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Pocket-sized oscilloscopes decode CAN data

The Picoscope 2200A series oscilloscopes by Pico (UK) occupy about the area of a passport and are 19 mm thick. Connected to and powered by USB, they offer bandwidths up to 200 MHz and feature an arbitrary waveform generator.

The oscilloscopes are almost 80 % smaller than the previous generation of the series (Photo: Pico)

WITH THE PICOSCOPE 6 SOFTWARE, features such as serial decoding and mask limit testing are included. The USB connection enables printing, copying, saving, and emailing data from the field. The high-speed USB interface allows fast data transfer, while USB powering removes the need to carry around an external power supply.

Picoscope lets the user choose which channels they want to use for serial decoding and what serial protocol to use for each channel. Currently the oscilloscopes can decode CAN data, I²C, RS232/UART, SPI, I²S, Flexray, and LIN data. This list will grow over time with future software upgrades. Once the user has selected a protocol they can then change the adjustable settings. The adjustable settings vary depending on the protocol selected, but include settings such as bit-rate and threshold for CAN networks, and clock channel, clock threshold and data threshold for I²C.

The oscilloscopes are almost 80 % smaller than the previous generation of the series (Photo: Pico)

The decoded data can be displayed in the format of your choice: The “in view” format shows the decoded data beneath the waveform on a common time axis, with error frames marked in red. These frames can be zoomed to investigate noise or distortion. The “in window” format shows a list of the decoded frames, including the data and all flags and identifiers. The user can set up filtering conditions to display only the frames you are interested in, search for frames with specified properties, or define a start pattern that the program will wait for before listing the data. It is also possible to create a spreadsheet to decode the hexadecimal data into user-defined text strings.
The oscilloscopes provide real-time sampling rates up to 1 GS/s, equivalent to a timing resolution of only 1 ns. For repetitive signals, equivalent-time sampling (ETS) mode can boost the maximum effective sampling rate up to an incredible 10 GS/s, allowing even finer resolution down to 100 ps. All scopes support configurable length pre-trigger and post-trigger capture.

All oscilloscopes have a built-in arbitrary waveform generator (AWG). Waveforms can be imported from the oscilloscope, external data files or created and modified using the built-in graphical AWG editor. A function generator is also included, with sine, square, triangle, DC level and many more standard waveforms. As well as level, offset and frequency controls, advanced options allow you to sweep over a range of frequencies. Combined with the spectrum peak hold option, this creates a tool for testing amplifier and filter responses.

The oscilloscopes are almost 80 % smaller than the previous generation of the series (Photo: Pico)

As well as the standard range of triggers found on most oscilloscopes, the series offers a selection of advanced triggers. These include pulse width, windowed and dropout triggers to help you find and capture your signal quickly. Most digital oscilloscopes still use analog trigger architecture based on comparators. This can cause time and amplitude errors that cannot always be calibrated out. The use of comparators often limits the trigger sensitivity at high bandwidths and can also create a long trigger re-arm delay. The company has used full digital triggering using the actual digitized data for 20 years. This reduces trigger errors and allows our oscilloscopes to trigger on the smallest signals, even at the full bandwidth. All triggering is digital, resulting in high threshold resolution with programmable hysteresis and optimal waveform stability.

On selected models, the reduced re-arm delay provided by digital triggering, together with segmented memory, allows the capture of events that happen in rapid sequence. At the fastest timebase, rapid triggering can capture a new waveform every 2 μs until the buffer is full. The mask limit testing function helps to detect waveforms that fail to meet your specifications.

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