Hi everyone,

This is a low-power LoRa weather station PCB I've been designing and I'd appreciate a review before ordering boards.

# Overview

The design is built around:

* STM32L052C8T6 MCU
* SX1262 LoRa transceiver (bare chip, not a module)
* LP25HB barometric pressure sensor
* SHT40 temperature/humidity sensor
* GD25Q32 external flash
* AP2112K 3.3V regulator
* 32 MHz RF crystal for SX1262
* 4-layer PCB

# PCB Stackup

Current stackup:

1. Signal
2. Ground
3. Ground
4. 3.3V / Signal

The board is intended for very low-power operation, spending most of its life in sleep and periodically waking up to collect environmental data and transmit it over LoRa.

# RF Section

The SX1262 is connected to a 50 Ω RF trace leading to the antenna.

Current RF design includes:

* Grounded coplanar waveguide
* 50 Ω controlled impedance trace
* Matching network footprint
* RF stitching vias around the RF section
* Dedicated ground under the RF path

# Power

The system is designed for battery operation and aggressive sleep modes.

Planned operation:

1. Wake up periodically
2. Read sensors
3. Store data if needed
4. Transmit packet over LoRa
5. Return to sleep

# Things I'd Like Feedback On

# RF Layout

* Is the SX1262 RF layout reasonable?
* Are there enough stitching vias around the RF section?
* Is the antenna feed and matching network placement acceptable?
* Any obvious RF mistakes before fabrication?

# Power

* Any issues with the AP2112K implementation?
* Anything that could significantly increase sleep current?
* Any recommendations for reducing power consumption further?

# Sensors

* Is the SHT40 and LP25HB placement appropriate?
* Should more copper be removed around it?
* Any concerns regarding pressure sensor placement or venting?

# SPI Flash

* Any issues with using GD25Q32 alongside the STM32L0?
* Are IO2 and IO3 best left with high or handled differently?

# General Review

* Any schematic mistakes?
* Any layout mistakes?
* Anything that looks suspicious before I send it for manufacturing?
* Anything I need to keep in mind when sending for manufacturing?

GitHub, schematics, PCB screenshots, and KiCad files are attached.

Thanks for taking a look!  
[https://kicanvas.org/?repo=https%3A%2F%2Fgithub.com%2Fsouptik-samanta%2FSensor-Node%2Ftree%2Fmain%2FPCB](https://kicanvas.org/?repo=https%3A%2F%2Fgithub.com%2Fsouptik-samanta%2FSensor-Node%2Ftree%2Fmain%2FPCB)

[https://github.com/souptik-samanta/Sensor-Node](https://github.com/souptik-samanta/Sensor-Node)

[Review Request] STM32 + SX1262 LoRa Weather Station