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How the Flipper Zero uses the STM32WB55RG for specific tasks?

#flipperzero #stm32wb55rg #stm32wb #microcontroller

The Flipper Zero leverages the STM32WB55RG microcontroller in clever ways to enable its multifunctional hacking capabilities. Here’s how it handles key tasks:

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1. RFID/NFC Emulation & Scanning
Hardware Used:

  • STM32WB55RG’s SPI/I2C interfaces connect to the PN532 NFC chip (for 13.56MHz RFID/NFC).
  • GPIOs control the 125kHz RFID low-frequency (LF) circuit (EM4100, HID Prox).

How It Works:

  • The Cortex-M4 core processes RFID/NFC data.
  • Hardware AES acceleration decrypts/clones encrypted tags (MIFARE Classic).
  • Sub-1GHz radio (via STM32WB’s RF module) simulates HID/Flipper’s "Fuzzer" attacks.

2. Infrared (IR) Remote Control
Hardware Used:

IR transmitter LED & receiver (controlled via GPIO/TIM modules).

How It Works:

  • M4 core decodes/encodes IR signals (NEC, RC5 protocols).
  • Preloaded database of remote codes (TVs, ACs).
  • Can learn and replay signals like a universal remote.

3. BadUSB (HID Attacks)
Hardware Used:

USB 2.0 peripheral (in STM32WB55RG) emulates keyboards/mice.

How It Works:

Runs Ducky Script (converts scripts to keystrokes).

Example Attack:

bash
DELAY 1000
GUI r
STRING cmd
ENTER
Enter fullscreen mode Exit fullscreen mode

(Opens Command Prompt on Windows.)

4. Sub-1GHz Wireless (433MHz, 868MHz, etc.)
Hardware Used:

STM32WB’s built-in 2.4GHz radio + CC1101 chip (via SPI for Sub-1GHz).

How It Works:

  • Sniffs/clones garage doors, key fobs (e.g., Tesla Model 3 replay attacks).
  • "Fuzzer" mode bruteforces rolling codes (limited by crypto).

5. GPIO Hacking (Hardware Interaction)
Hardware Used:

Breakout GPIO pins (UART, I2C, SPI, 1-Wire).

Example Uses:

  • Read/write EEPROMs (via I2C).
  • Debug embedded devices (UART console access).
  • Control relays/sensors (DIY smart home exploits).

6. Bluetooth (BLE) Spoofing
Hardware Used:

STM32WB’s Cortex-M0+ core handles BLE stack.

How It Works:

  • Advertises fake iBeacons or Bluetooth keyboards.
  • Can intercept BLE traffic (limited without external sniffer).

Limitations of the STM32WB55RG in Flipper Zero

  • No 5GHz Wi-Fi (requires external ESP32 for Wi-Fi attacks).
  • Limited RAM (256KB) restricts complex payloads.
  • Sub-1GHz depends on CC1101 (not all frequencies supported).

Firmware Hacking Potential
FreeRTOS-based → Custom apps can be added (e.g., Wi-Fi Deauth with ESP32).

Community Plugins:

  • NMEA GPS parser (for geolocation attacks).
  • RFID brute-forcer (for weak crypto tags).

Want to Go Deeper?

  • Try writing a custom plugin (Flipper SDK uses C).
  • Add external hardware (e.g., ESP32-C3 for Wi-Fi).
  • Explore Flipper’s Sub-1GHz capture files (/subghz/ directory).

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