BLE (Bluetooth low energy) jammer using nRF24L01+ modules and a simple STM32 microtroller like the Maple Mini/ Bluepill

BLE uses 40 channels, 3 of which are used for advertising and the other 37 are used for data transmission. Data transmission on the other 37 channels are usually done with adaptive frequency hopping to minimize interference.

On the other hand, BLE discovery is made possible by 3 advertising channels (2402MHz, 2426MHz and 2480MHz). These 3 advertising channels transmit the characteristics and Mac Address of the device. On newer BLE devices, advertising uses all 3 channels, hence the need to generate noise on all 3 channels in order to achieve maximum effectiveness in jamming BLE discoverability.

This is far more feasible than jamming all 40 channels with a wideband jammer as it risks affecting other network such as WiFi.

Based on the above spectrogram, we can see that all 3 channels (2402MHz, 2426MHz and 2480MHz) are clearly flooded (blue is silence, green and other colors represent a signal). This would prevent BLE scanners from reading other BLE advertising transmissions.

To reproduce the above outcome, we will use 3 nRF24L01+ modules and transmit a single character "x" repeatedly using writeFast. This ensures that the module transmits without auto-acknowledgement and auto-retry which are features of the chipset turned on.

radio2.setAutoAck(false); may not be needed with writeFast.

We also set the module's data rate to 2Mbps so that it will utilize a wider band (2Mhz) instead of (1Mhz) to cover a larger bandwidth for jamming.

radio2.setDataRate(RF24_2MBPS);

1. 1x Maple Mini (STM32) or Arduino
2. 3x nRF24L01+

The nRF24L01+ (by Nordic Semiconductor) is a highly integrated, ultra low power (ULP) 2Mbps RF transceiver for the 2.4GHz ISM (Industrial, Scientific and Medical) band.

• Power supply : 1.9~3.6V
• ~520m Range at 2Mbit Data Rate
• Auto Acknowledge
• Auto Re-Transmit
• Multiceiver - 6 Data Pipes
• 32 Byte separate TX and RX FIFOs
• Software selectable channel: 2400MHz to 2525MHz (125 Selectable channels)
• Minimum number of external components
• Pins broken out : VCC, CE, CSN, SCK, MOSI, MISO, IRQ, GND

nRF24L01+ is a narrowband tranceiver (~2MHz) but that works to our advantage as BLE is also narrowband by design (~2MHz).

Disclaimer: This project is for educational purposes only. How you use this information is your own responsibility. I will not be held accountable for any illegal activities.