Add Heltec WiFi LoRa 32 V3 support and generic display reset

platformio.ini

@@ -663,6 +663,28 @@ board_build.partitions = ${esp32.default_partitions}
 board_build.f_flash = 80000000L
 board_build.flash_mode = qio
 
+[env:heltec_wifi_lora_32_v3]
+;; Heltec WiFi LoRa 32 V3 - ESP32-S3FN8, 8MB flash, NO PSRAM
+;; IMPORTANT: BOARD_HAS_PSRAM must NOT be set on this board.
+;; This board has no PSRAM. Setting BOARD_HAS_PSRAM causes the DMA/memory allocation
+;; libraries to reserve memory only in SPIRAM (which doesn't exist on this board),
+;; resulting in Error 8 (memory depleted) at boot. See: esp32s3dev_4MB_qspi_hub75 for
+;; a similar pattern of handling ESP32-S3 boards without PSRAM.
+;; Display: onboard 0.96" SSD1306 128x64 I2C OLED (SDA=GPIO17, SCL=GPIO18, RST=GPIO21)
+;; Vext power rail for OLED: set GPIO36 LOW in display usermod via -D HELTEC_VEXT_PIN=36
+extends = esp32s3
+board = heltec_wifi_lora_32_V3
+build_flags = ${common.build_flags} ${esp32s3.build_flags}
+  -D WLED_RELEASE_NAME=\"Heltec_WiFi_LoRa_32_V3\"
+  -D WLED_WATCHDOG_TIMEOUT=0
+  -D ARDUINO_USB_CDC_ON_BOOT=0
+  -D ARDUINO_USB_MODE=1
+board_build.partitions = ${esp32.large_partitions}
+board_upload.flash_size = 8MB
+board_upload.maximum_size = 8388608
+board_build.f_flash = 80000000L
+board_build.flash_mode = qio
+
 [env:esp32s3_4M_none]
 ;; ESP32-S3 with 4MB FLASH, no PSRAM
 extends = esp32s3

usermods/usermod_v2_four_line_display_ALT/readme.md

@@ -58,6 +58,20 @@ These options are configurable in Config > Usermods
 
 Note: the Four Line Display usermod requires the libraries `U8g2` and `Wire`.
 
+### Board-specific Build Flags
+
+Some boards require special initialization for I2C displays. Set these flags in your `platformio_override.ini` (do not edit the main `platformio.ini`):
+
+* `FLD_PIN_RST` - GPIO pin for display hardware reset (optional)
+  * Performs a reset pulse before I2C initialization
+  * Required on boards like Heltec WiFi LoRa 32 V3 (GPIO21)
+  * Example: `-D FLD_PIN_RST=21`
+
+* `HELTEC_VEXT_PIN` - GPIO pin to enable switchable OLED power rail (optional)
+  * Pulls the pin LOW before display init to enable power
+  * Required on boards where the OLED is powered via a switchable rail rather than always-on VCC
+  * Example: `-D HELTEC_VEXT_PIN=36` for Heltec WiFi LoRa 32 V3
+
 ## Change Log
 
 2021-10

usermods/usermod_v2_four_line_display_ALT/usermod_v2_four_line_display_ALT.cpp

@@ -215,6 +215,30 @@ void FourLineDisplayUsermod::sleepOrClock(bool enabled) {
 // gets called once at boot. Do all initialization that doesn't depend on
 // network here
 void FourLineDisplayUsermod::setup() {
+#ifdef HELTEC_VEXT_PIN
+  // Pull the Vext power rail enable pin LOW before display init.
+  // Required on boards like the Heltec WiFi LoRa 32 V3 where the OLED is
+  // powered via a switchable rail (GPIO36) rather than always-on VCC.
+  if (PinManager::allocatePin(HELTEC_VEXT_PIN, true, PinOwner::UM_FourLineDisplay)) {
+    pinMode(HELTEC_VEXT_PIN, OUTPUT);
+    digitalWrite(HELTEC_VEXT_PIN, LOW);
+    delay(5);
+  }
+#endif
+#ifdef FLD_PIN_RST
+  // Some boards require a hardware reset pulse on the display RST pin before
+  // I2C init (e.g. Heltec WiFi LoRa 32 V3 uses GPIO21). Set FLD_PIN_RST in
+  // your platformio_override.ini to enable this.
+  if (PinManager::allocatePin(FLD_PIN_RST, true, PinOwner::UM_FourLineDisplay)) {
+    pinMode(FLD_PIN_RST, OUTPUT);
+    digitalWrite(FLD_PIN_RST, HIGH);
+    delay(1);
+    digitalWrite(FLD_PIN_RST, LOW);
+    delay(10);
+    digitalWrite(FLD_PIN_RST, HIGH);
+    delay(10);
+  }
+#endif
   bool isSPI = (type == SSD1306_SPI || type == SSD1306_SPI64 || type == SSD1309_SPI64);
 
   // check if pins are -1 and disable usermod as PinManager::allocateMultiplePins() will accept -1 as a valid pin