Capture
How Capture Works
When you start a capture, the application opens a continuous USB bulk data stream from the hardware and writes it to a rolling disk file in the configured working directory. A background processing thread reads that file, decodes all protocol data in real time, and feeds the waveform display.
Capture data is stored on disk, not in RAM. This means captures can be dramatically larger than available memory — the application pages data between disk and memory as you navigate. You can capture for hours without running out of space as long as the file size limit is not exceeded (the file wraps to a ring buffer when full).
The Active-Pro™ Software runs and displays the captured data from your embedded system. The software comes up in the following state, ready to capture and visualize your data:
Quick Setup Configuration
The ACTIVE-Pro can capture all of the input channels simultaneously. With an Active-Pro plugged in, it can capture 8 channels of digital and 3 channels of analog at the same time.
Although you can individually show each signal, there are a number of Quick Configurations that let you instantly select just the channels you need. Click Setup on the menu and select the Quick Setup configuration of your choice:
Selecting Channels to Capture
Select the top tab on the right-hand side of the screen to show the Input Channel Setup window:
Analog Input Channels
To enable or disable capturing of an analog channel, click the CH1, CH2, CH3, or CH3/CH4 button. Select the analog input range using the drop-down box to choose −10V to +10V, or 0V to 20V ranges. Select the analog sample rate using the drop-down box from 10 sps to 1 Msps.
Digital Input Channels
To enable or disable capturing of a digital channel, click the 0, 1, 2, 3, 4, 5, 6, or 7 button. These buttons determine if that channel will be captured and a waveform of the signal will be displayed.
ACTIVE Digital Logic Threshold
The ACTIVE-Pro features variable Digital Logic Thresholds that can range from 0V to +4V. Set the logic threshold to the logic family you are using. This will set the voltage level that indicates the change from a logic "0" to a logic "1".
If this level is set incorrectly, or too close to either the top or bottom of your logic range, you will see inconsistent waveforms and this level will need to be adjusted.
Hardware Bus Decoders
There can be up to 4 hardware bus decoders that operate on the associated signals. These bus decoders are active even if the digital input signal is not captured. Select the type of bus by clicking the drop-down list.
Available Device Capture Types for each device A, B, C and D are:
- ACTIVE-PRO Debug Bus
- EE101 Debug Bus
- I2C, SPI, UART, RS232, 1-Wire, MDIO, LIN, DS101, and CHSI
Helpful Hint: To maximize the performance of the capture, make sure that any channels that are not necessary for a trace are turned off.
UART modes, ACTIVE 1-Wire and EE101 1-wire buses have an Auto Baud feature. When you press the Auto-Baud button, the Active-Pro measures the digital inputs for 1 second and computes the baud rate of the signals for that device at that time. It then sets the baud rate setting to the value calculated.
Starting a Capture
Press Space or click the CAPTURE button in the status bar.
The button label immediately changes to STOP CAPTURE. The waveform display begins updating in real time as data arrives and is decoded. The total number of captured bytes is displayed at the bottom during capture.
Only signals and channels that are active are shown on the display automatically — if your firmware only outputs data on one channel, only that channel appears.
During a live capture, you can scroll backward in the waveform to review earlier data. The DISPLAY LIVE DATA button in the status bar becomes active; click it to jump back to the end and resume auto-scroll.
Stopping a Capture
Press Space or click STOP CAPTURE in the status bar.
The capture ends and the waveform is now fully navigable. All data from the beginning to the end of the capture is available.
Pressing Capture again will erase the previous capture and start a new one.
Starting a New Capture
File > New Capture clears all current capture data and resets the waveform display to empty.
All settings are preserved: channel names, decoder modes, colors, PacketPresenter definitions, and notes all remain. Only the captured waveform data is cleared.
Capture File Settings
These settings are in the Settings tab on the right-side panel.
Working Directory
The folder where the capture data file is written during capture. Click the ... button to browse for a different folder.
Tip: Set the working directory to a fast local drive. For very large captures (hundreds of GB), use an SSD.
Max Capture File Size
Sets the maximum size the capture data file can grow to on disk. Options:
1 MB · 10 MB · 100 MB · 1 GB · 10 GB · 100 GB · 1 TB
When the file reaches this size, the oldest data is overwritten (ring buffer). New data continues to be recorded.
Tip: For debugging intermittent problems, set a large capture size and let the tool run. When the bug appears, stop the capture — the data surrounding the event is preserved.
Max Analog and Digital Sample Rate
Sets the upper limit on the analog and digital sample rate. Options:
20 · 50 · 100 · 200 · 500 · 1K · 2K · 5K · 10K · 20K · 50K · 100K · 200K · 500K · 1M (samples per second)
Reducing the sample rate reduces capture file growth rate, extending how long you can capture before the ring buffer wraps.
Saving a Capture
Save Entire Capture
File > Save Capture saves the entire current capture to a .active file. A save dialog appears if this capture has not been saved before. Saving large buffer sizes can take a while; a percentage complete is displayed at the bottom of the application.
The .active file stores everything needed to restore the session exactly:
- All captured waveform data (logic, analog, Active Debug Port, PacketPresenter output)
- Channel names, colors, and visibility settings
- Decoder mode for each device port
- PacketPresenter definitions
- Analog calibration settings (ACTIVE-PRO and ACTIVE-PRO Ultra)
- Notes (rich text)
- Analysis Context text
Save Between Cursors
File > Save Between Cursors saves only the data within the X1-to-X2 cursor range to a new .active file. This is useful for extracting a specific event from a long capture and saving it as a smaller, focused file to share with a colleague or attach to a bug report.
Opening a Capture
File > Open Capture (Ctrl+O) opens a .active file. The application restores all waveform data, settings, channel names, and notes from the file. Opening files with large buffer sizes can take a while to decompress and display.
Recent Files
File > Recent Files lists the last 5 .active files you have opened or saved. Click any entry to open it immediately.
Configuration Files
Available on: ACTIVE-PRO · ACTIVE-PRO Ultra (not available on Active Debugger)
A configuration file saves your settings — decoder modes, channel names, PacketPresenter definitions — without saving any capture data. Configuration files are useful for sharing a channel setup with a colleague or quickly reconfiguring the tool for a different project.
File > Save Configuration saves all current settings to a .ini file.
File > Open Configuration loads settings from a configuration file and applies them to the current session. Captured waveform data is not affected.
A configuration file includes: channel names, decoder modes, baud rate and decoder settings, analog offset/scale/units per channel, PacketPresenter definitions, and channel visibility settings.