Schematic Reading
Edit on GitHubReading the beacon's schematic: power rails, signal nets, and the five checks that catch wiring errors before soldering.
Schematic Reading
A schematic is a map of the circuit. This page teaches the beacon’s schematic in the terms that matter: rails, nets, and the five checks that catch most mistakes.
The layers of a schematic
| Layer | What it shows |
|---|---|
| Power rails | The 3.3 V and battery paths, regulators, decoupling |
| Signal nets | UART (GPS), I2C (OLED), SPI (radio), GPIO (buttons, LED) |
| Ground | The return path for everything |
The beacon’s nets
| Net | Pins | See |
|---|---|---|
| UART0 | ESP32 TX/RX to GPS | GPS Integration |
| I2C | SDA/SCL to OLED | OLED Display |
| SPI | MOSI/MISO/SCK/NSS to radio | E22 Module Pinout |
| GPIO | Buttons, LED, buzzer | GPIO Pin Map |
The five checks
Before soldering anything:
- Polarity: every electrolytic capacitor, diode and the battery: the + and - match the silkscreen.
- Power short check: with the multimeter, no continuity between 3.3 V and ground.
- Signal crossings: two signal nets must never share a pad; check the schematic, not the solder.
- Pull resistors: every button line has its pull (see Button System Details).
- The radio’s NSS: the chip-select line is unique to the radio; a shared NSS is a classic LoRa failure.
Reading symbols
- Ground: the stack of decreasing lines, the most important symbol on the page.
- Power: the labeled rail stub; find every instance of the 3.3 V symbol before tracing a fault.
- The SX1262’s pin names come straight from its datasheet (see Datasheet Reading).
Related pages
- Circuit Description for the project’s circuit
- GPIO Pin Map for the pin table
- Datasheet Reading for the module datasheets