Lotus D100006 Digital Step Attenuator User Manual
- June 5, 2024
- LOTUS
Table of Contents
Lotus D100006 Digital Step Attenuator
INTRODUCTION
Lotus Digital Step Attenuator (DSA) User Manual provides general introduction,
installation instructions and operation for Lotus USB programmable attenuators
that include single and multiple channels.
Lotus Communication Systems, INC. (LOTUS) has developed single and multiple
channel programmable attenuators, which can be controlled via standard USB.
Programmable Attenuator can operate up to 40 GHz with minimum attenuation
resolution of 0.25 dB.
Model Section Guide
Model Name
| No. Of Channels| Frequency Range| Attenuation Range (dB)| Attenuation Resolution| Max Input Power (dBm)|
Control Protocols
---|---|---|---|---|---|---
A1Q9K6G32
| 1| 9KHz-6GHz| 31.75| 0.25| +28 dBm| USB
A1Q9K6G64| 1| 9KHz-6GHz| 63.5| 0.25| +28 dBm|
USB
A2Q9K6G64
| 2| 9KHz-6GHz| 63.5| 0.25| +28 dBm| USB
A4Q9K6G64| 4| 9KHz-6GHz| 63.5| 0.25| +28 dBm|
USB
A8Q9K6G64
| 8| 9KHz-6GHz| 63.5| 0.25| +28 dBm| USB
A1Q9K8G32| 1| 9KHz-8GHz| 31.75| 0.25| +28 dBm|
USB
A1Q9K8G64
| 1| 9KHz-8GHz| 63.5| 0.25| +28 dBm| USB
A2Q9K8G64| 2| 9KHz-8GHz| 63.5| 0.25| +28 dBm|
USB
A4Q9K8G64
| 4| 9KHz-8GHz| 63.5| 0.25| +28 dBm| USB
A8Q9K8G64| 8| 9KHz-8GHz| 63.5| 0.25| +28 dBm|
USB
SOFTWARE SETUP
For Windows 10 and Linux, the USB Drivers will be installed automatically. For other Windows operation systems, we need to install the USB driver.
Application Software
Lotus programmable Attenuator does not need to install any software. Lotus provides an executable (Windows Certified Program) file DSA.exe to download on our web site. User can add shot cut to this executable program on the desktop in order to quickly access this control program.
USING LOTUS DSA GUI
All LOTUS attenuator models share the same GUI interface to allow easy control. To start the program, double click DSA icon and get started!
Starting the DSA GUI
Startup Screen
When the DSA GUI is started, it will show the connect options to allow user to
choose USB Serial Com Port or Ethernet Control.
USB Serial Com Port
LOTUS Attenuators are driver-less USB HID compatible device that uses virtual
serial com port as an interface to user control. After user click OK button to
select USB Serial Com Port, the USB Serial Port Configuration Screen will pop
up to show the available LOTUS USB device to choose. Figure 2 show an example
USB Serial Port Configuration Screen that has two Lotus USB Attenuator
Devices.
When the available USB DSA device is shown, it will list the DSA Part Number,
Serial Number and what Com port is connected.
For example, the selected Attenuator in Figure 2 shows Attenuator with PN:
A1Q9K8G64 with SN: 194501 and is connected to COM7.
After user selects the DSA attenuator and click OK, the Attenuator Control GUI
will show. The Attenuator Control GUI is configured automatically based on
number of channels available for the DSA attenuator. Figure 3 shows the GUI
for one channel. Figure 4 shows the GUI for two channels. Figure 5 shows the
GUI for four channels. Figure 6 shows the GUI for eight channels.
Control Attenuator with GUI Program
The main screen of the DSA control GUI will appear after user selects the
desired attenuator. In this section, we will illustrate how to use GUI to
control Attenuator. We will use single channel as an example. When the control
is related to multiple channels, we
will add multiple channel examples.
Figure 7 shows a GUI for single channel with 63.5 dB attenuator control range.
Main GUI Screen Functions:
| # | Name | Descriptions |
|---|---|---|
| 1 | Model Description | Display PN, SN, Firmware Version |
| 2 | Current Attenuation | Display the current attenuation |
| 3 | Manual Attenuator | Attenuation to be set. The value can be either |
changed by typing a value, or using the scroll bar and up/down arrows to
change the attenuation
4| Step Sweep Control| When this Notebook is selected, allows setting an
attenuation sweep with user defined start, stop, step and dwell time values
5| List Sweep Control| When this Notebook is selected, allows setting a
table (or list) of user defined attenuation and dwell time for list sweeping
6| SCPI Command Window| When this Notebook is selected, allows user
input SCPI command to directly control the attenuator
7| Sweep/List Direction| This allows user to select either Up, Down or
Bi-Direction for Step/List Sweeping
8| Sweep Duration/Cycle| This allows user to select either Continuous,
Duration or Number of Cycles for Step/List Sweeping
9| PC/Firmware Control| This allows user to select either high speed
Step/List Sweep using Firmware control or PC control
10| Start & Stop| Start and Stop the automatic Step/List Sweep at the
current attenuation setting.
11| Dwell Time| This allows user to select Dwell time for Step Sweep
12| File Dropdown Menu| This allows user to select Dropdown Menu to
Change the Device or clear the SCPI command window
STEP AND LIST SWEEP FUNCTION
The GUI provides the ability to carry out an automatic Step Sweep or list sweep.
Step Sweep
In Step Sweeping, the Attenuator will sequentially sweep from a start attenuation value (default 0) to a stop value (default maximum attenuation value), with a fix step size (default minimum step size) and dwell time.
In order to configure Step Sweep, user needs to select “Sweep Control” Tab in the middle of the GUI. Then the user needs to make sure the desired channel is selected by the checkbox. Then user can select Start, Stop and Step Attenuation (dB) by typing or use the Up/Down Arrow.
After user selects the Start, Stop and Step Attenuation as shown in Figure 8, he/she can then select Sweep Direction, Sweep Duration/Cycle and Dwell Time using Sweep/List Control Window as shown in Figure 8.
List Sweep
In List Sweeping, the Attenuator will sweep from a List sequence of attenuation and dwell time value based on user input List table.
| # | Name | Descriptions |
|---|---|---|
| 1 | List Attenuation for Channel | User Input for Attenuation Value for |
Individual Channel
2| List Dwell Time| User Input for Dwell Time value for all Channels
3| Save CSV File| User can save the List to CSV File
4| New File| User can start New List Grid File, when this button is
clicked, the input in the Grid Table will be cleared
5| Open CSV File| User can load CSV File (includes List) in the List
Grid Table
6| Active Channels| User Input to select Active Channel(s) for List
Sweep
The other List Sweep Controls are similar to those of Step Sweep Control. The only difference is that the Dwell Time Input is disabled in List Sweep Control since the dwell time is set in the List Grid Table instead. Figure 11 shows a List Sweep Control GUI for Eight channels. We can see that the List Grid Table is expanded to allow Attenuation Input for eight channels. The Active Channels window is also expanded to allow section of active channels for eight channels.
List Sweep CSV File Format
LOTUS List Sweep CSV File Format is as follows:
Lotus Communication Systems Inc
Programmable Attenuator Sweep List CSV File
Ver 1.0
1,1
10,1
20,1
30,1
40,1
The above file set the List attenuation sweep for attenuation value at 1, 10, 20, 30 and 40 dB and dwell time at 1 second for each attenuation. User can use other Tools (e.g. EXCEL) to edit the CSV file and load the file in the LOTUS List Grid Table in Figure 11.
PC Control
The PC Control Mode is the default mode for all LOTUS attenuation models. In the mode, the step sweep or list sweep is managed by the GUI program. Each attenuation value for each channel is sent to the attenuator one at a time using SCPI command.
Since the GUI program is the control, the program always knows exactly what attenuation is set for the Attenuator. Thus the GUI will display the current attenuation state for all the controlled channels. Since the GUI sends the manual SCPI command to the Attenuator, a communication delay is expected between the PC and attenuator. Typical communication delay is in the order of 5ms.
Firmware Control
In Firmware control mode, we can achieve much faster attenuation sweep than PC control. In this high speed firmware control mode, the Step Sweep or List Sweep parameters are first sent to the Firmware from PC GUI program.
After the Sweep parameters are communicated from PC to Firmware, no further communication is required (other than Sweep Stop). The Firmware on the Attenuator will take full control for Step Sweep or List Sweep. This enables high speed attenuation sequences with dwell time as low as 100us for one channel Attenuator. Each extra channel will add about 100us since the Firmware needs to send more SPI command to other channels.
LOTUS Attenuator uses the current start-of-art Microprocessors with 48MHz CPU clock and high speed SPI interface (12MHz) to achieve <100us Dwell time in the Firmware Control mode. The limitation of this minimum dwell time is the Attenuator SPI interface speed.
Please note that in this high speed mode, PC will not be able to display the current attenuator state since the communication delay between PC and Attenuator is much larger than the minimum dwell time.
SCPI COMMAND WINDOW
LOTUS Programmable Attenuator GUI also provides a SCPI Command Window for direct communication with Attenuator using LOTUS simplified SCPI commands or full name commands.
Figure 12. LOTUS SCPI Command Window GUI
Figure 12 shows an example SCPI Command Window GUI. This window is the Tab after List Control Tab. Figure 12 shows a “*IDN?” command was sent to Attenuator and Attenuator response with the Manufacture Name (LOTUS), Part Number (A1Q9K8G64), Serial Number (194501) and Firmware Version (1.0).
User can clear command window by select menu->Clear Terminal.
For details about the SCPI command, please refer to LOTUS document [3].
SCPI COMMAND
The following SCPI command can be typed through many tools. The example tools are:
- Keysight Connection Expert
- Putty
- Tera Terminal
| # | Name | Descriptions | Example Response |
|---|---|---|---|
| 1 | *IDN? | Identity | LOTUS,A1Q9K8G64,202301,v21.06.29 |
| 2 | SAVE | Save settings to Flash. Power up will retrieve saved settings. |
NA
3| PRESET| Set the DSA to default status Default is maximum attenuation|
4| ATTM FIX| Attenuator Mode FIX (1)
Sweep (2)
List (3)| NA
5| ATT 31| Set Attenuator Level to 31, only able to set in FIX mode| NA
6| ATT?| Query Attenuator Level| 31
The “*IDN?” command will list product company (LOTUS), product name (A1Q9K8G64), Serial Number (202301) and firmware version (v21.06.29).
Please note that Command 5 can only be used when Attenuator is in Fix Mode (ATTM FIX command is sent).
The Attenuator is set to maximum attenuation after power up. In order to set
at a different value after power up, please following sequence of SCPI
command:
Command 1). ATTM FIX
Command 2). ATT 31
Command 3). SAVE
After Command 3: SAVE is executed, the attenuator will be set to 31dB after
power up.
SCPI Command using PuTTY Software
In this section, we will describe how to use third party software PuTTY to send SCPI command to BUDC.
When BUDC is connected to Windows PC, it is automatically recognized as Virtual COM port. Figure 13 shows an example that the COM36 is recognized as the BUDC is connected to the PC. When the BUDC is disconnected from PC, the COM36 will disappear.
Figure 14 shows the default Serial Port Configuration window. BUDC Virtual COM port will use default Putty setting for communication. If you prefer Local Echo (you can see your typed SCPI command on the terminal) and Line Editing (you can edit the command), please refer to Figure 15. Figure 16 shows an example PuTTY command window and results from SCPI commands using COM31.
FIRMWARE UPDATE
LOTUS Attenuators feature an improved bootloader that makes it easier than ever to update firmware onto the attenuator. Instead of need drivers or a separate program for flashing new firmware (Jlink or others), user can simply drag a file onto a removable drive.
The first step to upload the Firmware is to triggering bootloader in the attenuator. It is easily done by double tapping the reset button when the attenuator is powered. In order to do this, the user will have to open the Attenuator to expose the Reset Button on PCB board.
Once the bootloader on Attenuator is active you will see the Attenuator Device will be reinstalled into Operation system as a removable drive. The installation is automatic. The new drive will appear on your computer as LOTUSBOOT.
Once the bootloader is successfully connected you can open the drive and browse the virtual file system. It should have three files:
- CURRENT.UF2 – The current contents of the microcontroller flash.
- INDEX.HTM – Links to Microsoft MakeCode.
- INFO_UF2.TXT – Includes bootloader version info. Please include it on bug reports for the Attenuator.
To update new Firmware, simply drag the new UF2 file onto the drive. After the file is finished copying, the bootloader will automatically restart. This usually causes a warning about an unsafe eject of the drive. However, it is not a problem. The bootloader knows when everything is copied successfully. You may get an alert from the OS that the file is being copied without its properties. You can just click Yes.
You may also get a complaint that the drive was ejected without warning. Don’t worry about this. The drive only ejects once the bootloader has verified and completed the process of writing the new code.
After dragging the new UF2 file and the firmware is updated!
Revision Notes:
Version
| Date|
Comments
---|---|---
A
|
12/11/2019
| First Full Version for Release.
B
|
06/30/2021
| Add SCPI Commands
References:
[1]. Keysight E8257D/67D & E8663D PSG Signal Generators
[2]. Standard Commands for Programmable Instruments (SCPI) 1993.0.
[3]. Lotus Digital Step Attenuator SCPI Command Manual
References
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