Page 1

EEWeb Issue 83

January 29, 2013

Nigel Toon CEO, XMOS


Homemade Tools - Part 4


Removable Embedded Component Using Standard SMD

Electrical Engineering Community



Nigel Toon


XMOS Interview with Nigel Toon - President and CEO

Featured Products


New Removable Embedded Component Concept Uses Standard SMD


BY RODNEY GREEN WITH MULPIN How to overcome the challenge in radio systems of keeping a receiver free from unwanted mixer products and internally generated signals.


Homemade Tools - Part 4 BY PAUL CLARKE WITH EBM-PAPST This final installment shows how to use a USB storage device to look at sample data from the homemade three-channel temperature logger.

Product Overview: Rigol DS-4162 Arbitrary Waveform Generator


RTZ - Return to Zero Comic






EEWeb | Electrical Engineering Community




XMOS is a privately held, fabless semiconductor company based in the UK. We spoke with Nigel Toon, the President and CEO, about its revolutionary multi-core microcontroller technology, what makes its technology particularly easy to use, and the direction the company is headed in over the next couple of years.



EEWeb PULSE Why don’t you give us a little background about XMOS as a company?

time capability into all the different applications.

The technology for XMOS came out of Bristol University here in the U.K. Although it was founded in 2005, the company was really funded, and really started getting going in 2007. The first products came out towards the end of 2009, so really the customer base has been ramping since early 2010.

From an architectural standpoint, how does your multi-core microcontroller differ from a typical microcontroller? Is it different because you have programmable logic inside it as well?

The products that the company has developed are really quite revolutionary and breakthrough technology. One of them is a new type of microcontroller, what we would call multi-core, which makes it sound very conventional. But actually, within that, the way that we build our multi-core products allows us to build a product that is very flexible, and allows us to program in the different interfaces that people might need, specific to their design, and also provide a solution that is much more responsive for I/O signals, has very low latency, and is really ideal for complex, real-time systems. What we really end up doing is making complex embedded systems much easier to design. We see this technology going into a broad number of applications, from consumer – we’ve been very successful in audio – but also expanding into a broad swathe of industrial applications. We are also starting to get design wins in automotive as well. We can really see that the way we’re going to build out the XMOS business is by expanding into a broad set of applications, really leveraging the flexibility we have in our products, and allowing people to get the benefits of the performance, and the responsiveness, and the real-


Well, yes. Not in the traditional FPGA sense, but we have some logic on the pins, so we can make some logic decisions based on inputs at the pins. But the key difference is in the architecture of our high-performance 32-bit RISC processor. One of the challenges when you build a high-speed processor is that you typically need to have a pipeline, to be able to run the processor at high speeds. What that then means is you need to serve that pipeline. You typically end up having a cache to be able to keep the instruction pipeline full, and to hide the memory latency for your design. What we have done is come up with a very different type of architecture. Rather than having the pipeline process the next instruction in your program sequence, what our pipeline does is time-slice between different processor cores or logical cores. So what you’re effectively able to do is to interleave on this high-performance processor. It’s low in terms of silicon area, low in terms of cost. We interleave these different logical cores together. Each instruction operates in one instruction cycle, so we don’t need a cache either.. What you end up with is a processor which is very fast-responding, and very deterministic. You can write your code, and from that you can know exactly how fast your code

EEWeb | Electrical Engineering Community

is going to execute. We add to that connections to the pins, so rather than there being interrupts, we bring the I/O pins through some logic that is available. You have these banks of logic that are available and you can connect through the pins to make logic decisions. For example, you can timestamp inputs coming in, precisely ‘clock’ data out, or you

“What we ha is come up w very differen architecture than having pipeline pro next instruct program seq what our pip is time-slice different pro cores or logi can look for a particular address occurring on a bus, and then stop to process the data. Or you can timestamp signals coming in, or take a high-speed serial stream and deserialize that, and going back the other way, serialize a parallel stream into a high-speed serial stream. So you can talk to the outside world in all the different ways that you need to, and process and control that

INTERVIEW directly from one of these logical processor cores. What we end up with is a processor that has, on a smallish device, 8 logical cores. Those cores can be used to do 32-bit compute, and they can do DSP processing. We can also use a processor to build any kind of peripheral interface, for example,

ave done with a nt type of e. Rather the ocess the tion in your quence, peline does between ocessor ical cores.” a USB or an Ethernet 10/100 Mb interface, or I2S. Whichever set of interfaces you need, we can program that in. What that allows us to do is, rather than having the conventional long SoC development cycles that run into years, and constantly struggling to support the next version of any particular standard, is we can very

quickly support new standards. For example, we support Ethernet AVB, which is just emerging. We support a range of audio interfaces that you wouldn’t conventionally find on a microcontroller. And we’re not bearing the burden of those being on the chip for every customer to pay for: they are provided as soft IP blocks, which the customer can choose to program into the chips. They can select the particular interface that they need for their particular design. You end up with a solution which is very, very flexible. How does it work with your soft IP? Are there licensing or payments? Is there a fee associated with the soft IP, or is it provided? How does that work? We want to make the technology very easy to use; we want to make it available to all customers, from the biggest customers through to the individual engineer, and so our software is free to download off the web. The software is very complete, it’s professional grade, it’s very comprehensive with some unique features, and it’s all available for customers to use. The same goes for the xSOFTip blocks that we have as well. We provide those free of charge. The library’s available, and we also provide all of the source code for those IP blocks as well. If a customer wants to modify one, well, you can take it, and you can modify it. If you want to create your own, you can look at how we built a similar interface, and you can modify, and create your own interface as well. We’ve got a community of people out there who are starting to do just that. And to support this we’re just announcing a new set of

development boards called sliceKIT. To mirror the concept here, we’ve developed a modular set of development boards. There’s a simple core board, that has an xCORE processor in it, and then {I/O cards called} slices that you can easily plug in to that core board to add different interface functions. If you want audio, you can plug that one in, if you want Ethernet you can plug in your Ethernet PHY. If you want memory you can plug in a SDRAM. You can plug in an LCD. In the same way you can program into the device specific interfaces you need, with our development system you can actually build up in hardware the whole system as well. Is the soft IP developed internally in the company then? Yes, we have a whole library of what we call xSOFTip that we have developed, and we’re continuing to add to that. What we try to do is provide a near-term roadmap of IP that we’re developing so customers can tell us, “Oh, hurry up with that one,” so that we can be responsive to what customers want. There are also, on the community side, some people who have developed IP that they’re making available in open source as well. Obviously the ones that come from us have typically gone through a very rigorous evaluation, especially when we are performing to a standard. We are buying test equipment and conforming to all of the industry standards. Some of these other interfaces provide functionality, but might not necessarily validate things like that they are fully conformant to a standard. However, they are available for customers to go and use as well, and it adds to the capabilities that are available. Visit


EEWeb PULSE How about development tools? Early on you mentioned some professional development tools that are free. Can you elaborate on some of your development tools that are available for designers? We’ve put a lot of effort into this. Certainly over the last 6 months we’ve focused a huge amount on improving, making the tools easy to use, and making sure that the results that you get, such as code size and runtime performance, are absolutely the best in class. We’re calling this new release of

Having created a user design, we’ve also, and this is very unique in terms of software development environments, we’ve got a static timing analyzer. You can actually look at your design, and ask, “from this input occurring how quickly does my control loop respond?” and you can see that happen really quickly, and deterministically, on the xCORE processor. We’ve also got cycle-accurate simulators as well. This allows you to actually look at the simulation for your design, and see the software controlling the real systems.

package. For the debugger, there is a debug adapter which actually we build using one of our own chips at a very low cost – about ten bucks off of the Digikey website. Is XMOS a fabless company? Yes, we’re a fabless company. We build in 65 nanometers through TSMC, so more advanced process technology than you’re used to seeing other microcontroller companies using. This allows us to really get the performance that is possible with our chips, and also to keep the size and the cost very very low.

“The whole point of the company is to build out and expand the customer base – to get more and more people using the technology and build a very broad customer base for our technology.” the tools xTIMEcomposer. They’re available off our new website that we’ve just launched. What you have in there is an Eclipse, industry standard GUI Development environment, and LLVM compilers for C and C++. We’ve actually got some extensions in these that allow you to really control timing and the multicore aspects of the designs. You can easily describe multiple tasks you are trying to run in different cores or parallel code that you want to run in parallel or on different cores. There’s some simple extensions you can use in C to achieve that.


We have some debug capabilities that allow you to get into, for instance, a logic analyzer, and look at what’s happening on the pins as well as what’s happening inside the devices, unobtrusivley. This really makes designing, debugging, and developing these complex real-time systems much, much simpler. And all of the features, your timing analyzer and the ability to debug with this logic analyzer, those all come as part of the software package? They’re all part of the software

EEWeb | Electrical Engineering Community

We’re a private company; we’re funded by venture capital and we’ve had about $40 million in investments in the company so far. We’re very well funded, with tier-1 VCs supporting us. The whole point of the company is to build out and expand the customer base – to get more and more people using the technology and build a very broad customer base for our technology. We’re based here in Bristol, in the U.K., which is where I’m sitting today, but we’ve also started to expand and build a facility in Chennai, in India, as well.

INTERVIEW We’ve just hired somebody to lead that group, and we’ve got about 10 people on the ground there. That’s going to help us to really expand and get more of these xSOFTip blocks out and available for customers, and expand the range of interfaces that are available in our chips. How many people work at XMOS? The company is still pretty small, which is part of our plan, to keep our cost base quite low. That is kind of the new style of building chip companies --- you need to keep your cost base low. We’re about 50 people. We’re continuing to grow and expand, we’re adding people, like I said, in India, but also here in Bristol as well. The whole idea is to have really bright, capable people developing great products, but to keep our size small so we all work together as a tight team. The low cost base will help us to get to that magical break-even point and the high-growth phase, which we think we can do pretty quickly. Are there particular segments of the market that you foresee being able to capture more easily than others? Are there certain parts that you are targeting? Oh definitely. For us to come out and claim that we can win every microcontroller socket—I think that would be a pretty difficult thing to do, and it’s really not where we are. There is a huge number of very capable products out there that are low cost and low power. Typically where you’re going to be using an an xCORE product is when you need something that responds faster {or more predictably}. We see a lot of designs where a customer has a microcontroller

sitting right next to an FPGA, and we can soak that up into one chip. We also see, quite often, where you have a microcontroller and then you need a DSP or some other more high-performance processor to do some signal-processing or something. Again, you can soak that up into one chip. And so it’s really when you need more performance, when you need a microcontroller to respond faster, if you’re confined on a current microcontroller – these are the times when xCORE is going to be the processor that you ought to try and use. We are not trying to win the whole market. We see ourselves very much at the high-performance, real-time end. We’re positioning our product at the high-end of the market in terms of the performance and response time. Real-time performance, low-latency, that’s very much where we play. We’re going to go into the more complex systems, and our goal is to make designing those systems much easier.

your standard microcontroller. We can be programmed and used in the simple way you use a normal microcontroller, but at the same time give you a performance and a responsiveness that you previously only really found if you sat down and designed dedicated hardware or programmable hardware. That performance envelope is what really makes us stand out as being very different and having very unique technology that is going to have a very broad set of applications. We’re already seeing them.

To find out more information about XMOS, visit:

Are there any areas or topics that we haven’t discussed that you would like to touch on? One of the key things, just in terms of where we are different, and where we stand out, is this realtime capability. People talk about real-time in terms of a millisecond response. In fact, that would be fast for your standard microcontroller, whereas we’re in the nanosecond range in terms of how quickly we can respond. Typically we can respond on events in 100 nanoseconds. Even as you get more events happening asynchronously, we can actually handle those with our multi-core, as well as when you need multiple channels. These are all areas where we really stand out as being much more capable than Visit


Technology You Can Trust

Take the Risk out of High Voltage Failure with Certified Avago Optocouplers IEC 60747-5-5 Certified

Optocouplers are the only isolation devices that meet or exceed the IEC 60747-5-5 International Safety Standard for insulation and isolation. Stringent evaluation

tests show Avago’s optocouplers deliver outstanding performance on essential safety and deliver exceptional High Voltage protection for your equipment. Alternative isolation technologies such as ADI’s magnetic or TI’s capacitive isolators do not deliver anywhere near the high voltage insulation protection or noise isolation capabilities that optocouplers deliver. For more details on this subject, read our white paper at:

FEATURED PRODUCTS 150 Mbit Fiber Optic Transmitter MOST150 transmitter and receiver are designed to transmit/ receive up to 150 MBit/s optical data which are DCA coded. Both are packaged in 7-pin transfer molded, low-cost packages ready for assembly into MOST® plastic fiber optic connector receptacles. The transmitter utilizes a 650 nm LED source with integrated optics for efficient coupling into 1mm Polymer Optical Fiber (POF), and the receiver contains a high speed PIN diode to receive this light. These optical components are specified for operation over a -40°C to +95°C temperature range, and meet the reliability requirements of automotive applications. For more information, please click here.

High Voltage Surge Withstanding Resistors Vishay Intertechnology, Inc. introduced a new series of axial cemented wirewound resistors that are the industry’s first to offer a customized high-voltage surge withstanding capability up to 12 kV. Designed to limit in-rush currents during high voltage surges, the Vishay Draloric devices are optimized for power supplies in electronic meters, industrial and home appliances, and electronic ballasts. For increased safety in overload conditions, the devices feature non-flammable cement coatings and high-grade ceramic cores. The Z300-C series features a high-voltage surge withstand capability up to 12 kV as per IEC 61000-4-5 (1.2 μs/50 μs). For more information, please click here.

Low Profile 600W TVS Diode Littelfuse, Inc. has introduced the TPSMA6L Series of Transient Voltage Suppression (TVS) Diodes. This new series can provide secondary transient voltage protection from transients induced by load dump and other transient voltage events for automotive electronic control units, sensors, entertainment systems, and other applications that require high reliability. This SMA device’s low profile DO-221AC package is less than 1.1 mm high, but it offers the same peak pulse power dissipation (PPPM) rating (600W) as standard SMB devices. For more information, please click here.

Single Box Arbitrary Waveform Support Agilent Technologies Inc. announced support for the High-Definition Multimedia Interface (HDMI) and Mobile High-Definition Link (MHL) sink tests through its M8190A arbitrary waveform generator and enhanced N5990A test-automation software. The Agilent solution gives engineers a new way to conduct sink testing and provides a costeffective and compact alternative to Agilent’s well-established E4887A HDMI TMDS signal generator platform. The new test solution reduces development costs while providing accurate test results with greater flexibility than other HDMI and MHL test solutions. For more information, please click here.





Removab Embedded Component Concept uses Standard SMD Techniques in Manufacture Rodney Green Mulpin Assembly Technology


EEWeb | Electrical Engineering Community


ble The Challenge As a designer of High Frequency Radio equipment for over 40 years, I found difficulties in sufficiently isolating one stage of a radio system from another can cause interference between adjacent and other nearby circuits on a PCB, thus reducing the effectiveness of the communication system. The push towards higher Dynamic Range (D.R.) in radio receivers has meant higher power requirements in local oscillators which in many cases also need to be square waves that contain harmonics well into the UHF region. This, in turn, has meant even greater challenges in keeping the receivers free from unwanted mixer products or even internally generated signals being received in the antenna circuit of the receiver.



EEWeb PULSE The Search For a Solution The abovementioned scenario led me to the idea that components could be embedded through a round opening within the Printed Circuit Board or PCB. If each layer of the PCB had a different sized hole, decreasing in size on each layer down from the top of the PCB, a component could be inserted down through the top of the PCB, leaving access to each layer of pins on a component for soldering. See Figure 6. Once the components are assembled into a PCB, a metal screening lid for each component could then be attached to the top layer of the PCB with a second pass through the soldering process (if this were required). This concept needed a name, which I called Mulpin, short for “Multilayer Pins.” There seemed to be two additional advantages to fitting the metal screening lid, one being improved heat removal from the component. If the component is an integrated power amplifier, for instance, as shown in Figure 7, the top surface of the component can lie just below or level with the top surface of the PCB. This enables a small amount of heat sink compound to be placed on top of the component before the metal screening cover is soldered in place. The top surface of the PCB assists in the removal of excess heat from the component. If the top of the integrated power amplifier is made of metal, the solder would add to the rigidity of the component, as no heat sink compound would be required and the top of the component could be soldered to the top of the PCB. Secondly, if the metal screening lids are all of the same thickness, a single standard extruded heat sink could remove all of the heat generated by all components on a PCB. It might even be possible to not use the metal screening lids at all on such a PCB, and just use the heat sink alone. This would have the added advantage allowing static measurement when fault-finding; changing any of the components would be simpler.

Prototype Testing: Practical ”Mulpin” Components? With the absence of Mulpin concept embedded components, it was decided to “Mulpinise” and embed a standard CMOS quad NAND gate connected up as two oscillators, one at an audio frequency of 2 kHz, which modulated another at a higher frequency of approximately 1400 kHz in the AM broadcast band. This combination ensured that harmonics of the oscillators extended to beyond 100 MHZ.


On the same PCB I also embed a 100 mA 5 volt linear regulator. The reasons for this will become clear later in this article.

Figure 1: Text Box showing both PCBs in position A second standard SMD BOARD, shown uppermost in Figure 1, and identical in layout was also built. The PCB for “Mulpinising” needed to have a rectangular hole for embedding each of the integrated circuits to match the shape of the components. Rectangular holes are much more expensive to fabricate in a PCB than round ones but that was the state of play. The top layer also had the same size hole, and a metal screening plate was made up for each of the I.Cs. These plates were left off the PCB until part way through testing, as it was desired to know the contribution to the RFI/ EMI by these components. The passive components were mounted beneath the PCB and connected by vias to the integrated circuits on the mid layer of the PCB. There was no cover placed over the passive components until part way through the testing so that the contribution to the RFI /EMI of these components could also be determined. See below for details. The reference PCB for all of the testing was the SMD board. The improvement in RFI performance of the “Mulpinised” PCB was in direct comparison to this.

Testing and Test Equipment Used Initially, to allow non-technical personnel to compare the improvement made to RFI from the “Mulpinised” PCB compared to the standard SMD board, a normal AM broadcast receiver was used to listen to the signals from the two PCBs. The Mulpin PCB was silent but the SMD BOARD was somewhat noisy. However this was not sufficient to quantify the improvement. The test equipment consisted of an electric field probe shown in Figure 2, which contained a small sampling antenna mounted on its PCB. The antenna connected to

EEWeb | Electrical Engineering Community


analyser was set such that the side bands close to the carrier on 1.4 MHz could be seen as shown in Figure 4. The electric field probe tuning control was adjusted for a peaked response. And a marker set to that level. The reference SMD board was then switched off.

Figure 2: Electric Field Probe the top end of a tuned circuit, which in turn connected the gate of an RF amplifier, MOSFET. The amplifier output is terminated in a 9:1 impedance matching transformer to allow connection to a 50 Ohm spectrum analyser. The tuned circuit minimally loaded the antenna at the received frequency, which allowed even small electric fields to be displayed. A spectrum Analyser was used. In this case it was an Agilent E4411B with a 100Hz filter option fitted.

Testing Prior to assembling both the SMD and Mulpin PCBs onto the test box as shown in Figure 1, two SMD BOARDs were fitted and the Electric field probe was used to check the emissions from both PCBs, one at a time to ensure both were being received equally by the electric field probe. The two signals were within 1 dB of each other, which was more than adequate for the ensuing tests. The standard SMD BOARD and the Mulpin PCB were then mounted alongside one another as shown in Figure 1. The electric Field probe was then mounted on grounded metal stand offs equidistant above both of the PCBs as shown in Figure 3.

Figure 3: Electric field probe mounted in position The reference SMD BOARD was tested by turning the power on to that PCB only. The spectrum analyser was set to view the signal at 1.4 MHz. The span of the

Figure 4: SMD reference PCB Power was then applied to the Mulpin Concept board, and a short piece of wire (croc clip) was attached temporarily to the output connector of the Mulpin Concept PCB. This was simply to verify that the PCB was working and a display similar to that of Figure 4 could be seen. The croc clip was removed and the spectrum display was as shown in Figure 5. This represents that amount the RFI was reduced in the Mulpin Concept board when compared to the SMD board. The reduction was 86dB or better (four hundred million times). When the power was removed from the PCB, there was no discernible difference on the spectrum analyser reading. Other intermediate tests were also done, and the initially the prototype Mulpin test board was completely screened while the conventional PCB was not screened at all, with the exception of its output pins. It would be good to know what the difference is when non Mulpin integrated circuits are used, and for that matter how much of the radiated emission is caused by the small static parts beneath the PCB. Whilst assembling other prototypes, tests were carried out at intermediate stages to facilitate these test results. These test cannot be duplicated with the fully Mulpin PCB, it is none the less interesting to see the test results. EMI/RFI suppression occurs when the integrated Visit




circuits are a standard SMD. All other components are screened. :- 40dB below the SMD board. EMI/RFI suppression when only the components under the PCB are not screened. Integrated circuits are screened:- 51dB below the SMD board.

fed from a 26 volt supply. The regulator dissipation was 1.81 Watts. The voltage regulator on the non Mulpin PCB commenced to close down due to its inbuilt temperature protection circuit, before 15 minutes but typically within 1 minute. (See tables 1 and 2 on page 17).

Removable Embedded omponent From the above it can be seen that the ultimate RFI suppression is not achieved unless all of the components are embedded.

The same test on the Mulpin PCB resulted in no shut down after eight hours, after which time the test was concluded. (See tables 1 and 2 on page 17).

What Do Mulpin Components Look Like?

Mulpin components are expected to have many forms and a few of these are shown below. Figure 6 shows what is likely to become one of the classic and instantly recognizable Mulpin Packages which has two layers of pins. This package has the ability to be connected directly to the heat dissipation (top or bottom or even both) layers of the PCB. The top (square) cover is likely to be supplied as a separate part along with the I.C. although this is not an absolute requirement.

Concept uses Standard SMD Techniques in Manufacture Figure 5: Mulpin PCB referenced to that of SMD board

Thermal Testing

This test put the maximum load on the voltage regulator. This was done by connecting an additional load resistor to the Voltage Regulator. In this test it was necessary to increase the supply voltage to the Test Box from 12 Volts to 26 Volts. This increased the power dissipation in the Voltage Regulator due to its high load and the increased supply Voltage, to the point that its temperature rose, causing it to close down due to its inbuilt temperature protection, on the standard SMD. The Voltage Regulator, however, kept working on the Mulpin Board. What happened was that the Mulpin top plate heat sink on the voltage regulator dissipated, increasing heat away from it and into the large area of the PCB ground plane. (Top foil of the PCB). Note that to do this, there was very little increase in the area (foot print) taken up by the circuit, but its heat dissipation has markedly increased.

Figure 6: Two views of a multi-layer active component (Integrated Circuit) before placing into the PCB. Note that in this example the PCB opening for the component is complementary in shape to that of the connections of the integrated circuit. This integrated circuit takes 1/3 of the footprint of an equivalent current SMD component.

Figure 7 is particularly interesting as it has been scaled against a standard miniature MSOP8 package.

Additional information available on

The following test results on the Mulpin & Non-Mulpin PCB were conducted over an 8 hour period

Abridged Test Results Thermal test. The voltage regulator (100mA 5V type) was loaded to its maximum output current whilst being


EEWeb | Electrical Engineering Community






















A B C D E F, F’ A’ N

Millimeter Min.


2.90 4.75 2.90 0.78

3.10 5.05 1.10 3.10 0.94

0.95 TYP 1.9 TYP Heat Sink Plate


G H, H’ J, J’ K L G M

Millimeter Min.


0.40 0.22

0.70 0.38 0.65 TYP 0.15 0.23

0.05 0.08 0.65 TYP 0.5 TYP

Figure 7: Shows a possible Mulpin IC to scale against a MSOP8 package. Note that the Mulpin Concept component is about 1/2 the size, and has a direct connection to the top ground plane PCB layer.

Figure 8: Temperature testing with probe directly over center of the voltage regulator

Figure 9: Temperature testing with probe directly over the center of the PCB



Transform Your iPhone, iPad or iPod into an Oscilloscope with the iMSO-104 Begin Your Experience Now

Experience the iMSO-104 as Joe Wolin, co-founder of EEWeb, gives you an in-depth look into the future of oscilloscopes. UBM ELECTRONICS



Breathe new life into medical product interfaces

NXP’s proven interface products enable medical and health system designers to add features with minimal modifications. Within our portfolio you’ll find LCD displays and capacitive touch interfaces, system connectivity bridges & UARTs, LED controllers, real-time clocks, and I2C-bus peripherals & enablers. To learn more, visit


Homemade Tools Part 4 Over the last few articles, I have been showing how you can make your own homemade tools, and demonstrating my progress towards making a three-channel temperature logger using the mbed development board. This article closes the series by looking at USB storage and some sample data I have recorded.


EEWeb | Electrical Engineering Community


Paul Clarke Electronics Design Engineer




Software-wise this is also just as easy to add to your code. The pre-built libraries means you only have to include the MSCFileSystem. Then, as shown in my past articles, you only have to open and write to the file as before.

MSCFileSystem msc (“USB_dive”); FILE *fp = fopen(“/USB_drive/ logfile.csv”); fprintf(fp, “something to write to USB\n”); fclose(fp);

First of all, I want to look at one of the big advantages of using kit parts. I totaled up the price of the boards, connectors and a waterproof box I bought in order to make a data logger, it came to around $100. Looking on the big distribution sites for a datalogger that would perform the same function, I found them to be two or three times the cost of mine. Not only was mine cheaper, but it does exactly what I want it to do! For a datalogger to have lots of storage you need some form of flash memory. For example, the USB flash memory that is available to store data is only 2MB on the mbed. This is not going to store a lot of data. However, the mbed has a USB host interface allowing other USB devices to be plugged in. A 2Gb USB flash pen drive can be connected with only a USB connector. The fact that no extra parts are needed makes this a very low cost add-on.

You can store a massive amount of data on a USB drive. For example, I updated the dataloggers code to record samples once per minute. Over a 24-hour period, this generated a 30k file. If you need to log data quickly or over long periods, you can see that you can extend your data logging capabilities a lot with your own tool. At first, my results (on the graph on page 23) look a little odd. Starting around mid day the graph shows the following: The data logger was placed at a window in a south facing bedroom with the Green sensor outside. The Blue sensor shows the room temperature and the Red like the temperature of a radiator. It’s easy to see when the heating kicks in, and how, when it’s colder, the radiator runs a lot hotter. There is even a period at 1300 mins that I opened the window and the room temperature dipped causing the radiator to respond with a much larger spike as it tried to recover the room temperature. With my homemade temperature logger, I was able to adapt a tool to my needs and situation.

About the Author Paul Clarke is a Digital Electronics Engineer with strong software skills in assembly and C for embedded systems. At ebm-papst, he is developing embedded electronics for thermal management control solutions for the air movement industry. These controllers monitor environmental inputs like Temperature, Humidity and Pressure and then control the speed of their fans based on various profiles. Their controls also interface with


EEWeb | Electrical Engineering Community


other systems over RS232/485 or TCP/IP as well as a host of other user or control interfaces. As an engineer, he is responsible for the entire development cycle, from working with customers on requirement specifications though to circuit and PCB design, developing the software, release of drawings and supporting our production. In the past he has worked in range of industries developing scientific equipment, retail weighing systems, street lighting ballasts, motor sport. A full list of his job roles can be found on LinkedIn – More recently, he has become more actively involved in writing blog posts for engineering sites like DesignSpark, EngineerBlogs and here on EEWeb.

To view previous parts of the series, click on the images to the right.



C eb om .c m om un ity

W eb Ele ct ric al En w gi w ne w er .e in ew g

EE Making Wireless Truly Wireless: Need For Universal Wireless Power Solution

Dave Baarman Director Of Advanced Technologies

"Sed ut perspiciatis unde omnis iste natus error sit voluptatem accusantium laudantium,

doloremque totam



eaque ipsa quae ab illo inventore veritatis et quasi architecto beatae vitae


dicta sunt explicabo. Nemo enim ipsam voluptatem quia voluptas sit aspernatur aut odit aut fugit, sed quia consequuntur magni dolores eos qui ratione voluptatem sequi nesciunt. Neque porro quisquam est, qui dolorem ipsum quia dolor sit amet, consectetur, adipisci velit, sed quia non numquam eius modi tempora incidunt ut labore et dolore magnam aliquam quaerat voluptatem. Ut enim ad minima veniam, quis nostrum exercitationem ullam corporis suscipit laboriosam, nisi ut aliquid ex ea commodi consequatur? Quis autem vel eum iure reprehenderit qui in ea voluptate velit esse quam nihil





Online Circuit Simulator PartSim includes a full SPICE simulation engine, web-based schematic capture tool, and a graphical waveform viewer.

Some Features include: • Simulate in a standard Web Browser • AC/DC and Transient Simulations • Schematic Editor • WaveForm Viewer • Easily Share Simulations

Try-it Now!


Overview of the

RIGOL DG-4162 Arbitrary Waveform Generator EEWeb Tech Lab

Layout One thing you’ll notice about the DG-4162 is that the screen is nice and large, compared to the size of the instrument. The waveform functions, located at the top right of the instrument, are all easy to find and easy to set. The buttons are backlit, which allows you to quickly tell which function you are using. To set up your channel, all your buttons are right on the front of instrument, to the bottom right of the display screen. When you’re actively using Ch 1 or Ch 2, the respective channel button will also be backlit. If you turn the output


on, that will also light up. The buttons are independent to their channels, and are color-coded to their output and syncs, which are located along the bottom of the generator. The independent buttons make it quick and easy to set your settings; it is much easier to use them than through channels on soft keys. The generator also has a keypad, so that you can key in your settings quickly and easily, rather than dialing the settings in with a knob. If you prefer, you can dial in the settings, but you may find that using the keypad is quicker.

EEWeb | Electrical Engineering Community

Independent Channel Buttons

Let’s say that you want to configure Ch 1 to be a square wave. Select channel one, and check to see if the button is lit. Then, under the “Waveform” menu, select the square wave button, and set it using the keypad on the far right of the generator and the grey softkeys to the right of the display screen. In the video example, it is set to 5Mhz. If you want to change the amplitude, press the grey “Amplitude” soft key, to the right of the display screen, and change that to, for instance 3v, peak to peak. You’ll notice that when you click the square wave button, the display is changed to show a square wave.


One nice thing about the generator is that you also have modulation. If you set the wave back to a sine wave, using the “Waveform” menu, you’ll notice that the image changes from a square wave to a sine wave. Turn on some modulation, using the “Local” menu right below the “Waveform” menu, and you’ll see that, based on the default settings, a modulated waveform is already displayed. This default display is very helpful, especially if you’re using something like a harmonic waveform. To display a harmonic waveform, turn of modulation by once again pressing the “Mod” button under the local menu. Then press the “Harmonic” button under the waveform menu, and wait briefly for the image of the waveform to generate. To start, you’ll see that it gives you a second order, using only harmonics. To add some harmonics to that, click the bottom gray “Order” soft key, and use the key pad and soft keys to go to the 6th order. The image should regenerate again, and then you’ll be able to see the waveform that it is actually putting out. It also displays the amplitude of the fundamental relative to each harmonic. By using the grey soft keys, you can add Odds. Go to “All,” and then you will see all the first five harmonics, because you’re at a 6th order signal. You will see the actual signal that’s being put out by the waveform generator.

Two Channels

Another nice thing about the generator is that it has two channels which are linked. For instance, if you set Ch 1 back to a sine wave, what you can do is offset Ch 2 in Phase. Use the keypad to offset it by 90 degrees, and you’ll essentially have a sine and a cosine function.


like, you can save your state using the “Store” button. The one issue that may be a problem with this instrument is that it is rather time-consuming to save a state because the instrument doesn’t give you a default file name. You will need to dial through the entire alphabet and decide on a file name. Once the state is saved, you’re ready to go and can recall that state any time, but it would be nice to see a default file name to make the process a little easier and more meaningful.

Conclusion The DG-4162 Arbitrary Waveform Generator is easy to use and offers great specs at a budget price.

Features and Price - 2 Channel - 160MHz Bandwidth Generator - Connectivity: LXI, USB - MSRP $1295.00

To watch this review and others from EEWeb Tech Lab:

Click Here

The Store Button Once you have you waveform configured the way you Visit


Charging Caps - Part 1

Payback - Part 2

Light or Dark Meat?

EEWeb Pulse - Issue 83  

Interview with Nigel Toon - CEO of XMOS; New Removable Embedded Component Concept Uses Standard SMD; Homemade Tools - Part 4; Product Overvi...

Read more
Read more
Similar to
Popular now
Just for you