• Verify that all power connections are correctly made. For instance, the ESP32 module should have its VDD pin connected to 3V3.
• Ensure that ground (GND) connections are consistently tied together.

• Ensure that all critical components such as the LoRa module (U2), ESP32 (U1), voltage regulator (U3), and battery charger (U4) are correctly wired according to their datasheets.
• Check the reset connections for both ESP32 and LoRa transceiver.

• Make sure the I2C lines (SDA and SCL) are connected properly from the ESP32 to I2C devices.
• Verify SPI connections (MISO, MOSI, SCK, CS) for the LoRa transceiver and any other SPI peripherals.

• Ensure that any required pull-up or pull-down resistors are used where necessary (e.g., on the I2C lines).

• Power: U1 $VDD$ is connected to the 3V3 net, which is correct.
• Ground: Multiple ground pins are appropriately connected to the GND net.
• Key peripherals:
  • UART_TX $Pin 1$ and UART_RX $Pin 2$ are correctly connected.
  • SPI signals (MISO, MOSI, SCK, CS1) are properly connected to the LoRa module.
  • I2C signals (SDA, SCL) are defined.

• Power: U2 $3.3V$ is correctly connected to the 3V3 net.
• Ground: All ground pins on the LoRa module are properly tied to the GND net.
• SPI: Ensure that the wiring matches the datasheet.

• U2 $SCK$ should connect to the ESP32's IO18.
• U2 $MISO$ should connect to the ESP32's IO19.
• U2 $MOSI$ should connect to the ESP32's IO23.
• U2 $NSS$ should connect to the ESP32's IO4.

• Verify that U4 $BAT$ is connected to the voltage output you're expecting.
• Ensure that PROG pin is correctly set using R2.

• VIN, VOUT, GND connections are correct.

• Each switch net and its connections should be reviewed.

• Connect all SPI devices' MISO lines to the ESP32's MISO pin.
• Connect all SPI devices' MOSI lines to the ESP32's MOSI pin.
• Connect all SPI devices' SCK lines to the ESP32's SCK pin.

• Assign a unique GPIO pin for each SPI device’s CS line.

Cpp
#include <SPI.h>

// Define CS pins
const int CS1 = 4;
const int CS2 = 5;

void setup() {
  // Initialize SPI
  SPI.begin();

  // Set CS pins as output
  pinMode(CS1, OUTPUT);
  pinMode(CS2, OUTPUT);

  // Initially set CS pins high (inactive)
  digitalWrite(CS1, HIGH);
  digitalWrite(CS2, HIGH);
}

void loop() {
  // Select Device 1
  digitalWrite(CS1, LOW);
  // Perform SPI communication with Device 1
  SPI.transfer(0x00);  // Example, replace with actual communication
  digitalWrite(CS1, HIGH);  // Deselect Device 1

  // Select Device 2
  digitalWrite(CS2, LOW);
  // Perform SPI communication with Device 2
  SPI.transfer(0x00);  // Example, replace with actual communication
  digitalWrite(CS2, HIGH);  // Deselect Device 2

  delay(1000);  // Repeat every 1 second
}