LoRa GPS lost model finder, this is the device with integrated:
- RFM96 LoRa module,
- GPS BN-180 driven via MOSFET for better power consumption management,
- Arduino promini 8MHz with upgraded voltage regulator and updated bootloader,
- 150mAh lipo 1S.
The basic purpose of the module is to get the valid GPS fix and send this over the LoRa mod, so it can be possible to track this device from the longer distance.
Attaching this module to the RC model can help to track down the model in case of the "not planned landing" somewhere in the field. Once the module is energised, it will try to get the GPS fix. It will also make the short beep each 15 sec. Each 5min it will send the coordinates and status over the LoRa module. Once the GPS fix is solid, the module will deactivate the GPS for 4min to save the energy. With such energy schema, the device can work for up to 7hours, beeping each 15seec and sending the LoRa message each 5min. The distance is the outcome of many factors. I use the max power of RFM96, SF12, 125kHz, the best codng and the highest (allowed) power, hoping that even in the worst condition I will be able to pick up the signal.
The whole electronic is put into 3D printed housing with the dimension of: 46x19x21mm.
The whole device, as on the pics weights 21gr.
The antenna is fine tuned to the 868MHz.
The device is designed to be completely standalone, but it would be wise to connect it to the power in the model during the long range flies - as the secondary power supply and to prolong the battery for the "after crash" when, mostlikely, the main battery will disconnect from the model.
The tests in the field with the GPS antenna pointed down confirms that there is no problem to get the fix within 15sec.
The hex file is attached, the pins for the sender are:
'#define pin_Buzzer A1
'#define pin_Voltage_input A2
'#define pin_GPS_power 6
GPS TX connected to RX of pro mini.
LORA connected to SPI of promini, with CS on pin 10 and reset on A0.
The receiver is for this unit is here:
Enjoy on your own risk.