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Monday, October 29, 2012

Top 6 Trends in Test & Measurement

The new generation of consumer electronics devices converge Internet connectivity, wireless communications, high-fidelity audio and HD video into a single device. To keep up with the times, different strategies have been adopted by test and measurement manufacturers and design houses. Take a look ..
 1. FPGA-enabled instrumentation
With the increase in system-level tools for field-programmable gate arrays (FPGAs) over the last few years, an increasing number of manufacturers are including FPGAs in instrumentation. What’s more, engineers are given the choice to reprogram these FPGAs according to their requirements. So test engineers can embed a custom algorithm into the device to perform in-line processing inside the FPGA, or even emulate part of the system that requires a real-time response.

Satish Thakare, head-R&D, VLSI division, Scientech Technologies, explains the traditional challenges that led to this trend: “Designers and manufacturers have to face a lot of challenges to make the product available in the market in a short time. Using a hardware-based approach does not serve the purpose as the designer has to redesign the hardware for every product. Even conventional methods will not serve the purpose as it works on the sequential method. So the designers need a kind of technology that allows them to change the functionality without changing the hardware while being able to upgrade the product on the go.”

Thakare goes on to explain the solution: “The obvious choice for the designer is to use reconfigurable hardware, i.e., FPGA. A benefit of using the FPGA in the instruments is that it offers high reliability, low latency, reconfigurability, high performance, embedded digital signal processor (DSP) core and true parallelism.”

Apart from digital functions, some FPGAs have analogue features. Some mixed-signal FPGAs may have integrated analogue-to-digital converters and digital-to-analogue converters.

Mahendra Pratap Singh, business development manager, TTL Technologies, adds, “Logic blocks can be configured to perform complex combinational functions and also include memory elements, which can be simple flip-flops or more complete blocks of memory. The architectural flexibility, customisation flexibility and cost advantage put FPGAs ahead of complementary technologies.”

The most common test instrument in the industry with this capability is the digitiser, which allows faster processing of digitised data.


2. Wireless standards outbreak

As new wireless standards like the WLAN 802.11ac, WiMAX, LTE and high-throughput 802.11ad roll out, it becomes even more challenging for test engineers in India and around the globe. Bharti Airtel has already launched its 4G service in Kolkata, making India one of the first countries in the world to commercially deploy this cutting-edge wireless technology. As RF and wireless applications expand to become general-purpose, the instrumentation segment might also begin to mirror this trend with the adoption of RF instrumentation to such a level that it becomes as important as our digital multimeters.
A common problem that test engineers face with the explosion of different standards is that they have to continuously set up different test platforms for each standard. 
Sadaf Arif Siddiqui, technical marketing specialist at Agilent Technologies, provides more insight: “A test engineer working on fast emerging standards may have to bear the pain of setting up different test instruments and different test platforms or software. Moving to an easy-to-use, upgradeable and multi-standard vector signal analysis software and instruments such as X-series analysers will reduce this pain and test times to a large extent, thereby optimising the test time and costs.” 

3. Increased use of wireless devices at the workplace
Tablet computers and smartphones have become so popular that they have a significant presence at the workplace too—not as devices under test but as part of the test system. While the computing power made available by these devices is notable, they cannot replace the PC and related measurement platforms like PXi. Instead, these devices are suitable for data consumption and report viewing, and system monitoring and control.

National Instruments’ Automated Test Outlook 2012 explains: “The explosion of mobile devices like tablets and smartphones provides compelling benefits to engineers, technicians and managers involved in automated test who need remote access to test status information and results. While today’s technology offers solutions for monitoring or remote reporting via mobile devices, test organisations will need new expertise to unite the networking, Web services and mobile app portions of the solution.”

4. Software-defined instrumentation
As the complexity of products continues to increase, their testing becomes much more challenging. Test engineers now require test systems that are flexible enough to support the wide variety of tests that must be performed on a single product while being scalable enough to encompass a larger number of tests as new functionality continues to be added.

“Increasingly, the functionality of complex devices is being defined by the software embedded in them. This is challenging for many test engineers because most standalone instruments cannot change their functionality as fast as changes in the device under test (DUT) due to the fixed user interface and firmware that must be developed and embedded in the instrument. Thus test engineers are turning to a software-defined approach to instrumentation, so that they can quickly customise their equipment to meet specific application needs and integrate testing directly into the design process,” says Eric Starkloff, director of NI Test Product Marketing.

Thakare shares two major advantages of software-defined instrumentation: “First, it can dramatically reduce the number of hardware components in all the mixed-signal designs, which means smaller chip size for system-on-chip implementation. Second, it can provide automatic adjustment or compensation for circuit component variations due to temperature dependence, ageing and manufacturing tolerances.” 
Software-defined instrumentation looks to become an essential component of scalable and highly performing test systems. Singh agrees by saying, “We predict a bright future for software-defined instrumentation. Software-defined instruments, also known as virtual instruments, are modular hardware with user-defined software giving the flexibility to combine standard and user-defined measurements with custom data processing using common hardware components. This flexibility is useful for electronic devices like advanced navigation systems and communication devices like smartphones to integrate diverse capabilities and adopt new communication standards.”

5. Use of multicore and parallel test systems
As the complexity and functionality of electronic devices grow exponentially (in sync with Moore’s law), so does the cost of testing them. Minimising the cost of test can be challenging, but one way is to test more with less. The inherent parallelism that is made available by the graphical programming paradigm of software like LabVIEW from National Instruments and FlowStone DSP from DSP Robotics helps engineers immediately benefit from multicore processors and overcome the complexity associated with traditional text-based languages.

The trend of increasing clock speed to get better performance ended back in the early 2000s. Since then, processor manufacturers have implemented alternate technologies to ramp up performance while keeping the clock speeds around 3 GHz. These technologies include the use of processors with multiple cores on a single chip, hyperthreading, wider buses and hyper transport. Moreover, the advancement of the process node to the current 22nm process by utilising 3D transistors has resulted in significantly faster, leaner and more efficient processors for use in embedded controllers and modular instrumentation.

Denver D’Souza, senior technical consultant at National Instruments India, says, “The reality that transistor density doubles every 18 months has led to significant advances in the performance of electronic devices. This is evident not only in the latest Intel Core i7 processors but in the shrinking of technology such as 64GB solidstate drives, which are now the size of a postage stamp. These technological advances translate into considerable cost reductions.”

6. Merging of EDA tools and hardware test platforms
The extremely competitive environment in which electronics companies work now is shown by how next-generation communication protocols are barely labeled as standards before they can be seen in the market. For instance, the 802.11ac solutions have already been brought out by Broadcom even though it is yet to be ratified. In situations like these, companies go all out to get a jumpstart on the competition, and what better way to do this than to merge design and testing in order to accelerate the ‘time to market’.

Adesh Jain, applications consultant at Agilent Technologies, explains why the traditional method is slow: “Traditionally, for any complete electronic product to be ready for the market, each component of the complete system is first designed and verified with EDA tools, then prototypes are fabricated and tested, before the final product is released to the market. If discrepancies are found in the hardware at later stages, the whole cycle has to be repeated, which would result in loss of time as well as money for any organisation.” 

Proper verification at earlier stages reduces this time and effort to a great extent. The tests, specs, algorithms and plots used in the early stages of EDA are the same as measured on the test bench. The aim is to merge both the worlds and see if it is possible to save the design engineers’ time by streamlining the flow and thus improve productivity while reducing the time to get the product out to the market. 

How to Create and Submit Your Blogger Sitemap to Google

It is very important to generate and submit blogger sitemap to Google, Yahoo and Bing. But here a question arises that what is a sitemap? A sitemap is a digital map of all your contents on a blog or website. It is important to create such a sitemap which can be easily understand by search engines.

If you have added your sitemap to Google Webmaster Tools then all your contents will be indexed by Google and they may appear in search results very frequently. There are various types of sitemaps like rss.xml sitemaps, atom.xml sitemaps, video sitemaps, etc. But here I will tell only atom.xml sitemap, because it is very easy to generate and submit. Follow the below steps to start.

1. To submit your sitemap to Google sign in to Google Webmaster Tools. I am assuming that you have verified your blog ownership.

2. Select your blog and on the left side click Site Configuration >> Sitemap and click the red button on the right side which says Add/Test Sitemap.



3. Copy/Paste the below sitemap in the box.

• atom.xml?redirect=false&start-index=1&max-results=500

Click submit and you've done. It will take time to index all your posts. Once it is verified you will see your submitted and indexed webpages in blue and red colors as seen in the above image.

Now a very important thing you should keep in mind. The above sitemap generated is only for 500 posts. After every 500 post you have to submit a new sitemap. See below examples.

• Sitemap for less than 500 posts.

• atom.xml?redirect=false&start-index=1&max-results=500

• Sitemap for more than 500 posts but less than 1000 posts.


atom.xml?redirect=false&start-index=501&max-results=500

•  Sitemap for more than 1000 posts but less than 1500 posts.

atom.xml?redirect=false&start-index=1001&max-results=500

From above example you can see that after every 500 post you have to submit a new sitemap in addition to old sitemaps so that all your post should get indexed by Google.

Saturday, October 27, 2012

Wireless Equipment Control Using AT89C51


Here is a microcontroller based wireless equipment controller that can switch on or switch off up to four devices at a desired time interval set by the user in the transmitter. The devices can be controlled remotely from a distance of up to 30 metres from the transmitter. In the transmitter, an  LCD module is used to show the device numbers and preset control time for the devices (00 to 99 seconds). Concepts of wireless RF communication and automation with AT89C51 microcontroller are used here. 

The system is small, simple, cost-effective and good for wireless control of home appliances or industrial instrumentation.

Block diagram

The system comprises a transmitter and a receiver as described below.





Four pushbutton switches (S1 through S4) are used as inputs to select the devices and set the time-out in the transmitter section. These are designated as up, down, enter and run keys, respectively. The time-out data is transferred over the RF wireless link to the receiver section.


The 8-bit AT89C51 microcontroller is the main controlling part of the transmitter section. It is connected to the LCD module, input switches and encoder IC (HT12E). The device control program is stored in the memory of the microcontroller to control the devices as per the time-out settings  done through input switches S1 through S4.


A two-line, 16-character LCD module shows the status of the main program that is running inside the microcontroller.

The HT12E is an 18- pin DIP package encoder IC that encodes 4-bit data and sends it to TRX-434 RF transmitter module.
The TRX-434 RF transmitter module uses a digital modulation technique called amplitude-shift keying (ASK) or on-off keying. In this technique, whenever logic ‘1’ is to be sent, it is modulated with carrier signal (434MHz). This modulated signal is then transmitted through the antenna. The waveforms in Fig. 2 depict the ASK concept. 

fig2
Receiver section. Fig.3 shows the block diagram of the receiver section.

The 12V DC supply, used along with a 5V regulator, can be provided by a 12V battery or power adaptor.

The RX-434 radio receiver module receives the ASK signal from TRX-434. The HT12D decoder demodulates the received address and data bits. IC CD4519 is a quadruple two-input multiplexer that selects the appropriate data bits to control the devices.
fig3
The ULN 2003 relay driver consists of seven npn Darlington pairs that feature high-voltage outputs with common-cathode clamp diodes for switching the inductive loads. The collector-current rating of a single Darlington pair is 500 mA.
Circuit description
Transmitter circuit. Fig.4 shows the transmitter circuit. The microcontroller reads the input data from switches S1 through S4 at its port-2 pins 21 through 24 and displays it on the LCD. Port 3 provides read data to the encoder IC HT12E at pins 10 through 13. The microcontroller is programmed to control input and output data.

When the push button switches (S1 through S4) are open, logic ‘0’ is constantly fed to the respective port pins of the microcontroller. When any of the buttons is pressed, logic ‘1’ is fed to the respective port pin of the microcontroller.
fig4
The device control program stored in the memory of the microcontroller activates and executes as per the functions defined in the program for respective input switches.

Data inputs AD8 through AD11 (pins 10 through 13) of HT12E are connected to the microcontroller. Pins 1 through 8 (A0 through A7) of the IC are address inputs. Shorting them address pins using switches to either Vcc or Gnd enables different address selections for data transmission. Here we have connected them to 5V. Since address pins are connected to 5V, the address is set to 255d (in decimal). If you were to connect all the address pins to ground, the address would be 000d. Thus there are 256 possible addresses available. So you can set up switches to control one or more of the encoder address pins.

Pin 14 is a transmit-enable (TE) input pin. The encoder will send data only when pin 14 is connected to ground. Whenever a button is pressed, logic ‘0’ is sent to this pin through the microcontroller, thus activating it and enabling transmission.

Pin 17 is the data-out (Dout) pin that sends a serial stream of pulses containing the address and data. It is connected to the data input pin of the TRX RF module.

The time-out control is set using input keys S1 through S4 to turn on/off the devices at predetermined time. The default time for all the devices is ‘00’ seconds. So using ‘up’ key you can increment time by one second, and using ‘down’ key you can decrement time by one second down. At the same time, the LCD module shows the current status of increments and decrements.

When the time-out for a device is set, press ‘ent’ key so that the program control transfers to the next device for time-out settings. In the same way, the remaining three time-out settings must be done before pressing ‘run’ key. When ‘run’ key is pressed, it executes the device control program subroutine in the microcontroller and the program automatically collects the time-out information entered by the user and sends the processed data to encoder IC HT12E. The encoder IC sends the data to Din (pin 2) of the RF transmitter module. The data is transmitted by the TRX-434 module to the receiver section through the antenna.

Receiver circuit. Fig. 5 shows the receiver circuit. The RF receiver (RX- 434) module can receive the signal transmitted by the transmitter from a distance of up to 9 metres (30 feet). The range can be increased up to 30 metres using a good antenna. 
fig5
Dout pin of RX-434 RF module is connected to Din pin of decoder IC HT12D (IC4). Din pin of IC4 receives address and data bits serially from the RF module. Decoder IC4 separates data and address from the received information. It accepts data only if the received address matches with the address assigned to encoder IC1 (HT12E). We have used ‘1111’ as the permanent address for communication. Pins 1 through 8 of IC4 are address pins and therefore 256 possible addresses are available. The address on the encoder and decoder ICs must match for the data to be valid.
The HT12D decoder receives serial addresses and data from the encoder that are transmitted by a carrier signal over RF medium. The decoder compares the serial input data three times. continuously with its local addresses. If no error or unmatched codes are found, the input data codes are decoded and transferred to the output pins. VT pin (valid transmission) goes high to indicate a valid transmission. The HT12D provides four latch-type data pins whose data remains unchanged until new data is received. 

Data pins D8 through D11 (pins 10 through 13) of the decoder send 4-bit data to CD4519 multiplexer IC5.
fig6
CD4519 multiplexer. This IC provides four multiplexing circuits with common select inputs (SA and SB); each circuit contains two inputs (An, Bn) and one output (On). It may be used ton select 4-bit information from one of the two sources.

There are eight input lines (A0 through A3 and B0 through B3), of which four (A0 through A3) are permanently connected to Vcc through resistor R19, while the rest four (B0 through B3) are connected to the data output lines of the decoder (IC4).

The select inputs can be connected to either Vcc or VT pin (pin 17) for latch or momentary mode-selection section. Jumper switch (Js) is used to select between latch and momentary operation. When latch mode is selected, data present at the output pins is latched, i.e., they remain the same and the respective relay energises until the next change is made in the mode selection. When momentary mode is selected, data present at the output pins is available as long as VT  pin remains active-high. As soon as VTpin becomes active-low, the respective relay de-energises.

The latched output data from multiplexer CD4519 is fed to relay driver IC ULN2003, to control up to four devices through the relays (RL1 through RL4). VT pin is connected to LED4 through IC6 to indicate the status of VT signal when it is active-high.

Software program


The software flowchart programmed in the microcontroller of the transmitter section is shown in Fig. 6. It is written in Assembly language and compiled using ASM51 software to generate the hex code. The hex program can be burnt into the AT89C51 microcontroller by using any standard programmer available in the market. We have used TopView programmer from Frontline Electronics to program the microcontroller.

The software program is designed to accept the input from the user as well as control the devices. It identifies the key pressed and displays the key code on the LCD module.

In the program, the LCD module is initialised first. As soon as the time-out is set, all the four devices turn on initially, then a particular device turns off at preset time. In this project, the timeout range is 00 to 99 seconds, which can be easily modified to extend the time duration in the delay subroutine of Assembly code.

Port 0 is configured as output port and interfaced with the RF module through encoder IC1. Port 1 is used for LCD interface and port 2 is used for the input from push-to-on switches.

Circuit operation

When the system is switched on, the startup message “press any key” appears on the LCD screen. When any key is pressed by the user, the LCD displays the message “to set time out press ent!”. Pressing ‘ent’ key displays the following messages on the LCD with a cursor blinking near the first device ‘D1_T’:

D1_T= D2_T=
D3_T= D4_T=

Use ‘up’ and ‘down’ keys to set the time for controlling the devices. The set time for each device on the LCD screen looks like this:

D1_T=10 D2_T=20
D3_T=30 D4_T=40

Now press ‘ent’ key followed by ‘run’ key. A device control subroutine executes and sends the data to the RF module, which transmits the data through ANT antenna. You can set maximum of 99 seconds as the control time for the device. If you set it to 00, a particular device is turned on for infinite time.