LoRa GPS lost model finder - device in the model

thingiverse

LoRa GPS Module, a device that combines the following components: RFM96 LoRa module, BN-180 GPS driven by MOSFET for efficient power management, Arduino Pro Mini 8MHz with upgraded voltage regulator and updated bootloader, buzzer, and 150mAh Lipo 1S battery. The primary purpose of this module is to obtain a valid GPS fix and transmit it via the LoRa module, enabling tracking from a long distance. Attaching this module to an RC model allows for easy tracking in case of an unplanned landing. Once energized, the module attempts to acquire a GPS fix and emits a short beep every 15 seconds. Every five minutes, it transmits coordinates and status via the LoRa module. When a solid GPS lock is established, the module deactivates the GPS for four minutes to conserve energy. With this power management scheme, the device can operate for up to seven hours, emitting beeps every 15 seconds and transmitting LoRa messages every five minutes. Distance coverage depends on several factors; I utilize maximum RFM96 power, SF12, 125kHz bandwidth, optimal coding, and maximum allowable power to ensure signal reception even in adverse conditions. The entire electronic circuit is housed within a 3D printed enclosure measuring 46x19x21mm. The device's weight is 21 grams as seen on the pictures. The antenna is carefully tuned for operation at 868MHz frequency. This device is designed to be fully standalone, but it's wise to connect it to the model's power source during long-range flights to serve as a secondary power supply and extend battery life in case of an after-crash scenario when the main battery may disconnect from the model. Field tests have confirmed that the GPS antenna can acquire a fix within 15 seconds without issues. A hex file is attached for the sender, with pin definitions as follows: '#define pin_Buzzer A1', '#define pin_Voltage_input A2', and '#define pin_GPS_power 6'. The GPS TX is connected to the RX of Pro Mini, while LORA is connected to SPI of Pro Mini via CS on pin 10 and reset on A0. The receiver for this unit can be found at: https://www.thingiverse.com/thing:3577488. Use at your own risk.