Add support for LilyGo T3 with SX1276 module

- Add custom partition table for fitting larger firmware
- Create LilyGoT3S3Board.h for board-specific functionality
- Update all example files to support the T3 board with SX1276
- Configure build environment for optimizing firmware size
- Set up the right pin configuration for SX1276 on LilyGo T3

src/helpers/LilyGoT3S3Board.h

@@ -0,0 +1,88 @@
+#pragma once
+
+#include <Arduino.h>
+#include "ESP32Board.h"
+#include <driver/rtc_io.h>
+
+// LoRa radio module pins for LilyGo T3S3
+// These need to be defined here for the SX1276 version
+#if defined(RADIO_CLASS) && defined(CustomSX1276)
+  // SX1276 pin definitions specific to LilyGo T3S3
+  #define P_LORA_DIO_0   34    // DIO0 interrupt pin (SX1276 uses DIO0)
+  #define P_LORA_DIO_1   33    // DIO1 interrupt pin
+  #define P_LORA_NSS     7     // Chip select
+  #define P_LORA_RESET   8     // Reset pin
+  #define P_LORA_SCLK    5     // SPI clock
+  #define P_LORA_MISO    3     // SPI MISO
+  #define P_LORA_MOSI    6     // SPI MOSI
+#endif
+
+// Base class for LilyGo T-series boards
+class LilyGoTBoard : public ESP32Board {
+public:
+  void begin() {
+    ESP32Board::begin();
+
+    esp_reset_reason_t reason = esp_reset_reason();
+    if (reason == ESP_RST_DEEPSLEEP) {
+      long wakeup_source = esp_sleep_get_ext1_wakeup_status();
+      if (wakeup_source & (1 << P_LORA_DIO_1)) {  // received a LoRa packet (while in deep sleep)
+        startup_reason = BD_STARTUP_RX_PACKET;
+      }
+
+      rtc_gpio_hold_dis((gpio_num_t)P_LORA_NSS);
+      rtc_gpio_deinit((gpio_num_t)P_LORA_DIO_1);
+    }
+  }
+
+  void enterDeepSleep(uint32_t secs, int pin_wake_btn = -1) {
+    esp_sleep_pd_config(ESP_PD_DOMAIN_RTC_PERIPH, ESP_PD_OPTION_ON);
+
+    // Make sure the DIO1 and NSS GPIOs are hold on required levels during deep sleep 
+    rtc_gpio_set_direction((gpio_num_t)P_LORA_DIO_1, RTC_GPIO_MODE_INPUT_ONLY);
+    rtc_gpio_pulldown_en((gpio_num_t)P_LORA_DIO_1);
+
+    rtc_gpio_hold_en((gpio_num_t)P_LORA_NSS);
+
+    if (pin_wake_btn < 0) {
+      esp_sleep_enable_ext1_wakeup( (1L << P_LORA_DIO_1), ESP_EXT1_WAKEUP_ANY_HIGH);  // wake up on: recv LoRa packet
+    } else {
+      esp_sleep_enable_ext1_wakeup( (1L << P_LORA_DIO_1) | (1L << pin_wake_btn), ESP_EXT1_WAKEUP_ANY_HIGH);  // wake up on: recv LoRa packet OR wake btn
+    }
+
+    if (secs > 0) {
+      esp_sleep_enable_timer_wakeup(secs * 1000000);
+    }
+
+    // Finally set ESP32 into sleep
+    esp_deep_sleep_start();   // CPU halts here and never returns!
+  }
+
+  uint16_t getBattMilliVolts() override {
+    analogReadResolution(12);
+
+    uint32_t raw = 0;
+    for (int i = 0; i < 8; i++) {
+      raw += analogReadMilliVolts(PIN_VBAT_READ);
+    }
+    raw = raw / 8;
+
+    return (2 * raw);
+  }
+};
+
+// Standard ESP32 version (for T3 board)
+class LilyGoT3Board : public LilyGoTBoard {
+public:
+  const char* getManufacturerName() const override {
+    return "LilyGo T3";
+  }
+};
+
+// For S3 variant
+class LilyGoT3S3Board : public LilyGoTBoard {
+public:
+  const char* getManufacturerName() const override {
+    return "LilyGo T3S3";
+  }
+};