<div class="entry-content">
    <div class="jetpack-video-wrapper"><span class="embed-youtube" style="text-align:center; display: block;"><iframe src="https://www.youtube.com/embed/fFI33f4TejM" class="youtube-player" width="740" height="416.418" frameborder="0" allowfullscreen></iframe></span>
    </div>
    <div class="blog-content">
Ken Burns has published 7 hardware projects on Kickstarter. He explains how it works.
    </div>
    
    <div class="blog-content-links">
        <div>
            Links:
        </div>
        <ul class="links-list">
            <li class="links-list-item"><a href="https://tinycircuits.com/">Ken's company TinyCircuits</a></li>
            <li class="links-list-item"><a href="https://fedevel.com/courses">FEDEVEL Online courses</a></li>
        </ul>
    </div>  
</div>

Can You Make Money on Kickstarter HW Projects?

<div class="entry-content">
    <div class="jetpack-video-wrapper"><span class="embed-youtube" style="text-align:center; display: block;"><iframe src="https://www.youtube.com/embed/2oA4X3OTz0M" class="youtube-player" width="740" height="416.418" frameborder="0" allowfullscreen></iframe></span>
    </div>
    <div class="blog-content">
Interesting experiments and examples to help you to understand ground layout in PCB. Explained by Hans Rosenberg
    </div>


    <div class="blog-content-chapters">
        <div>
            Chapters:
        </div>
        <ul class="chapters-list">
            <li class="chapters-list-item"><span class="chapters-time">00:00</span><span class="chapters-text">What is this video about</span></li>
            <li class="chapters-list-item"><span class="chapters-time">00:19</span><span class="chapters-text">Currents flow under track</span></li>
            <li class="chapters-list-item"><span class="chapters-time">03:10</span><span class="chapters-text">What happen when you are making a board</span></li>
            <li class="chapters-list-item"><span class="chapters-time">08:37</span><span class="chapters-text">Where currents flow</span></li>
            <li class="chapters-list-item"><span class="chapters-time">14:01</span><span class="chapters-text">Experiment: Cut under track</span></li>
            <li class="chapters-list-item"><span class="chapters-time">19:51</span><span class="chapters-text">Floating copper fill</span></li>
            <li class="chapters-list-item"><span class="chapters-time">23:15</span><span class="chapters-text">Grounded copper fill</span></li>
            <li class="chapters-list-item"><span class="chapters-time">27:04</span><span class="chapters-text">Experiment: Filter</span></li>
            <li class="chapters-list-item"><span class="chapters-time">35:05</span><span class="chapters-text">2 Layer vs. 4 Layer</span></li>
            <li class="chapters-list-item"><span class="chapters-time">44:00</span><span class="chapters-text">3 rules to prevent ground problems</span></li>
            <li class="chapters-list-item"><span class="chapters-time">46:05</span><span class="chapters-text">Example: Ground plane</span></li>
            <li class="chapters-list-item"><span class="chapters-time">49:52</span><span class="chapters-text">Example: 1 VIA per GND pin</span></li>
            <li class="chapters-list-item"><span class="chapters-time">54:46</span><span class="chapters-text">Example: Gap in GND plane</span></li>
            <li class="chapters-list-item"><span class="chapters-time">1:02:00</span><span class="chapters-text">Example: FPGA board redesign</span></li>
            <li class="chapters-list-item"><span class="chapters-time">1:05:16</span><span class="chapters-text">Star grounding</span></li>
            <li class="chapters-list-item"><span class="chapters-time">1:07:39</span><span class="chapters-text">Multiple ground planes</span></li>
            <li class="chapters-list-item"><span class="chapters-time">1:14:30</span><span class="chapters-text">Example: Digital and Analog on one board</span></li>
            <li class="chapters-list-item"><span class="chapters-time">1:16:40</span><span class="chapters-text">About Hans</span></li>
    </div>
    
    <div class="blog-content-links">
        <div>
            Links:
        </div>
        <ul class="links-list">
            <li class="links-list-item"><a href="https://www.youtube.com/@HansRosenberg74">Hans´ YouTube</a></li>
            <li class="links-list-item"><a href="https://www.hans-rosenberg.com/">Hans´ website</a></li>
            <li class="links-list-item"><a href="https://fedevel.com/courses">FEDEVEL Online courses</a></li>
        </ul>
    </div>  
</div>

Examples of BAD Ground in PCB Layout And How to Fix It

<div class="entry-content">
    <div class="jetpack-video-wrapper"><span class="embed-youtube" style="text-align:center; display: block;"><iframe src="https://www.youtube.com/embed/X-qubBLJDD8" class="youtube-player" width="740" height="416.418" frameborder="0" allowfullscreen></iframe></span>
    </div>
    <div class="blog-content">
What will happen if you don't have enough GND pins on your connector?
    </div>
    
    <div class="blog-content-links">
        <div>
            Links:
        </div>
        <ul class="links-list">
            <li class="links-list-item"><a href="https://www.colorado.edu/faculty/bogatin/">About Eric</a></li>
            <li class="links-list-item"><a href="https://fedevel.com/courses">FEDEVEL Online courses</a></li>
        </ul>
    </div>  
</div>

Do You Design Connector Pinout Correctly? | Eric Bogatin

<div class="entry-content">
    <div class="blog-content-img-wrapper">
        <img src="https://assets.fedevel.com/blog/2019/10/ac6c6-running-memory-tests.jpg" alt="running memory tests" />
    </div>
    <div class="blog-content">
        Every hardware design engineer wants to be sure that the DDR3 memory interface is working correctly. Here are some real examples of DDR3 memory testing from our open source <a href="http://www.imx6rex.com/">iMX6 Rex project</a>.
    </div>
    <div class="blog-content">
        <h2 class="blog-content-heading">Which of the memory tests?</h2>
        There are a lot of memory tests available. For this project I used three:
        <ul class="content-list">
            <li class="content-list-item"><span class="content-text">the standard ubuntu <a href="http://manpages.ubuntu.com/manpages/hardy/man8/memtester.8.html">memtester</a></span></li>
            <li class="content-list-item"><span class="content-text"><a href="https://code.google.com/p/stressapptest/">stressapptest</a> (according to the website “… It has been used at Google for some time …”)</span></li>
            <li class="content-list-item"><span class="content-text">the Freescale memory test included in the <a href="https://community.freescale.com/docs/DOC-96412">i.MX6 DDR Stress Test Tool</a> (the same tool which is used also for calibration)</span></li>
        </ul><br>
        I recommend the stressapptest.
    </div>
    
    <div class="blog-content">
        <h2 class="blog-content-heading">What did I test?</h2>
        I was curious, so I have done tests of “uncalibrated” and “calibrated” board. “Uncalibrated” board was using the unchanged settings of DDR3 memory registers (the same values as used on the reference board), “calibrated” board was using the proper register values which I have got after the DDR3 calibration.
    </div>

    <div class="blog-content">
        <h2 class="blog-content-heading">The results</h2>
        Initially, I was running the “uncalibrated” board. The <b>memtester</b> software was running on this board for a week with <b>no errors.</b> When I used the <b>stressapptest</b> – the board always <b>failed within one hour</b>. This is how the failing looked: <br><br>

        <i>“Uncalibrated DDR3” – Examples of failing memory test</i>
    </div>
    <div class="blog-content-code">
        <code>Log: Seconds remaining: 4350<br>
        Report Error: miscompare : DIMM Unknown : 1 : 1658s<br>
        Hardware Error: miscompare on CPU 0(0xF) at 0x2be72978(0x4ca1997a:DIMM Unknown): read:0xff7fffffffffffff, reread:0xff7fffffffffffff expected:0xff7fffffff7fffff<br><br>
        
        Log: Seconds remaining: 4840<br>
        Report Error: miscompare : DIMM Unknown : 1 : 1169s<br>
        Hardware Error: miscompare on CPU 0(0xF) at 0x2bd89a78(0x4e3c7a7a:DIMM Unknown): read:0xff7fffffffffffff, reread:0xff7fffffffffffff expected:0xff7fffffff7fffff<br><br>
          
        Log: Seconds remaining: 3100<br>
        Report Error: miscompare : DIMM Unknown : 1 : 2904s<br>
        Hardware Error: miscompare on CPU 0(0xF) at 0x38171e78(0x27dcbe7a:DIMM Unknown): read:0xff7fffffffffffff, reread:0xff7fffffffffffff expected:0xff7fffffff7fffff<br><br>
        
        Log: Seconds remaining: 5550<br>
        Report Error: miscompare : DIMM Unknown : 1 : 455s<br>
        Hardware Error: miscompare on CPU 0(0xF) at 0x2fced578(0x200f157a:DIMM Unknown): read:0xff7fffffffffffff, reread:0xff7fffffffffffff expected:0xff7fffffff7fffff</code>
    </div> 
    <div class="blog-content-text">
        After applying the correct DDR3 settings from the DDR3 calibration (adding the correct register settings into uBoot), the same board was running perfectly.<br><br>

        <i>“Calibrated DDR3” – running perfectly over night (the same board was failing before)</i>
    </div>
    <div class="blog-content-code">
        <code>Stats: Found 0 hardware incidents<br>
        Stats: Completed: 32146856.00M in 0.00s infMB/s, with 0 hardware incidents, 0 errors<br>
        Stats: Memory Copy: 32146856.00M at -24559.40MB/s<br>
        Stats: File Copy: 0.00M at 0.00MB/s<br>
        Stats: Net Copy: 0.00M at 0.00MB/s<br>
        Stats: Data Check: 0.00M at 0.00MB/s<br>
        Stats: Invert Data: 0.00M at 0.00MB/s<br> Stats: Disk: 0.00M at 0.00MB/s<br><br>
        
        Status: PASS - please verify no corrected errors</code>
    </div> 
    <div class="blog-content-text">
        Here is the command line I used for the basic testing:
    </div>
    <div class="blog-content-code">
        <code># stressapptest -s 3600 -M 256 -m 4 -C 4 -W</code>
    </div> 
    <div class="blog-content-text">
        If you would like to install the strassapptest on your own ARM board, <a href="http://www.imx6rex.com/software/stress-testing-stressapptest/">check out here.</a>
    </div>

    <div class="blog-content">
        <h2 class="blog-content-heading">Be aware</h2>
        Be aware, that you need to test more boards. I have tested couple of “uncalibrated” boards and not all of them failed the stressapptest. When you are happy with the results (all your boards must always pass the test), take couple of boards (at least 5) and run the same tests in an environmental chamber (from -40C up to the maximum temperature … 60/70/80C ..). All the “calibrated” boards must pass your testing.<br><br>

        Happy testing!
    </div>
    
    <div class="blog-content-links">
        <div>
            Links:
        </div>
        <ul class="links-list">
            <li class="links-list-item"><a href="http://www.imx6rex.com/">iMX6 Rex project</a></li>
            <li class="links-list-item"><a href="http://manpages.ubuntu.com/manpages/hardy/man8/memtester.8.html">Memtester</a></li>
            <li class="links-list-item"><a href="https://code.google.com/p/stressapptest/">Stressapptest</a></li>
            <li class="links-list-item"><a href="https://community.freescale.com/docs/DOC-96412">i.MX6 DDR Stress Test Tool</a></li>
            <li class="links-list-item"><a href="http://www.imx6rex.com/software/stress-testing-stressapptest/">iMX6 Rex - Stress tests</a></li>
        </ul>
    </div>
</div>


ARM DDR3 Memory testing

<div class="entry-content">
    <div class="blog-content-img-wrapper">
        <img src="https://assets.fedevel.com/blog/2019/10/4bf6f-imx6-rex-infra-red-comparision-image.jpg" alt="iMX6 Rex Infra-red comparision image" />
    </div>
    <div class="blog-content">
        Here are some pictures of the same PCB, but running different software applications:
        <ul class="content-list">
            <li class="content-list-item"><span class="content-text">Notice the CPU temperature difference when nothing is running (49.9°C) and when a test is running (76.4) – compare the first and third picture.</span></li>
            <li class="content-list-item"><span class="content-text">Have a look at the picture in the middle. Memories become more visible when running a memory test.</span></li>
            <li class="content-list-item"><span class="content-text">See the huge difference in Ethernet temperature when Ethernet cable is connected (the middle picture, bottom right corner) and disconnected.</span></li>
            <li class="content-list-item"><span class="content-text">It’s interesting to see, how the whole PCB will warm up from a few hot components – the module PCB is much warmer than the Baseboard PCB (in background).</span></li>
        </ul>
    </div>

    <div class="blog-content-text">
        <i>Picture: Uboot only (Ethernet unplugged).</i>
    </div>
    <div class="blog-content-img-wrapper">
        <img src="https://assets.fedevel.com/blog/2019/10/05f18-01-uboot-without-eth-module.jpg" alt="01 uboot without eth module" />
    </div>

    <div class="blog-content-text">
        <i>Picture: Memory test (Ethernet connected)</i>
    </div>
    <div class="blog-content-img-wrapper">
        <img src="https://assets.fedevel.com/blog/2019/10/f9e30-03-stresstest-mem-module.jpg" alt="03 stresstest mem module" />
    </div>

    <div class="blog-content-text">
        <i>Picture: CPU test + Memory test (Ethernet unplugged)</i>
    </div>
    <div class="blog-content-img-wrapper">
        <img src="https://assets.fedevel.com/blog/2019/10/32526-05-stresstest-cpumem-eth-unplugged-module.jpg" alt="05 stresstest cpu+mem eth unplugged module" />
    </div>

    <div class="blog-content">
        <h2 class="blog-content-heading">If you use a hot air gun, how the heat will spread on PCB?</h2>
        This was also an interesting experiment, we used a hot air gun (you can see it on the right picture) to heat up a small PCB. Notice, how the middle GND exposed pad is much colder then the area without copper <i>(note: the result may be affected by the shiny surface of golden areas).</i>
    </div>

    <div class="blog-content-img-wrapper">
        <img src="https://assets.fedevel.com/blog/2019/10/30c3e-sps-bottom-gun-rear1-180c2b0c-comparision.jpg" alt="SPS bottom gun rear1 180°C comparision" />
    </div>
</div>

A different look at your PCB – Infrared

<div class="entry-content">
    <div class="jetpack-video-wrapper"><span class="embed-youtube" style="text-align:center; display: block;"><iframe src="https://www.youtube.com/embed/67WhV0EDqCA" class="youtube-player" width="740" height="416.418" frameborder="0" allowfullscreen></iframe></span>
    </div>
    <div class="blog-content">
        This video will show you how the layers of a multi-layer PCB are put together. Thank you very much to our PCB manufacturer SQP International, where I could make this video.
    </div>
    <div class="blog-content-chapters">
        <div>
            Chapters:
        </div>
        <ul class="chapters-list">
            <li class="chapters-list-item">
                <span class="chapters-time">00:00</span><span class="chapters-text">Intro</span>
            </li>
            <li class="chapters-list-item">
                <span class="chapters-time">00:15</span><span class="chapters-text">Ingredients</span>
            </li>
            <li class="chapters-list-item">
                <span class="chapters-time">05:25</span><span class="chapters-text">Techniques</span>
            </li>
            <li class="chapters-list-item">
                <span class="chapters-time">06:11</span><span class="chapters-text">Plating</span>
            </li>
            <li class="chapters-list-item">
                <span class="chapters-time">08:09</span><span class="chapters-text">Drilling</span>
            </li>
        </ul>
    </div> 
    <div class="blog-content-links">
        <div>
            Links:
        </div>
        <ul class="links-list">
            <li class="links-list-item"><a href="http://www.PCBone.com/">PCB manufacturer SQP International</a></li>
        </ul>
    </div> 
</div>


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