Wiring Modules and Peripherals

What this does

This page explains how GhostESP maps add-on modules to ESP32 pins, and how to find the exact pins your board is already using.

Do I need this page?

If you bought or already own a supported board, you probably don’t. Every release build ships with its pins already configured, so a board with a built-in CC1101, NRF24, NFC, or GPS works out of the box.

You need this page when you are:

• Adding a module to a generic ESP32 board
• Changing SD card pins
• Building a custom board configuration

Before you start

• 3.3 V logic only. ESP32 GPIOs are not 5 V tolerant. Feeding 5 V into a pin can destroy the chip.
• Check the Supported Hardware table first — many “missing feature” problems are really “this board doesn’t have that hardware.”
• Have a way to read serial output at 115200 baud. Boot logs and status commands are how you confirm wiring.

Find your board’s pins

SD card (changeable at runtime)

sd_config

prints the pins currently in use. To change them without rebuilding:

sd_pins_spi <cs> <clk> <miso> <mosi>
sd_save_config

sd_save_config stores the pins in NVS so they survive a reboot. This is the only peripheral most users ever need to reconfigure by hand.

CC1101 SubGHz

Start the scanner and read the first log line:

subghz start

GhostESP prints the pins it is actually using:

SubGHz cfg: SPI2 MOSI=18 MISO=38 SCK=40 CSN=39 GDO0=41 GDO2=-1

If that line does not appear, the build was compiled without SubGHz support for your board.

Build-time pins

If you are compiling your own build, every peripheral pin is set under Ghost ESP Options in menuconfig:

The Kconfig defaults for a CC1101 are MOSI 18, MISO 38, SCK 40, CSN 39, GDO0 41, and GDO2 disabled (-1). These are generic defaults, not a wiring recommendation for any specific board — confirm against your board’s own configuration before connecting anything.

Module wiring reference

These are the signals each module needs. Match them to the pin numbers from the section above.

CC1101 (SubGHz)

Attach a frequency-matched antenna before transmitting. Powering a CC1101 without an antenna can damage the module’s output stage.

NRF24L01+

Note: the PA+LNA versions of the NRF24 draw far more current than the plain modules. A weak 3.3 V supply causes “radio not responding” failures that look like wiring bugs — add a decoupling capacitor across VCC/GND, or power it from a dedicated 3.3 V regulator.

PN532 (NFC)

Most PN532 modules support I2C, SPI, and UART, and the onboard DIP switches select the mode. GhostESP uses I2C for PN532:

Set the module’s switches to I2C before wiring. A PN532 left in SPI or UART mode will not respond.

GPS

GPS modules are UART devices. Cross the lines:

Most modules default to 9600 baud. Some need a battery or a clear view of the sky before they output a fix — no data indoors is normal.

Verified board wiring

These pinouts are documented elsewhere in the docs and are safe to follow directly.

Flipper Zero to ESP32

See the Flipper app connection guide for the full setup.

GhostLink (two GhostESP boards)

See GhostLink for pairing and transport setup.

GhostLink P1

The GhostLink P1 handheld has a complete, board-specific wiring map for its display, joystick, SD card, and charging circuit in its owner’s guide.

Troubleshooting

• Module not detected: confirm 3.3 V power first, then check that MOSI and MISO are not swapped. Swapped data lines are the most common SPI wiring mistake.
• One module works, another does not: modules on a shared SPI bus must each have their own chip-select pin, and only one may be active at a time. Boards that share a bus (the TEmbed C1101 is one) hold unused CS pins high to avoid conflicts.
• Works until you start a Wi-Fi or BLE task: radios compete for power and pins. See Control methods for what can run at the same time.
• Pins keep resetting after reboot: you changed them at runtime but did not run sd_save_config, or the build config overrides them.

Related tasks

• Supported Hardware
• SD card storage
• Custom board configurations
• Command line reference