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ADP2230 is a mixed signal oscilloscope (MSO) for professional engineers. It includes analog inputs, analog output, and digital I/O, with deep memory buffers all operating at up to 125 MS/s. Users can receive and generate digital signals to test and analyze data from various devices while simultaneously powering those systems with its robust power supply. The ADP2230 performs the functions of several test and measurement devices and can replace a stack of traditional instruments.
With the included WaveForms software, users can view and capture complex data, perform spectral and network analysis, and quickly retrieve large amounts of data. WaveForms leverages the ADP2230’s deep buffer memory, allowing hundreds of millions of samples to be stored and streamed back to the host computer. WaveForms’ friendly user interface has the feel of traditional benchtop oscilloscopes.
Features:
When it comes to temperature measurement, thermocouples stand out as a favored solution owing to their affordability, simplicity, and expansive measurement range. In this article, we'll explain the intricacies of accurate thermocouple measurements, the innovative approach of the Digilent MCC 134 DAQ HAT in tackling these challenges, and how users can optimize their measurements to minimize errors.
Understanding Thermocouples: How They Operate
Thermocouples function by harnessing the Seebeck effect, where thermal gradients generate electrical potential differences. Typically consisting of two wires made of dissimilar metals joined at one end to form a junction, thermocouples produce a voltage in response to temperature variations, facilitating temperature measurement.
Various thermocouple types utilize different metal combinations, catering to distinct temperature ranges. For instance, J type thermocouples, crafted from iron and constantan, excel in measuring temperatures ranging from -210 °C to 1200 °C, while T type thermocouples, employing copper and constantan, are ideal for measurements spanning from -270 °C to 400 °C.
The challenge lies in accurately measuring the temperature difference between the hot (measurement) and cold (reference) junctions, which necessitates precise assessment of the cold junction temperature.
Navigating Thermocouple Measurement Fundamentals
Thermocouples generate a voltage relative to the temperature gradient between the hot and cold junctions. However, determining the absolute temperature of the hot junction requires knowledge of the absolute temperature of the cold junction.
Traditionally, ice baths served as reference points for the cold junction temperature. However, modern measurement devices incorporate sensors to gauge the terminal block's temperature, where thermocouples connect to the measurement apparatus.
Identifying Sources of Thermocouple Errors
Numerous factors contribute to thermocouple measurement errors, including noise, linearity, offset error, the thermocouple itself, and the measurement of the cold junction temperature. While advanced 24-bit measurement devices leverage high-accuracy ADCs and design strategies to minimize errors, thermocouple imperfections remain inevitable.
Addressing Design Challenges of the MCC 134 DAQ HAT
The MCC 134 encounters distinctive design hurdles in ensuring accurate temperature measurements. The MCC 134 faces uncertainties due to temperature gradients induced by external factors like the Raspberry Pi and ambient conditions.
To mitigate inaccuracies, Digilent redesigned the MCC 134 with an enhanced scheme featuring two terminal blocks and three thermistors strategically positioned to track cold junction temperature variations effectively.
Optimizing Thermocouple Measurements with Digilent’s MCC 134
To maximize the accuracy of thermocouple readings using the MCC 134, users should adhere to certain best practices:
In Conclusion
Despite the inherent complexities of thermocouple measurements, the MCC 134 stands as a testament to innovative design and rigorous testing, offering a reliable solution for leveraging standard thermocouples with the Raspberry Pi platform.
Dual mode is a new feature recently unveiled in WaveForms, coinciding with the launch of Analog Discovery 3 . This addition enables users to connect two identical Mixed Signal Oscilloscopes, synchronizing their acquisitions to double the channel count of their acquisition system. This functionality isn't limited to just analog inputs; it extends seamlessly to analog outputs and digital inputs and outputs.
This feature also supports the Analog Discovery Pro 3000-Series, where users can connect two ADP3450s to create an impressive 8-channel scope system. The specific hardware connections required may vary, but for 3000 Series devices, a pair of short coax BNC cables will suffice for the connection.
In this post, we'll guide you through the setup of Dual mode using a pair of AD3 devices and configuring the system to account for clock delay. It's important to note that this feature is supported in version 3.20.1 of WaveForms, the latest release at the time of writing. Additionally, there are some enhancements available in the beta version of WaveForms, 3.20.15, which introduces degree units as a phase adjustment option, and this guide refers to these improvements. You can access beta versions through the Digilent Forum link.
GUIDE:
Hardware Setup
To utilize Dual mode effectively, you must connect the external trigger pins of the two devices. Connect T1 to T1 and T2 to T2. T1 carries a reference clock between the devices, ensuring they use the same clock source, while T2 passes the selected trigger source between them for synchronized acquisitions. Ground connections between the devices should also be established to minimize crosstalk. If you want to further reduce crosstalk, consider using a twisted wire pair for the T1 reference clock signal. Keeping cable lengths as short as possible ensures optimal performance.
Software Setup
Choose the host device, noting that the selection of the first device does not impact functionality.
Click on the "Select + Dual" option and choose the second identical device. Follow the instructions to connect Trigger 1 to Trigger 1, Trigger 2 to Trigger 2, and a ground pin between the two devices.
Open the Scope instrument.
You'll now see a secondary set of analog inputs from the additional device, labeled as Channel 3 (+1±) and Channel 4 (+2±) for a pair of Analog Discovery 3s. Below the screen, you'll find indicators displaying the selected devices, additional device settings, and device status, in that order.
Despite the synchronization of the two devices with a reference clock and trigger line, there might still be some phase differences due to propagation delay. Without adjustments, the same signal sent to both devices may exhibit a delay, typically around 2.5ns.
To rectify this, provide a phase adjustment through the "Phase" setting in the Device Options dropdown (the 100 MHz button) at the bottom of the window. This allows you to manually fine-tune the clock for the second device, aligning data sampling with respect to the clock edge. This adjustment compensates for the delay from one device to the other, ensuring data is sampled at approximately the same time.
For precise phase offset selection, employ a shared signal source to test the system. A square wave works well for this purpose, as it facilitates the comparison of rising edges.
Zoom in closely on the trigger point, enabling you to determine the nanoseconds of difference between the primary and secondary device as they cross the same threshold.
Adjust the Phase dropdown in the Device Options until both devices cross the threshold at nearly the same time, fine-tuning until you achieve your desired results.
Keep an eye on the reference clock option, as it allows you to modify the clock's frequency passed over the T1 trigger line. Different frequencies may perform better or worse based on your specific application.
Throughout this process, remember that channel ranges can be adjusted to spread the signal vertically across the plot, making it easier to identify zero crossings.
After some experimentation, you can significantly reduce phase offset. For instance, we managed to reduce it to 247.7 ps out of a 10 ns clock period (100 MHz clock) for our setup, which is ten times better than the default settings.
Conclusion
With these adjustments, you now have access to an oscilloscope system capable of simultaneously sampling four signals, greatly expanding your testing capabilities.
This article details the differences in the new Analog Discovery 3 vs the Analog Discovery 2.
Lower Price than Analog Discovery 2
Backwards compatible with Analog Discovery 2 projects — so long as it didn’t use the 1.8 V input setting for digital pins.
Adjustable System Clock Frequency between 50 MHz and 125 MHz, allowing for up to a 125 MS/s simultaneous sampling rate on all channels for the analog inputs, analog outputs, and digital I/O.
All instruments always available in every configuration. No more losing access to digital I/O when allocating more buffer to the Wavegen.
USB Type C connection, USB 2.0 data rate. USB 3.2 Gen 1’s extra throughput didn’t add enough value in most applications.
Two differential 14-bit resolution analog inputs with 9 MHz bandwidth at -3 dB when using the MTE cables. Up to 16 bit resolution when sampling at 1/4 of the system clock frequency. ±2.5 V and ±25 V input ranges. Maximum sample buffer size doubled from 16k to 32k per channel (64k when only using 1 channel). Hardware FIR filters for each input. Record mode rate increased to 10 MS/s. Digital loopback of Wavegen and Power Supply output supported.
Two single ended ±5 V analog outputs with 14-bit resolution and 9 MHz bandwidth at -3 dB when using MTE cables. Maximum sample buffer size doubled from 16k to 32k per channel. FM/PM and AM/SUM buffers on each channel increased to a minimum of 2k samples with 16-bit resolution. Digital loopback of received Scope data supported.
16 digital I/O pins at 3.3 LVCMOS supporting 5 V inputs. Maximum sample size doubled from 16k to 32k per channel. All digital pins and the two trigger pins can have their Pull resistor configured.
– +5 V and -5 V power supplies now supply up to 800 mA (2.4 W) each. Integrated readback of the supplied voltage supported.
The new Digilent Analog Discovery 3 is a digital oscilloscope, logic analyzer, waveform generator, pattern generator, and much more. Using the included WaveForms software (supported by Windows, Mac, and Linux), the Analog Discovery 3 can be used in the lab, in the field, or even at home as any number of test instruments that you might have to buy separately on a traditional benchtop.
Like its predecessor, the Analog Discovery 3 is a portable USB-powered test and measurement device, though it now features an upgraded USB-C connection. It’s lightweight and small enough to fit in your pocket or backpack, so it becomes an exceptional companion for any engineer.
This iteration of our most popular Analog Discovery digital oscilloscope also allows engineers access to two new powerful features in WaveForms: the FIR (finite impulse response) Filter and the PID (Proportional Integral Derivative) Controller. Through the use of optional FIR filters on Oscilloscope input channels, users can reduce the amount of high frequency noise that could affect the quality of their measurements. The PID Controller allows the control of an output of a signal based on the response of your system.
Features:
Oscilloscope:
Arbitrary Waveform Generator:
Logic Analyzer and Pattern Generator:
Programmable Power Supplies:
Additional Features:
Additional software instruments including:
The 4-20 mA current loop interface came about because of the need to transmit information over long distances. System designers found that instead of a changing a voltage signal [that is susceptible to noise and voltage drops along the wires]they could transmit a changing current with little downside. For the most part, the information is simply a measurement or a value to control something. For instance, a factory process may need to transmit a pressure value up to the control room that is hundreds of feet away. Likewise, the control room my need to adjust the pressure by sending back a 4-20 mA signal to the pressure controller that is also hundreds of feet away.
Instruments that monitor the current level use a resistor to convert the current to voltage. The most common value is a 250-ohm precision resistor for a 1 to 5 VDC voltage drop. Ideally, a resistor for such purpose should have a 0.1% tolerance (or better) with a minimum power rating of 0.25 W and a temperature coefficient of at least 25 ppm/°C. Lower values of resistance, for example, 62.5 ohm [for a lower voltage drop within the loop of 0.25 to 1.25 VDC] will require that the instrument can adequately measure a value this low. For instance, an instrument that has a fixed 5 volt input will produce the best accuracy using the 250 ohm resistor because the voltage span consume most of the range.
Powering the Loop:
4-20 mA transducers typically specify an excitation voltage of between 9 and 30 volts. The excitation voltage must be greater than the sum of all the voltage drops in the loop – including voltage drops along the wires. If for example there are two monitoring processes, the voltage needs to be greater than 10 volts, otherwise error will occur at the upper range. Instead choose a power supply that has a greater value, 18 to 24 volts seems to be popular.
It’s best to use a differentially ended input across the resistor but single-ended can also be use if care is taken to avoid ground loops. In the picture below, if the power supply negative is the system ground and the DAQ and meter are isolated then single-ended will work. However, if the DAQ device is not isolated it will get its ground from the computer and there may be a voltage difference between it and the power supply negative. In this case it’s best to use a differential connection. If there is a large difference between the negative and the computer ground it’s best to use a DAQ device that has isolation.
Care should be taken as to where in the loop the measurement is made. If the DAQ input is sensitive to common mode voltage then put it as close to ground as possible. Elsewhere in the loop the inputs will have 5 or more volts of common mode. Isolated inputs work best in this case.
The Digilent MCC USB-201 provides eight analog inputs with a 100 kS/s sample rate, plus eight DIO and one counter input.
DPS3340 is a three channel variable DC programmable power supply. It allows users to control the power provided to external circuits. Providing both constant voltage and constant current modes with built in readback sensors and optional tracking for the output channels, users can confidently power circuits according to their requirements.
The included WaveForms software application enables the use of three programmable DC outputs. The software features a friendly user interface that has the feel of traditional benchtop software. The Discovery USB Programmable Power Supply communicates with WaveForms via a USB connection to your computer, allowing users to control the power supply outputs and enable overcurrent protections. In addition to the use of instruments in the application, the WaveForms application has a script editor tool, which allows custom scripting of the instrument in JavaScript. WaveForms is designed to be run on a laptop or desktop computer and is Mac, Windows, and Linux compatible. The DPS3340 can also be used with other Digilent Test and Measurement devices like the Analog Discovery Series of products.
For even more customization potential, the WaveForms Software Development Kit (SDK) can be used to create custom applications and scripts in Python, C, and additional languages. The Discovery USB Programmable Power Supply is also compatible with LabVIEW and the Digilent Toolbox add-on available for MATLAB.
DPS3340 specs:
Whenever you build a circuit or prototype, the first thing is to grab the necessary components and parts. Occasionally, a missing active or passive component causes a delay for the project. Having the electronic parts kit can prevent this problem. Parts Kits also provide a useful selection of parts that are the building blocks of all electronics.
Texas Instruments myParts Kit
myParts KitmyParts Kit comes with a collection of parts including op-amps, an instrumentation amplifier, voltage regulators, switching regulators, digital logic gates, timers, temperature sensors, data converters, transistors, resistors, capacitors, LEDs, switches, a wiring kit, and more. With myParts Kit, you can create projects in areas such as power management, audio amplification, spinning motors, light detection, and signal conditioning.
Amplifiers:
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Regulators:
| Diodes:
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Logic ICs:
| Transistors:
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Passive components:
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Digilent has officially launched their new Analog Discovery Pro model ADP3450 with a price of $1295 US. The Analog Discovery Pro ADP3450 is a professional bench-top tool which includes a wide variety of features. This might not be the cheapest option for the Maker type, but it does look like a nice mid range tool for more of a professional or consulting application.
It would make for a cool RoadTest though.
Some of the features include:
Analog Inputs:
Analog Outputs:
Digital Inputs and Outputs:
Connectivity:
Software
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First, I would like to thank element14 for providing me one of the ten boards for the Arty-s7 series webinar. I was glad to be a part of the webinar and attended all three. I was also learning FPGA because of their several advantages and flexibility they provide. When I started, I just had thought that FPGA's can emulate the Microcontrollers. It can just become a microcontroller with users loading .bitstream file onto them, which contains the entire complied design of a Microcontroller. It also has many advantages and features to offer. I would like to list some of the advantages of FPGA's.
The webinars for Arty-s7 had three parts:
The Arty-s7 comes with Spartan-7 FPGA from Xilinx. The spartan FPGA from Xilinx provides many latest features and supports Vivado 2017.3 and newer. It has Arduino connectors and also P-mod connectors for a more streamlined design experience. Arty-s7 is designed to be Microblaze ready and comes with ready to use free Xilinx webpack licensing with the Vivado design suite.
The Installation of the Vivado is not that trivial. You can also choose between Windows or Linux platforms.
There could be a larger download depending on the packages you select.
The first webinar was about the installation of Vivado. The second part was about running the basic Hello_world program.
In this blog, I will first explain how I have run the last project, which was about interfacing and accessing sensor values from the P_mod_NAV sensor.
For Lab3 the first step was to start the Vivado IDE and make a design with Microblaze.
The Lab2 has already explained in detail the design with Microblaz and run the hello_world application.
So when you open the Vivado your Block diagram should look something like the following screenshot.
The next step is to install the IP's(Intelectual Property) from the repository.
These IP's will have block and design files, as well as documentation for each of the IP's, downloaded in a .zip file.
https://github.com/Digilent/vivado- library/archive/v2020.1.zip
Next, go to the Project->Settings->IP->Repository and click on the + icon and navigate to the downloaded repository containing IPs.
This will add about 66 IP's and 4 Interfaces.
Now, it is time to edit the block design and add the P-Mod_NAV block into the existing Microblaze design and make the necessary connections.
First, add the block by clicking on the + icon and searching for the pmodNAV. Then run the connection automation which will automatically connect the Pmod_NAV to the Microblaze design.
Then connect all the interrupts as shown in the lab_3 pdf(step15).
The final block design should look like the following.
The next step will be to validate the block design and generate the bitstream. Once the bitstream has been generated, a window will open with few options. Click on cancel.
Next, go to the File->Export Hardware, then click yes to overwrite the module file.
Next, Launch Vitis IDE from the tools->Launch Vitis IDE menu.
Create a new application named lab3. Click next
Then go the create a new platform from hardware and select the newly created .xsa file.
Create an empty application and click finish.
Now, the Lab3 download from the webinar link already contains the main file to be used to run the example code. Copy that file to the newly created Vitis application.
In the /src folder you should be able to see the main.c file.
Next, open the file in Vitis IDE.
Next, open the terminal to view the output.
Then connect the Pmod_NAV in the JA connector.
select P-modnav_ststem from Vitis IDE and click on Build.
select from the Xilinx-> Program FPGA.
Then Run->Run As-> Launch Hardware to view the sensor values.
Enjoy!!
