NanoXplore NXscope user manualNote that in the current version, all settings including trigger conditions are purely static. Any modification requires a re-generation of the NXscope

© NanoXplore 2020

NXscope

Ver 1.1

April 2019

NXscope user ’s gu ide Ver s ion 1.1

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Table of Content TABLE OF CONTENT ................................................................................................................... 2

1 NANOXSCOPE OVERVIEW................................................................................................... 4

1.1 NXSCOPE FEATURES SUMMARY ........................................................................................... 5 1.2 GENERATING THE NXSCOPE IP CORE .................................................................................. 5 1.3 INSTANTIATE THE NXSCOPE IP CORE IN YOUR DESIGN AND LAUNCH THE IMPLEMENTATION ........ 6

1.3.1 Inputs : ...................................................................................................................... 6 1.3.2 Outputs ..................................................................................................................... 6 1.3.3 JTAG pins: ................................................................................................................ 7

1.4 IMPLEMENT THE DESIGN AND GENERATE THE BITSTREAM ........................................................ 7 1.5 LAUNCH NXBASE2/NXBOARD AND NXSCOPE COMMANDS ...................................................... 7

2 CREATING YOUR CUSTOMIZED NANOXSCOPE IP CORE ................................................. 8

2.1 ENTITY NAME : ................................................................................................................... 8 2.2 CAPTURE CONFIGURATION .................................................................................................. 9

2.2.1 Input line count : integer range 2 to 240 ..................................................................... 9 2.2.2 Capture_depth: integer range 2048 to 49152............................................................. 9 2.2.3 Capture_mode: “Pre-trigger” or “Multiple windows” .................................................... 9 2.2.4 Window capture length: integer range 64 to 2048 .................................................... 10 2.2.5 Pre-trigger_samples”: integer range 0 to capture_depth-1 ....................................... 10 2.2.6 User data delay: integer range 0 to 2 ....................................................................... 10 2.2.7 Store trigger pulse: Enable or Disable ..................................................................... 10 2.2.8 Store window number: Enable or Disable ................................................................ 10

2.3 TRIGGER CONFIGURATION ................................................................................................. 11 2.3.1 Trigger line count: integer range 1 to 32 .................................................................. 11 2.3.2 Trigger mode: “Basic” or “Basic & Edges” ................................................................ 11 2.3.3 Multiple level trigger: “Enable” or “Disable” .............................................................. 11 2.3.4 Trigger value: .......................................................................................................... 11 2.3.5 First level trigger value: ........................................................................................... 12

2.4 NXSCOPE IP CORE GENERATION : ..................................................................................... 12

3 NXSCOPE CAPTURE TOOLS ............................................................................................. 13

3.1 WITH NXBASE2 SOFTWARE: ............................................................................................... 13 3.2 USING NXBOARD GUI: ..................................................................................................... 13 3.3 NXSCOPE RESULTS FORMAT: ............................................................................................ 15 3.4 NXSCOPE CAPTURE SEQUENCE: ........................................................................................ 15

4 NXSCOPE CAPTURE AND DISPLAY EXAMPLE ................................................................ 16

4.1 LAUNCH NXBASE2/NXBOARD AND NXSCOPE COMMANDS .................................................... 16 4.2 DISPLAY AND ANALYSIS OF THE CAPTURED RESULTS ............................................................ 16

4.2.1 Open ModelSim and launch the testbench simulation .............................................. 16 4.2.2 Open the .VCD result file with GTKWave and view/analyze the captured results ..... 17

5 NXSCOPE IP CORE CONFIGURATION EXAMPLES .......................................................... 18

5.1 EXAMPLE 1 : 12K X (25 + 1) CAPTURE WITH 50 SAMPLES PRE-TRIGGER CONDITION ................. 19 5.2 EXAMPLE 2 : 24K X (33 + 1) CAPTURE (2 SAMPLES PRE-TRIG COND) ...................................... 20 5.3 EXAMPLE 3 : 8K X (42 + 1 + 4) CAPTURE (2 SAMPLES PRE-TRIG COND) .................................. 21

6 KNOWN ISSUES .................................................................................................................. 22

7 HOW TO ORDER A NXSCOPE LICENSE ............................................................................ 23


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1 NanoXscope overview

NXscope is an embedded logic analyzer. It allows to sample a collection of internal data synchronously with a user’s clock (rising edge sensitive) and analyze the sampled results in a waveform viewer. NXscope is a NanoXplore IP Core. It’s generated by using the NXcore generator. The capture process is controlled by JTAG via the ANGIE USB-JTAG adapter with commands supported by NXbase2 software or NXboard GUI. The results can be displayed and analyzed either with :

ModelSim wafeform viewer (using a simple testbench to read the .txt file generated by NXcore generator and display the waveforms).

GTKWave (free waveform display tool) Note that the NXscope logic analyzer is built with the FPGA available logic resources such as tile logic and RAM blocks. Its implementation must also meet the user’s clock period as well as other potential user’s constraints.

The NXscope IP Core is made of three main functional blocks :

- Trigger engine : parametrizable module. It’s in charge of detecting the trigger

condition to launch the samples capture

- Capture unit : This module stores the captured samples upon trigger condition(s)


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- JTAG interface : Allows to start the trigger engine and read the captured samples to

send them via ANGIE USB-JTAG adapter to the computer, using NXbase2 software or NXboard GUI.

1.1 NXscope features summary

• Trigger features :

• 1 to 32 trigger input lines • Optional trig immediate input • Single or dual sequential trigger conditions • Level based (basic) or level and edges (basic_and_edges) trigger

• Capture features

• Capture width 2 to 240 input lines • Capture depth 2K, 4K, 6K, 8K, 12K, 24K or 48K • Programmable number of samples stored before trigger condition • Optional capture by windows mode (the capture depth is divided in multiple

sub-windows) • Optionally stores the TRIG_PULSE • Optionally stores the Window number if it applies

NXscope trigger and capture conditions are flexible:

- Up to 32 trigger lines - Single or two-level trigger conditions - Basic trigger conditions on ‘0’, ‘1’ or ‘X’ on each one of the trigger lines - Edge detection (rising, falling or both) on up to 32 trigger lines - User’s defined pre-trigger storage (not available when two-level trigger is selected) - Trig on condition(s) - Trig immediate (no condition) - Up to 240 sampled signals

Using NXscope is typically a four step process which consists in:

1.2 Generating the NXscope IP Core

The NXscope IP Core is generated by using the NXcore generator tool. It can then be instantiated in the user’s design

All trigger and data sampling parameters are defined by the user. This includes:

Number of data lines to be sampled (up to 240)

Sampling depth

Trigger conditions o Number of trigger lines: 1 to 32 o Single or dual trigger condition (a first condition must be met before

looking for the second and final trigger condition) o Trigger mode (“basic” or “basic_with_edges”) o Post or pre-trigger storage : The user can specify the number of

samples to be stored before the trigger condition has been met.

Note that in the current version, all settings including trigger conditions are purely static. Any modification requires a re-generation of the NXscope IP Core, and design implementation.


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Next generation versions will provide higher flexibility and more advanced features.

1.3 Instantiate the NXscope IP Core in your design and launch the implementation

After generating its customized NXscope IP Core, the user must instantiate it in its design, and launch the implementation and bitstream generation.

The signals to be connected are :

1.3.1 Inputs :

CLK : in std_logic; User’s clock

ENA : in std_logic; Enables the clock edges for all NXscope internal logic, including trigger and capture. Can be tied to ‘1’ if not required.

TRIG_LINES : in std_logic_vector User’s defined (1 to 32 bits)

DATA_LINES : in std_logic_vector User’s defined (2 to 240 bits)

TRIG_IMMEDIATE : in std_logic; Can be optionally used to resume a pending capture when the trigger condition can’t be met. Starts an immediate capture when going high.

1.3.2 Outputs

The outputs of NXscope IP Core can be used optionally as status information.

TRIG_ARMED : out std_logic; Can be optionally used to monitor the NXscope internal status

DONE : out std_logic; Goes high when the capture in internal memory is done. Can be optionally used as status bit. NXscope software starts reading the memory contents on a low to high transition on DONE signal.

FIRST_LEVEL_TRIG_OK : out

std_logic; Optional status bit to inform about the current state of the analyzer when two-level trigger is selected. Goes high after the first level trigger condition has been met. Can be directed for example to a LED.

CURRENT_CAPTURE_SET : out

std_logic_vector(3 downto 0); Optionally used as status bits. Available exclusively in “Multiple windows” mode.


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Can be used to monitor the progress of the capture windows.

Those 4 bits form a counter that is incremented by one each time a new window capture is started. Beyond 15 windows, the counter wraps around.

1.3.3 JTAG pins:

The captured samples are read by “nxbase2” or “nxboard” software, via ANGIE USB-JTAG adapter. Note that the JTAG pins are buried in the NXscope IP Core. No need for the user to directly refer to JTAG pins.

1.4 Implement the design and generate the bitstream

Check reports to ensure timing constraints are met.

1.5 Launch NxBase2/NXboard and NXscope commands

In order to sample the data lines, you must use the Angie USB-JTAG adapter, and the NXbase2 software or NXboard GUI.

See chapter 3 for basic instructions referring to NXbase2 and/or NXboard commands.

For more detailed information about the available commands please refer to the NXbase2 user’s manual.

Once the data has been captured an ACSII file is generated (.TXT or .VCD), and the results can be analyzed in the ModelSim waveform viewer (.TXT result file), with a simple testbench or with the free GTKwave waveform display software using the .VCD result file.


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2 Creating your customized NanoXscope IP Core

The NXscope generator is a GUI where you can define all available parameters of the logic analyzer.

In order to launch the NXscope generator, launch first the NXcore GUI (by typing the “nxcore” command at the prompt, and then, select the “NXscope” icon on the GUI left top side.

The next figure is a screen capture of the NXcore / NXscope generator GUI. All customizable parameters are available in this single page.

When all NXscope parameters are set, the IP Core can be generated by pressing the « generate » command, in the bottom-right part of the window.

2.1 Entity name :

The NXscope generator generates a VHDL encrypted file. The entity name is entered here. The VHDL path and file name are chosen with the “Generate” (bottom-right of the window). The entity can then be instantiated in the design as VHDL component.


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The generated VHDL file includes a header (not encrypted) where the user can see the ports names, modes, and width.

2.2 Capture configuration

2.2.1 Input line count : integer range 2 to 240

Up to 240 internal signals can be sampled and captured.

2.2.2 Capture_depth: integer range 2048 to 49152

Defines the capture depth of the DATA_LINES sampled and stored on internal RAM block(s). The maximum depth is 48K.

Allowed capture depth (samples number) :

- 2048 (2K)

- 4096 (4K)

- 6144 (6K)

- 8192 (8K)

- 12288 (12K)

- 24576 (24K)

- 49152 (48K)

Both “Capture_depth” and “Input line count” define the amount of internal RAM to be used by the IP Core, as for example:

- A single memory block can store up to 2048 x 24-bit words.

- With 10 RAM blocks up to 24K x 20-bit words can be stored.

2.2.3 Capture_mode: “Pre-trigger” or “Multiple windows”

This setting allows to assign one or more capture windows to the NXscope capture memory.

- “Pre-trigger”: the “Capture depth” is used as a single capture windows that uses the whole depth. In this mode the user can define the number of samples to be stored before reaching the trigger condition. For example, a 2048-word allows to store N samples before, and 2048-N samples after the trigger condition. Alternately, this mode supports a two-level trigger. In this case, a first trigger condition must be met, then the second (and final) trigger condition starts the data capture.

- “Multiple windows”: the “Capture depth” is divided in multiple sub-windows allowing multiple captures until filling the complete available RAM. As an


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example, if “Capture depth” = 2K, the user can define 4 windows of 512 samples. The setting of “Window capture length” defines the length of the sub-windows.

2.2.4 Window capture length: integer range 64 to 2048

This setting allows to define the length of the capture windows when “Capture mode” = “Multiple windows”.

2.2.5 Pre-trigger_samples”: integer range 0 to capture_depth-1

- When “Capture mode” is set to “Pre-trigger” and “Multiple level trigger” is “false” it’s possible to sample data before reaching the trigger condition. “Pre-trigger samples” defines the number of samples acquired before the trigger condition is met.

- If “Multiple level trigger” is set to true, the value of “Pre-trigger samples” is ignored, and the capture starts when the second trigger condition is met.

However, in any mode, the user has still the option to store up to 2 samples to be acquired before triggering, by using the “User data delay” setting.

2.2.6 User data delay: integer range 0 to 2

Available in all trigger modes, this setting allows to store 0 to 2 samples before meeting the trigger condition. It can be particularly useful in “Multiple windows” mode, or “Pre-trigger” if “Multiple level trigger” is set to true. It allows to capture and visualize up to 2 samples before the trigger condition is met.

Note that this option requires using additional logic resources for implementation.

2.2.7 Store trigger pulse: Enable or Disable

This setting allows to store the trigger pulse (when the trigger condition is met), so it can appear automatically as an additional captured data_line.

When “Store trigger pulse” = “Enable”, the number of sampled signals is then:

Input line count + 1

The user’s defined sampled bits being Input line count -1 downto 0, so the weight (index) of the trigger pulse in the captured flow is “Input line count”.

2.2.8 Store window number: Enable or Disable

When “Capture mode” is set to “Multiple windows”, the total capture depth is split in several capture windows. The length of each window is defined with the “Window capture length” parameter.

NXscope gives the user the ability to store the window number for each partial capture. This option can be helpful for visualization and identification of the several capture sets.


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When “Store window number” is set to “Enable”, four additional bits are stored in the capture memory, giving up to 16 different windows numbers (can be helpful to clearly identify each capture window when displaying the resulting waveform. The number of signals sampled by NXscope will be :

o “Input line count” + 4 if “Store trigger pulse” = “Enable”. In this case, the windows number are stored as :

(“Input line count” + 3 downto “Input line count”).

o “Input line count” + 5 if “Store trigger pulse” = 1”. In this case, the windows number are stored as :

(“Input line count” + 4 downto “Input line count” + 1).

2.3 Trigger configuration

2.3.1 Trigger line count: integer range 1 to 32

The trigger lines will be analyzed to find the trigger condition(s).

2.3.2 Trigger mode: “Basic” or “Basic & Edges”

The trigger lines will be analyzed to find the trigger condition.

There are two possible trigger modes:

- “Basic”: The following values detected for each trigger line are ‘0’, ‘1’ and ‘Ignore’

- “Basic & Edges”: The possible values are ‘0’, ‘1’, ‘Ignore’, ‘Rising edge’, ‘Falling_edge and ‘Both edges’

Note that “Basic & Edges” gives more trigger flexibility, but requires using more logic resources for trigger implementation.

2.3.3 Multiple level trigger: “Enable” or “Disable”

When “Capture mode” is set to “Pre-trigger” the user can define a two-level trigger condition. The analyzer will search first for the first level trigger condition, before searching for the second level and final trigger condition and start the data capture. For this, the “Multiple level trigger” must be set to true, and the “First level trigger value” must be defined by the user.

The NXscope IP Core output goes from low state to high when the first trigger condition has been met.

2.3.4 Trigger value:

When “Trigger mode” is set to “Basic”, each trigger line will be compared to the following possible values : ‘0’, ‘1’ or ‘Ignore’


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When “Trigger mode” is set to “Basic & Edges”, each trigger line will be compared to the following possible values : ‘0’, ‘1’, ‘Rising edge’, Falling Edge’, ‘Both Edges’ or ‘Ignore’

2.3.5 First level trigger value:

When”Multiple level trigger” is set to “Enable”, the pre-trigger condition must be specified too.

If this option is disable, the “First level trigger value” is ignored.

2.4 NXscope IP Core generation :

Once the NXscope parameters are set, press the “Generate” command icon in the bottom-right part of the window.

A new window appears. It allows to choose both file name and path.

A VHDL encrypted file is then generated. A header in clear VHDL (not encrypted) is available. This header appears as comments. It can be used for the component declaration when instantiating the NXscope IP Core in the design to be analyzed.


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3 NXscope capture tools

After compiling the design, the user must send the bitstream to the FPGA and then launch the data capture.

The user can launch the capture in two different ways :

3.1 With nxbase2 software:

Loading the bitstream :

>> nxbase2_cli –I –s /bitstream_path/bitstream_name.nxb

Launching a capture :

>> nanoxscope capture dump.txt 50E6 immediate=0 (for .txt format/ModelSim)

or

>> nanoxscope capture dump.vcd 50E6 immediate=0 (for .vcd format/GTKwave)

Where 50E6 is the estimated frequency of the sample frequency for this example (50 * 10**6 = 50 MHz in this case).

The frequency value doesn’t have any impact on the acquisition. It’s just used for the generation of the VCD file, if this format is choosen.

Note that if “immediate” = 1, the predefined trigger condition is ignored and the acquisition starts immediately.

If required, the user can chose the path to save the captured results.

3.2 Using NXboard GUI:

At the prompt, launch the following command:

>>nxboard

NXboard GUI appears:


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By selecting the “Bitstream” icon (on the left side of the GUI), the user can browse through the folders and choose the bitstream to be sent to the FPGA.

Note that if the FPGA is already configured, it must be reset by the JTAG chain before being re-configured with a new bitstream.

After the FPGA has been loaded with the bitstream containing the NXscope, select the “Scope” icon (left side of the GUI) to enter the capture command.


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The path and file name can be chosen. Press the “Capture” icon to arm the trigger and launch the capture.

Note that the value given to the “Capture Frequency” is taken in account only for the VCD file generation if this format is chosen.

A message will be issued after the captured data has been stored in the specified file.

3.3 NXscope results format:

NXscope can store the captured results in two possible formats :

- .txt : preferred format for waveform display on ModelSim/QuestaSim

- .vcd : preferred format for waveform display on GTKwave – free software

3.4 NXscope capture sequence:

After configuring the FPGA with the bitstream containing the NXscope IP Core and before launching the NXscope capture command, the “DONE” and ‘TRIG_ARMED” output pins of the NXscope IP Core are low. The IP Core is waiting for a command.

When launching the capture, the “TRIG_ARMED” goes high. The NXscope IP Core is waiting for the trigger condition(s).

When the trigger condition is found, the capture starts, the “TRIG_ARMED” output pin goes low, and the data capture starts.

After filling the assigned internal RAM the capture stops and the “DONE” output goes high. At this time, the NXboard / NXbase2 software starts reading the captured data via ANGIE USB-JTAG adapter. A message appears on the console to inform that reading is complete.

A new capture can then be started if required.

Important note : If the trigger condition is not met, the acquisition never resumes, and the software (nxbase2 or nxboard) stays waiting indefinitely.

In order to prevent such situation, it’s possible to use the optional input pin of the NXscope IP Core “TRIGGER_IMMEDIATE”. This pin must be tied to low state in normal situation. When it goes high, an immediate acquisition is started, ignoring the trigger condition(s).


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4 NXscope capture and display example

4.1 Launch NxBase2/NXboard and NXscope commands

In order to sample the data lines, you must use the Angie USB-JTAG adapter, and the NXbase2 software or NXboard GUI.

The bitstream must be first loaded, then the capture can be launched as specified in the previous chapter.

For detailed information about the available commands please refer to the NXbase2 user’s manual.

Once the data has been captured an ACSII file is generated (.TXT or .VCD). The results can be then analyzed in the ModelSim waveform viewer (.TXT result file), with a simple testbench or with the free GTKWave waveform display software using the .VCD result file.

4.2 Display and analysis of the captured results

4.2.1 Open ModelSim and launch the testbench simulation

As mentioned previously the ModelSim waveform viewer can be used to visualize and analyze the captured results (.TXT result file).

The .TXT file generated with the sampled results is read by a simple testbench, to be converted to graphic waveforms.

Have a look on the following example :

library ieee;

use ieee.std_logic_1164.ALL;

library STD;

use STD.textio.all;

use ieee.std_logic_textio.all;

entity TB_NXscope is

end TB_NXscope;

architecture TB_ARCHI of TB_NXscope is

signal CLK : std_logic;

signal SAMPLES: std_logic_vector(25+1 downto 0);

signal DIN : std_logic_vector(10 downto 0);

signal DIN_VALID : std_logic;

signal DOUT : std_logic_vector(11 downto 0);

signal DOUT_VALID : std_logic;

signal TRIG_PLS : std_logic;

Libraries declarations

Testbench entity

Signals declaration

begin

process

file RESULT : text;

Main process reading the


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variable LINE_VAR : line;

variable DVAR : std_logic_vector(25+1 downto 0);

begin

file_open(RESULT, "dump.txt", read_mode);

while not(endfile(RESULT)) loop

wait until rising_edge(CLK);

readline(RESULT, LINE_VAR);

read(LINE_VAR, DVAR);

SAMPLES <= DVAR;

end loop;

file_close(RESULT);

wait;

end process;

“dump.txt” result file

Values read are assigned to the “SAMPLES” signal

process begin

CLK <= '0'; wait for 10 ns;

CLK <= '1'; wait for 10 ns;

end process;

DIN <= SAMPLES(10 downto 0);

DIN_VALID <= SAMPLES(11);

DOUT <= SAMPLES(23 downto 12);

DOUT_VALID <= SAMPLES(24);

TRIG_PLS <= SAMPLES(25);

end TB_ARCHI;

Clock waveform

“SAMPLES” is split to several signals to restore the original ones

The user can then set its own waveform settings.

4.2.2 Open the .VCD result file with GTKWave and view/analyze the captured results

GTKWave is a free waveform display software. It allows to display the waveform of signals that are stored in .VCD format.

Please, refer to the GTKWave documentation for detailed information.


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5 NXscope IP Core configuration examples

The following shows three different examples of NXscope configurations.


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5.1 Example 1 : 12K x (25 + 1) capture with 50 samples pre-trigger condition

Number_of_trig_lines = 4 Input line count = 25 Capture depth = 12K Capture mode = Pre-trigger Pre-trigger samples = 50 User data delay = 0 Store trigger pulse = Enable Trigger line count = 4 Trigger mode = Basic Multiple level trigger = Disable Trigger value = 1, 0, Ignore, 1 Functional block diagram


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5.2 Example 2 : 24K x (33 + 1) capture (2 samples pre-trig cond)

Number_of_trig_lines = 6 Input line count = 33 Capture depth = 24K Capture mode = Pre-trigger User data delay = 2 Store trigger pulse = Enable Trigger line count = 6 Trigger mode = Basic & Edges Multiple level trigger = Enable Trigger value = 0, X, 1, R, 1, 1 First level trigger value = F, 1, 0, X, 1, R, Functional block diagram


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5.3 Example 3 : 8K x (42 + 1 + 4) capture (2 samples pre-trig cond)

Number_of_trig_lines = 8 Input line count = 42 Capture depth = 8K Capture mode = Multiple windows Window capture length = 1024 User data delay = 2 Store trigger pulse = Enable Store window number = Enable Trigger line count = 8 Trigger mode = Basic Trigger value = 0, 1, 1, X, 1, 0, X, 1 Functional block diagram


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6 Known issues

Erroneous single sample in the captured stream : Depending on NXscope settings, a dummy sample can be inserted into the captured stream. This sample can appear anywhere in the waveform. Fortunatelly, it’s easy to recognize, and it must be ignored. This “fake” or “pseudo” sample always exhibits all bits to ‘0’. It must be ignored. The following figure shows an example of the display artifact caused by this erroneous sample in the captured stream.

NanoXplore is working to correct this problem as soon as possible.


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7 How to order a NXscope license

NXscope license is not included in the “”nxmap” software. A separate license must be ordered. Please contact [email protected]

mailto:[email protected]

Documents

NanoXplore NXscope user manualNote that in the current version, all settings including trigger conditions are purely static. Any modification requires a re-generation of the NXscope