The figure displays I2C
interface analysis window, beneath it there is an image with work
screen area containing the timing charts for the clock channels (SCL)
and data channels (SDA). Marker 1 is set to start signal and marker 2
is set to start data byte transmission 0xFF.
The upper part of I2C windows contains an image of typical timing chart of I2C interface address and one byte transmission. Beneath it there is the panel of the main settings incident to the analyzed interface. Before you start decoding it is recommended to set the names of the interface channels on the panel "Channels" of logical analyzer. If you set the names SCL and SDA then they automatically appear in the fields of clock channel and data channel.
As is known from I2C interface specification, the data transmission session starts with the start signal transmission (when SDA goes from high level to low level while SCL is in high level) then address or data bits are transmitted, at that the high-order bits go first and then confirmation bit is transmitted. Stop signal completes the data transmission (when SDA goes from low level to high level while SCL is in high level). If there is not data communication in the bus then the logical level of SCL and SDA lines will be always high for the raising resistors. That's why it is expedient to turn on triggering as to the falling edge for the channel SDA. Before you start measuring it may be well to turn off the analyzed device and then press the Start button and turn on the device. If triggering is set correctly then the start of timing charts has to concur with start of communication. For the normal timing charts decoding it is necessary that the sampling frequency is 4 times higher than the triggering frequency.
Upon taking the timing charts it is desirable to set the marker 1 to start signal otherwise the nearest start signal right to the marker 1 will be searched and then one session may be skipped.
Upon completing all such procedures you can start decoding when pressing the Decode button. Decoding results will be displayed in the table in character format (start, stop, communication direction signal and confirmation signal) and in binary format (address and data). When double clicking on the selected cell with the decoding results the marker 1 goes to start of the corresponding I2C interface element.
It is necessary to note that in addition to the timing charts decoding I2C window also allows generating the timing charts on the basis of interface settings and table data (columns, address, R/W, data) for the channels SCL and SDA, which are to be one of the logical generator channels.
It makes sense to use the flag Auto (table field autofill) only if signal generation is required.
Button with microcircuit icon opens the terminal window - hardware support (input/output) of the analyzed interface.