I2C_sniffer.sniffer Class Reference

Public Member Functions
def	__init__ (self, pi, SCL, SDA, set_as_inputs=True)
def	cancel (self)

Public Attributes
	bit
	byte
	cbA
	cbB
	FALLING
	gSCL
	gSDA
	in_data
	oldSCL
	oldSDA
	pi
	RISING
	STEADY
	transact

Private Member Functions
def	_cb (self, gpio, level, tick)
def	_parse (self, SCL, SDA)

Detailed Description

A class to passively monitor activity on an I2C bus.  This should
work for an I2C bus running at 100kbps or less.  You are unlikely
to get any usable results for a bus running any faster.

Definition at line 7 of file I2C_sniffer.py.

Constructor & Destructor Documentation

def I2C_sniffer.sniffer.__init__	(		self,
			pi,
			SCL,
			SDA,
			set_as_inputs = True
	)

Instantiate with the Pi and the gpios for the I2C clock
and data lines.

If you are monitoring one of the Raspberry Pi buses you
must set set_as_inputs to False so that they remain in
I2C mode.

The pigpio daemon should have been started with a higher
than default sample rate.

For an I2C bus rate of 100Kbps sudo pigpiod -s 2 should work.

A message is printed for each I2C transaction formatted with
"[" for the START
"XX" two hex characters for each data byte
"+" if the data is ACKd, "-" if the data is NACKd
"]" for the STOP

E.g. Reading the X, Y, Z values from an ADXL345 gives:

[A6+32+]
[A7+01+FF+F2+FF+06+00-]

Definition at line 14 of file I2C_sniffer.py.

Member Function Documentation

def I2C_sniffer.sniffer._cb (   self,   gpio,   level,   tick  )

private

Check which line has altered state (ignoring watchdogs) and
call the parser with the new state.

Definition at line 119 of file I2C_sniffer.py.

def I2C_sniffer.sniffer._parse (   self,   SCL,   SDA  )

private

Accumulate all the data between START and STOP conditions
into a string and output when STOP is detected.

Definition at line 63 of file I2C_sniffer.py.

def I2C_sniffer.sniffer.cancel

(

self

)

Cancel the I2C callbacks.

Definition at line 141 of file I2C_sniffer.py.

Member Data Documentation

I2C_sniffer.sniffer.bit

Definition at line 50 of file I2C_sniffer.py.

I2C_sniffer.sniffer.byte

Definition at line 49 of file I2C_sniffer.py.

I2C_sniffer.sniffer.cbA

Definition at line 60 of file I2C_sniffer.py.

I2C_sniffer.sniffer.cbB

Definition at line 61 of file I2C_sniffer.py.

I2C_sniffer.sniffer.FALLING

Definition at line 44 of file I2C_sniffer.py.

I2C_sniffer.sniffer.gSCL

Definition at line 41 of file I2C_sniffer.py.

I2C_sniffer.sniffer.gSDA

Definition at line 42 of file I2C_sniffer.py.

I2C_sniffer.sniffer.in_data

Definition at line 48 of file I2C_sniffer.py.

I2C_sniffer.sniffer.oldSCL

Definition at line 51 of file I2C_sniffer.py.

I2C_sniffer.sniffer.oldSDA

Definition at line 52 of file I2C_sniffer.py.

I2C_sniffer.sniffer.pi

Definition at line 40 of file I2C_sniffer.py.

I2C_sniffer.sniffer.RISING

Definition at line 45 of file I2C_sniffer.py.

I2C_sniffer.sniffer.STEADY

Definition at line 46 of file I2C_sniffer.py.

I2C_sniffer.sniffer.transact

Definition at line 54 of file I2C_sniffer.py.

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The documentation for this class was generated from the following file:

• I2C_sniffer.py