This page is a work in progress!
This LORA-GPS-Tracker was designed to just test three modules, which I haven't worked with yet: the RFM95 LORA module, the ESP32-S2-Mini module and the ATGM336h GPS module. All combined this device can be used as a GPS-Tracker for LORA based systems. Additionally to the modules, the board includes a 0.96" OLED display, two user buttons, a user RGB LED, a LiPo battery charger with a 16340 cell holder, and a dual LDO setup, which is very handy when it comes to deep sleeping.
Here are some specs of the board:
- ESP32-S2-Mini
- USB Type-C for charging the battery and flashing the ESP32
- Dual LDO setup, which will reduce the sleep current (the main power sinks can be shut down before entering a sleep mode)
- Power friendly OLED display
- Dimensions are 60x43mm
The Youtube Video shows the PCB assembly process, some initial tests and some power measurements.
The RFM95 LORA module is connected via SPI, the ATGM336h GPS module is connected via UART and the OLED display is connected via I2C.
| GPIO ESP32 | Function | Mode |
|---|---|---|
| GPIO1 | LORA_RST | Output |
| GPIO2 | LORA_MISO | Input |
| GPIO3 | LORA_MOSI | Output |
| GPIO4 | LORA_SCK | Output |
| GPIO5 | LORA_CS | Output |
| GPIO6 | LORA_INT | Input |
| GPIO7 | LORA_DIO1 | Data |
| GPIO8 | LORA_DIO2 | Data |
| GPIO12 | Button2 | Input |
| GPIO14 | Enable LDO2 | Output |
| GPIO15 | BAT_ADC | Input |
| GPIO16 | Button1 | Input |
| GPIO19 | USB_DN | Data |
| GPIO20 | USB_DP | Data |
| GPIO34 | OLED_RST | Output |
| GPIO35 | I2C_SCL | Output |
| GPIO36 | I2C_SDA | Data |
| GPIO37 | LED_CLK | Output |
| GPIO38 | LED_SDI | Data |
| GPIO40 | GPS_PPS | Input |
| GPIO41 | GPS_RXD | Input |
| GPIO42 | GPS_TXD | Output |
By switching off the EN_LDO2 output, the second LDO which powers the GPS as well as LORA module, the onboard LED and the OLED display, will be shut down.
| State | Avg. current | Peak current |
|---|---|---|
| Reading sensors | 80mA | 92mA |
| Transmitting LORA | 135mA | 208mA |
| Deep sleep | 75µA | 82µA |
Note: The schematics in this repo have the I2C pull-up resistors connected to +3V3. It reduces the power consumption if you don't mount these resistors or if you connect them to VDD (controllable via LDO2).