Acquiring data from a digital bus
Once you have connected your ChronoVu probe to the Device Under Test, and filled in the appropriate fields in the Data Acquisition Setup menu, you are ready to acquire the data from your bus.
Be sure that your Device Under Test (DUT) is powered and running, then start monitoring the DUT signals by clicking on the icon on the tool bar, or the Data Acquisition–>Acquire Data menu item from the menu bar. (see User Interface for assistance). The ChronoVu logic probe will immediately begin watching the bus, awaiting the specified trigger condition. The red “idle” light on the ChronoVu probe will be replaced by a yellow “acquire” light. Once the trigger condition has been observed, the green “triggered” light will also be lit. Data acquisition will automatically terminate once the 8Msample data buffer has been filled, at which time the yellow “acquire” light will be replaced by a yellow “download” light, and the data will be downloaded through the USB port, and displayed in the Signal Display Window. After data download has been completed, the red “idle” light will again be lit. Should the trigger condition not be observed within the specified trigger timeout period (which can be specified on the Data Acquisition Setup menu), the ChronoVu probe will automatically reset, and no data will be collected. Should this occur, simply adjust your trigger conditions, and try again.
Examine the results
Once the data acquisition sequence has completed, the acquired data will be immediately displayed on your screen. The time scale has been set such that the trigger condition occurs at time zero. Unless the trigger condition occurred as soon as the ChronoVu probe was enabled, (as will be the case if all signals were specified to trigger on “Any state”), the data window will contain a small amount of pre-trigger data, as indicated by negative values on the time axis. You can now zoom or pan to adjust the view in the signal display window. The exact time at which an edge or event occurred can be obtained by placing a marker at the desired point. An “L” or “R” marker can be placed or moved by clicking the left or right mouse button at the desired point in the signal display window, and removed by double clicking the same mouse button. Signal names, colors, visibility, etc. can be modified from the Data Acquisition Setup menu to modify the visual appearance. Such changes will modify the current view, but will have no effect on the acquired data. (Note, in particular, that changes to the “sample rate” field on the Acquisition Setup menu will have no impact on data that has already been acquired).
Once data has been acquired and displayed, it can be saved to a file on your hard disk. Once saved, the data can be reloaded from a file at any time for further viewing, analysis, printing, etc. Only the actual data is stored in the data file. Signal names, colors, visibility settings, bus analysis settings, etc are not saved in the data file, but can be saved, if desired, in a separate “setup file”. The setup file will be discussed in more detail later in this tutorial. (See Saving and Loading Files for additional details.)