sniff command in 2WIRE mode logs I2C-like protocols that don’t have an ACK/NAK bit. This includes SLE4442 IC cards and TM1640 LED drivers, among others.
Now you can sniff the unlock code for SLE4442 cards and steal photo copies and laundry service in a late 90s university dorm! (I make this joke hoping none of these system are still in use 30 years later… stealing is bad m’kay)
I2C format
| Start Bit | Data Bits (8) | ACK/NAK | Stop Bit |
|---|---|---|---|
| [ | 0xA5 | +/- | ] |
- Start Bit ([): Indicates the beginning of an I2C transaction.
- Data Bits (8): The 8-bit data being transmitted (e.g., 0xA5, 0x3C).
- ACK/NAK (+/-): Acknowledgment (ACK) or Not Acknowledgment (NAK) from the receiver.
–+ for ACK
– - for NAK - Stop Bit (]): Indicates the end of an I2C transaction.
2WIRE format
| Start Bit | Data Bits (8) | Stop Bit |
|---|---|---|
| [ | 0xA5 | ] |
- Start Bit ([): Indicates the beginning of an 2WIRE transaction.
- Data Bits (8): The 8-bit data being transmitted (e.g., 0xA5, 0x3C).
- Stop Bit (]): Indicates the end of an 2WIRE transaction.
The only difference is the missing ACK/NAK bit.