A simple solution to prevent a solar powered LoRaWAN gateway from going into brownout when the batteries drop in voltages.
I have a solar powered Raspberry Pi + RAK2245 + RAK2013 that has a problem where when it gets cold out, the batteries don't have the Amps to power the gateway when the sun comes up. This puts the gateway into a brownout state where the cellular module disconnects and will not reconnect until the system is rebooted.
I have learned that a few minutes delay will resolve this issue, allow the batteries to charge and the system to boot correctly. This project is an attempt to automate this task.
When the voltage drops below about 3 volts, the MCP102-300E/TO will sit it's pin 2 LOW, once the voltages has stablized above 3 volts for more then 120 ms, pin 2 goes HIGH.
The PIC16F15214-I/P microcontroller reads the input from pin 2 on the MCP102-300E/TO (via pin 2 [INT] on the microcontroller) and set pin 0 LOW. When microcontroller pin 0 is LOW, the PN2222A disables the power to the output pins of the board.
- KiCad EDA - Version 6.0.2 - The Schematic & Board softare
- MPLAB X IDE - Version 6.0.0 - Software used to build the C code
- XC8 - Version 2.32 - The C compiler (A part of MPLAB X IDE)
| Identifier | Qty | Part # | Description | DigiKey |
|---|---|---|---|---|
| U1 | 1 | PIC16F15214-I/P | Microcontroller | 150-PIC16F15214-I/P-ND |
| Q1 | 1 | PN2222A | Transistor | PN2222AFS-ND |
| Q2 | 1 | MCP102-300E/TO | Voltage Supervisor | MCP102-300E/TO-ND |
| C1 | 1 | 10pF | Ceramic Capacitor | K100K15C0GF53L2-ND |
| D1 | 1 | 1N914 | Diode | 1N914FS-ND |
| RV1 | 1 | PV36W103C01B00 | 10K Ohm Trimmer | 490-2875-ND |
| SW1 | 1 | 1825910-6 | Push Button - 6mm | 450-1650-ND |
The Top of the Board
The Bottom of the Board
