TTGO LoRa32-OLED V1.0 Pin Mapping

Hardware configuration for TTGO LoRa32-OLED V1.0 board (ESP32 + SX1276/SX1278 LoRa + 0.96" SSD1306 I2C OLED).

Source

Pin mapping cross-checked against the TTGO example sketch here:

• https://raw.githubusercontent.com/sfambach/esp32/refs/heads/master/boards/TTGO_LoRa32-Oled/src/TTGO_Examples/OLED_LoRa_Receiver/OLED_LoRa_Receiver.ino

LoRa (SX1276/SX1278)

These pins are used for SPI + control:

• SCK = GPIO5
• MISO = GPIO19
• MOSI = GPIO27
• CS/NSS/SS = GPIO18
• RST = GPIO14
• DIO0 (IRQ / RxDone) = GPIO26

In this repo these correspond to the compile-time config:

• LORA_SCK=5
• LORA_MISO=19
• LORA_MOSI=27
• LORA_CS=18
• LORA_RST=14
• LORA_DIO0=26

Notes

• DIO0 is on GPIO26, which is an RTC-capable GPIO on ESP32. That means it can be used as a wake source in some sleep modes.

OLED (SSD1306 I2C)

• SDA = GPIO4
• SCL = GPIO15
• RST = GPIO16

In this repo these correspond to:

• OLED_SDA=4
• OLED_SCL=15
• OLED_RST=16

Interactive OLED Menu System

Both sender and receiver now feature an interactive menu controlled via GPIO0 (the boot button on TTGO LoRa32).

Button Behavior

Visual Feedback

• Progress bar: While holding button, a progress bar fills on line 5 showing how long until activation
• Invert flash: Brief inverted display flash (150ms) confirms item activation
• Pagination: Menu items paginate (4 per page) with page indicator

Menu Items

1. START - Starts heating with last-set duration (default 30 min)
2. STOP - Stops heating
3. RUN 10min - Starts heating for 10 minutes
4. RUN 20min - Starts heating for 20 minutes
5. RUN 30min - Starts heating for 30 minutes
6. RUN 90min - Starts heating for 90 minutes

Sender Menu Behavior

• Sends LoRa command to receiver
• Waits for acknowledgment (shows "Waiting ACK" on OLED)
• Preset duration is remembered and used by START command
• OLED shows status view normally, menu replaces status when opened

Receiver Menu Behavior

• Sends W-BUS command directly to heater
• Immediate W-BUS response updates heater state
• Preset duration is remembered for next menu activation
• OLED shows status view normally, menu replaces status when opened

OLED Display Modes

Status View (normal, menu hidden)

Webasto LoRa Sender        | Receiver heating status
Preset: 30min | 12.5V      | showing W-BUS state
OFF          5s ago        | Last command: 120s ago
50°C  13.2V  2200W         | Operating state: 0x05
RSSI: -95dBm SNR: 8dB      | Power: 2200W
Waiting for status...      | Temperature: 65°C

Menu View (menu visible)

=== MENU ===

> START
STOP
RUN 10min
RUN 20min

Long press to activate

Implementation Files

• New files: lib/common/menu_handler.h, lib/common/menu_handler.cpp
• Modified: src/sender/main.cpp, src/receiver/main.cpp, include/project_config.h
• Config: MENU_BUTTON_PIN defined as GPIO_NUM_0 in project_config.h

Button-Free Alternative

If you don't want interactive menus, the devices still work with serial commands:

• Sender: Serial input parses commands (start, stop, run N)
• Receiver: Responds to LoRa commands without requiring button interaction

Concept: Battery Power & 10-Second Command Latency

Given that up to ~10 seconds of command latency is acceptable, the most battery-efficient approach is:

Sender (handheld)

• Default state: ESP32 deep sleep (almost always).
• Wake on button press.
• “Fire-and-forget” command transmit:
  • Send the command multiple times over ~10 seconds (or fewer times if receiver listen windows are more frequent).
  • Include a command seq/nonce and have the receiver deduplicate so repeated packets don’t re-trigger actions.
• OLED on only during user interaction, otherwise power-saved.

Receiver (heater side)

Two power modes:

1. Heater OFF / idle (dominant case)

• Use duty-cycled receive windows:
  • Wake periodically (timer) and listen for a short window (e.g. 200–300 ms every 5–10 s).
  • Keep the SX1276 in RX only during the window; put it to sleep otherwise.
• This yields very low average current and still catches a repeated sender command within the 10s latency budget.

2. Heater RUNNING

• Stay awake (or mostly awake) because you’re polling W‑BUS and reporting status.
• Per your requirement: keep the receiver OLED on while running.
• You can still reduce consumption by lowering OLED refresh rate and sleeping the radio between sends.

About IRQ wake (SX1276 DIO0 → ESP32)

• It is possible to wire/design a system where SX1276 DIO0 wakes the ESP32 (GPIO26).
• However, if you want the radio to wake the ESP32, the radio generally must be kept in RX (non-trivial current draw).
• With 10s acceptable latency, it is usually better to save power by sleeping both ESP32 and radio and relying on periodic RX windows + sender repeats.