LoRa Hardware

SX1262 wiring, power, and board notes for GhostESP LoRa

Heltec V3 / V3.2

Ship with ESP32-S3 + SX1262 + SX1262 TCXO + OLED on the same PCB. Board configs power the radio via Vext.

The onboard radio uses SCK GPIO9, MISO GPIO11, MOSI GPIO10, CS GPIO8, DIO1 GPIO14, BUSY GPIO13, and RESET GPIO12 on both V3 and V3.2.

  • Vext / VEXT power: GPIO drives the external 3.3 V rail for SX1262 and OLED. GhostESP asserts Vext at lora start and de-asserts it at lora stop.
  • Heltec V3.2 notes: same pins as V3 but with updated TCXO and corrected antenna switch. Use the Heltec V3.2 board config; V3 config also works but may log TCXO warm-up warnings. Battery voltage divider is on a different ADC channel — fuel gauge scaling differs.

SPI and optional SD on S3

Heltec V3 does not include an SD socket. If no external SD board is fitted, messages such as mosi not valid or Failed to find a free SPI host for SD mean the optional SD pins are not configured; they do not indicate a LoRa failure.

  • A following SX1262 ready line confirms that the radio initialized successfully.
  • For an external SD board, configure valid pins and either use a separate SPI host or the supported shared-bus wiring. Do not assign the SX1262 chip-select pin to the SD card.

Elecrow CrowPanel Advance 4.3 (Meshtastic wireless module)

Use the sdkconfig.crowpanel_advance43 profile with the Elecrow SX1262 wireless module. Before powering the panel, set the rear function switch to 01 (WM). This routes the shared connector to the wireless module; TF/SD is not available in this mode.

The profile matches Elecrow/Meshtastic wiring: SPI SCK=GPIO5, MISO=GPIO4, MOSI=GPIO6, NSS=GPIO0, DIO1=GPIO20, BUSY/DIO2=GPIO2, and RESET=GPIO19. The module’s DIO3 TCXO is configured for 3.3 V. After flashing, run lora start, then confirm SX1262 ready and use lora status/lora diag.

Expected ready-log suffix: pins=6/4/5/0 irq=20 busy=2 rst=19 tcxo=0x07.

Elecrow CrowPanel Advanced P4 7/9/10.1 (Meshtastic wireless module)

Use sdkconfig.crowpanel_advanced_p4_mipi_1024x600 (v1.2+) or sdkconfig.crowpanel_advanced_p4_mipi_1024x600_v11 (v1.1) with the Elecrow SX1262 module in the wireless socket. The module shares the SPI3/GPIO27/28 expansion path with the optional nRF24 and UART passthrough, so only one of those functions can be enabled per build.

The socket follows Elecrow’s RADIO_GPIO_* defines: SPI SCK=GPIO8, MISO=GPIO7, MOSI=GPIO6, NSS=GPIO10, and BUSY=GPIO9. DIO1/RESET are GPIO27/28 on v1.2+ boards or GPIO53/54 on v1.1. The module’s DIO3 TCXO is configured for 3.3 V. Unlike the S3 Advance boards, the onboard C6 SDIO (GPIO14-19) and the microSD (SDMMC GPIO39/43/44) use separate pins, so Wi-Fi/BT and SD stay available while LoRa is running. The profile also parks the default GhostLink UART pins (TX GPIO6 / RX GPIO7) so boot never claims the radio’s MOSI/MISO. After flashing, run lora start, then confirm SX1262 ready and use lora status/lora diag.

Expected ready-log suffix (v1.2+): pins=6/7/8/10 irq=27 busy=9 rst=28 tcxo=0x07. Expected ready-log suffix (v1.1): pins=6/7/8/10 irq=53 busy=9 rst=54 tcxo=0x07.

Elecrow CrowPanel Advance 2.4 / 2.8 (wireless module)

Use sdkconfig.crowpanel_advance24 or sdkconfig.crowpanel_advance28 with the Elecrow SX1262 module attached. The firmware drives the module-select pin during lora start; these small-panel profiles keep the display on SPI2 and reserve SPI3 for the radio, so SD/TF is intentionally skipped while LoRa is enabled.

The factory wireless-module wiring is SCK=GPIO10, MISO=GPIO9, MOSI=GPIO3, NSS=GPIO0, DIO1=GPIO1, BUSY=GPIO46, RESET=GPIO2, with GPIO45 driven LOW to select the module. The module uses a 3.3 V DIO3 TCXO. Expected ready-log suffix: pins=3/9/10/0 irq=1 busy=46 rst=2 tcxo=0x07.

Custom board Kconfig pins

For a generic SX1262 on any ESP32, wire via custom board wiring and set:

CONFIG_HAS_LORA=y
CONFIG_LORA_NSS_PIN=<gpio>
CONFIG_LORA_SCK_PIN=<gpio>
CONFIG_LORA_MOSI_PIN=<gpio>
CONFIG_LORA_MISO_PIN=<gpio>
CONFIG_LORA_RST_PIN=<gpio>
CONFIG_LORA_BUSY_PIN=<gpio>
CONFIG_LORA_DIO1_PIN=<gpio>
CONFIG_LORA_VEXT_PIN=<gpio or -1 if not used>
CONFIG_LORA_ENABLE_PIN=<gpio or -1 if a module-select pin is used>
  • DIO1 / BUSY / RESET are mandatory; DIO2/DIO3 are driven by driver for TCXO/RF switch.
  • LORA_ENABLE_PIN is optional and is driven before radio bring-up; the Elecrow 2.4/2.8 wireless module uses GPIO45 active-low.
  • Frequency and region are runtime (lora set region), not Kconfig.
  • Verify with lora status and lora diag after flashing. See Supported Hardware for board matrix.

For wiring help, see Development: Custom Board Configs.