Embedded designs consist of multiple serial protocols and components that
require deeper analysis. Learn how to fully characterize your embedded or
mixed-signal designs to find any errors that could disrupt your device's performance.
Hi I'm Erin east with Keysight and in this video you'll learn
how to test and debug your embedded designs. This includes protocol
triggering and decoding for I squared C, SPI, UART/RS-232, I squared S, and USB PD,
also known as USB power delivery. The primary reason you should use an
oscilloscope to debug and characterize embedded serial buses is because of an
oscilloscope's inherent ability to characterize the analog quality of the
signal. It also allows you to time correlate serial activity with other
analog and digital i/o signals in your design.
Today's embedded designs based on microcontrollers and digital signal
processors often include a combination of real-world analog signals, digital i/o
buses, and serial buses. Although microcontrollers and DSPs are
often thought of as simply digital control and processing devices, most MCUs
and DSPs today are mixed signal devices. I squared C, SPI and
UART/ RS-232 are often used for chip-to-chip communication between MCUs and memory
chips as well as other peripherals. There are many helpful capabilities in
the Infiniivision oscilloscopes that allow you to debug easier and faster
like the hardware based serial decoding for responsiveness, the dual bus time
interleave protocol lister display, digital channels from mixed signal
analysis, the ability to capture a long time span of packets in detail with
segmented memory, and a real time frame error counter. You can test all buses in
your embedded design and mixed signal designs with the Infiniivision embedded
software package. This also allows you to perform pass/fail mask testing, frequency
response analysis, and enhance HDTV video triggering. I
mentioned the hardware-based decoding. this is contrary to the
software decoding that you'll find in other oscilloscopes from other vendors.
Because there's a dedicated hardware component for the serial decoding, you're
basically decoding in real time. There's no lag and responsiveness like what you
would see with software decoding from other vendors. Hardware decoding is
significantly faster and this means that you're more likely to capture rare
errors and random glitches. So let's take a look at the scope and how to set up
serial decoding. This setup process is generally the same for every type of
serial bus. To start out of course you have to probe on your device. Right now
I'm probing on an I squared C bus and it's clock, but we see there's no
decoding on-screen and we don't have a stable trigger. First and foremost you
have to tell the oscilloscope you want to perform serial decoding. Cnce you have
serial turned on, set the mode to whichever bus type you're decoding.
Notice in the decoding bar the data is in various colors and formats.
If you hold down the mode button you can see the meanings of each of those
symbols, hex values, or colors. Next define the signal that you're trying to decode.
In this case I mentioned we're working with a serial clock and the I squared C
data. To enable the I squared C trigger and decoding along with other embedded
buses and analysis options you can download the free trial of the embedded
software package from the website linked on screen or in the description. So now
that we're all set up to decode that serial bus we have to set a stable
trigger. To trigger on various events within the bus, turn on the serial
trigger and choose what to trigger on. Depending on the trigger you select
specify the address or the data that you wish to analyze further and note that
you can actually use the zone triggering capability to isolate various parts of
the serial bus as well. So now we have a very stable trigger and can analyze the
data in each packet. The lister allows you to navigate through each packet or
strings of packets with details on timing, the address, and the data. If you
have to further analyze specific trigger events or packets the standard segmented
memory capability can be used to capture up to
a thousand events. This can be done with any serial mode including those on the
digital MSO channels. So let's look at this 4-wire SPI decode with the
trigger set on the MOSI and MISO data. Using segmented memory we've captured
600 trigger events. By scrolling through each event in the Lister or sidebar you
can see the MOSI and MISO data. Each click on the different Lister row or
timestamp will show that specific section of the data on-screen including
the decode information. To learn more about what segmented memory is and how
to set it up check out my What is Oscilloscope
Segmented Memory video on our Keysight Labs YouTube channel. Also remember that
you can probe your mixed signal designs as well and view both the digital and
analog signals at the same time. Doing so turns your oscilloscope into an MSO: a
mixed signal oscilloscope. An MSO is a hybrid test instrument that combines the
measurement capabilities of a digital storage oscilloscope, a DSO, with the
important aspects of a logic analyzer or serial protocol bus analyzer. This means
that you can view up to 4 analog signals and 16 digital signals simultaneously.
And this is all being done in hardware, so the update rate remains uncompromised.
You'll continue to see an incredibly fast response of up to a million
waveforms per second. On most other oscilloscopes with software decoding
turning on these digital channels will cause your update rate to drop
significantly causing you to miss important signal events. And lastly you
can also simultaneously analyze two types of serial buses using the dual bus
time interleaved decoding. To initiate this you simply turn on two serial bus
types when you're setting up the serial options. Set up each bus to the specified
mode and set your trigger. With this you can see if a bus is triggering the
appropriate events in another bus or you can view the timing of events between
two buses. I also mentioned that the embedded software package enables a few
advanced analysis capabilities as well such as mask testing,
frequency response analysis, and HDTV video triggering. If you need to
validate the quality and stability of your components or systems the mask
testing capability can save you time and provide pass/fail statistics almost
instantly. Mask testing offers a fast and easy way to test your signal to
specified standards as well as the ability to uncover unexpected signal
anomalies such as glitches. Mask testing on other oscilloscopes is usually based
on software intensive processing technology which tends to be slow. Much
like the software decoding that you learned about. With mask testing being
performed in hardware on the Infiniivision oscilloscopes you can test
up to two hundred and seventy thousand real-time waveform pass/fail tests per
second. This makes your testing throughput orders of magnitude faster
than what you could achieve on other oscilloscopes software mask testing. The
creation of the mask is simple with the auto mask function or the option to
upload custom masks. You can also download multi-region masks and setup
based on your industry standards from our website. Frequency response analysis
or FRA is often a critical measurement used to characterize the frequency
response of a variety of today's electronic designs including passive
filters, amplifier circuits, and negative feedback networks in switch mode power
supplies or the loop response. The frequency domain measurement capability
is achieved with a swept gain and phase measurement versus frequency. This is
also known as a bode plot. The Infiniivision oscilloscope uses the scope's built-in
waveform generator to simulate the circuit under test at various frequency
settings and then it captures the input and output signals using two channels of
the oscilloscope. At each test frequency the scope measures, computes, and plots
the gain logarithmically and the phase linearly. And lastly whether you're
debugging consumer electronics with HDTV or characterizing a design the enhanced
HDTV video triggering and analysis provides support for a variety of HDTV
standards. This enhanced video measurement
capability supports a video IRE display grid with cursor measurements performed
in the video IRE units for NTSC and PAL standards. In addition enhanced video
analysis provides an array of additional HDTV triggering standards that will help
you speed up debug and characterization. You can see how the plethora of embedded
decodes and analysis capabilities enable you to fully characterize your embedded
and mixed signal designs. Using functions like the segmented memory, the MSO
options, and dual bus time interleaved decoding you're able to analyze various
events simultaneously. Furthermore you can analyze the other components of your
embedded design such as the switch mode power supply or any filters with the
Keysight infiniivision exclusive frequency response analysis capability.
The unmatched hardware-based mask testing and segmented memory
capabilities allow you to dive even deeper into the analysis. Download a free
trial of the Infiniivision embedded software package that goes with your
oscilloscope and learn more about it by checking out the link on screen or in
the description. As always place any questions in the comments section below
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