I²C analyzer
The I²C analyzer sink decodes analog data on an I²C bus to I²C data.
Just measure the Clock and Data lines of the I²C bus with a scope and connect
the measuring channels to an analyzer sink.
The I²C analyzer always needs two sources: the first connected source will be used as I²C SCL (clock) and the second connected source will be used as I²C SDA (data).
The sink uses a window for its output. The output can be saved to a text file.
Usage
Acquisition settings
For best results, use the following setups to capture the data:
| I²C mode | Minimum sample frequency | Pre-trigger | Trigger timeout | Trigger channel | Trigger type | Trigger level |
|---|---|---|---|---|---|---|
| Standard | 500 kHz | 1% | Infinite | I²C SDA (data) | Falling | 2 V |
| Fast | 2 MHz | 1% | Infinite | I²C SDA (data) | Falling | 2 V |
Note: Currently I²C High Speed mode is not supported.
Address aliases
I²C uses device addresses to communicate to specific devices on the bus. For easy recognition of the devices in the decoded data, the I²C analyzer supports address aliases. Address aliases can be added and changed on the Aliases page of the output window.
On the aliases page in the output window, the following actions are available:
Add address
Add an address item to the list of address aliases.
Edit address alias
Edit the address alias of the selected item in the list of address aliases. This can also be achieved by double clicking the address field on the selected line.
Remove selected address
Remove the selected address item from the list of address aliases.
Load I²C address file
Load a file with address aliases.
Save I²C address file
Save the current list of address aliases to a file.
Properties and actions
To control the behavior of the I²C analyzer sink, several properties and actions are available. These can be accessed through a toolbar with buttons at the top of the I²C analyzer output window and through a popup menu which is shown when the sink is right clicked in the Object tree.
Voltage
I²C supports two different bus voltages: 3.3 and 5 V. The Voltage property needs to be set accordingly for proper decoding. The default value is 3.3 V. The Voltage property is available through the popup menu.
Clear
The Clear action clears all text from the I²C analyzer output window The Clear action is available as button on the toolbar.
Swap inputs
The I²C analyzer always needs two sources: the first connected source will be used as I²C SCL (clock) and the second connected source will be used as I²C SDA (data). When the sources are connected the wrong way, the Swap inputs action will correct it. The Swap inputs action is available as button on the toolbar and through the popup menu.
Auto scroll to bottom
The Auto scroll to bottom property makes the I²C analyzer output window scroll to the bottom of its content each time new data has arrived, making the latest data visible. The Auto scroll to bottom property is available as button on the toolbar.
Export data
The Export data action saves the content of the I²C analyzer output window to a text file. The Export data action is available as button on the toolbar.
Always on top
When the Always on top property is switched on, the I²C analyzer output window cannot be hidden under other windows of the Multi Channel software. The Always on top property is available in the popup menu.
Common properties and actions
Alias
You can change the displayed name of an object by giving it an Alias. This can be handy when you are dealing with a lot of objects and have problems keeping them apart. You can for example give channel one of your instrument the alias "Battery", when it is measuring a battery voltage. To give an object an alias, use the item Alias ... in its menu. To remove an alias and revert to the original name of the object, set the alias to an empty string.
Disconnect source(s)
To disconnect one or more sources from an I/O or Sink, use the Disconnect source(s) action. This will show a dialog that lists all connected sources. Individual sources can then be selected and disconnected from the object.
Disconnect all sources
To disconnect all sources from an I/O or Sink at once, use the Disconnect all sources action.
Clone
When a new object is to be created, similar to an already existing object, with the same properties, the Clone action can be used. This will create an identical copy of the original object, with the exact same properties. Source(s) and sink(s) of the new object are not yet connected.
Delete
The Delete action deletes a source, I/O or sink. All connections of the object will be disconnected and then the object will be removed from the object tree. The source property of the objects that used this object as source will be cleared. The sink property of the objects that used this object as sink will be cleared. An axis in a graph that was connected to this object will be also deleted.
Load
The Load action allows to load the settings and data for an object from a TPS or TPO file. This is detailed described on the page about Loading into selected objects.
Save as
The Save as action allows to save the settings and data of one or more objects to a TPO file. When multiple objects are selected, the connections between the objects are saved as well. This is detailed described on the page about Saving objects to a TPO file.