption. The output power is also set to 20dBm, the maximum. After site testing, one could lower these values to increase budget margins.

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