<div class="entry-content">
    <div class="jetpack-video-wrapper"><span class="embed-youtube" style="text-align:center; display: block;"><iframe
                class="youtube-player"
                src="https://www.youtube.com/embed/IuKfJN27w_g?version=3&rel=1&showsearch=0&showinfo=1&iv_load_policy=1&fs=1&hl=en&autohide=2&wmode=transparent"
                allowfullscreen="true"
                style="border: 0px; display: block; margin: 0px; width: 740px; height: 416.418px;"
                sandbox="allow-scripts allow-same-origin allow-popups allow-presentation"
                data-ratio="0.5627272727272727" data-width="1100" data-height="619"></iframe></span>
    </div>
    <div class="blog-content">
Measuring and burning PCB tracks. 
    </div>
    
    <div class="blog-content-links">
        <div>
            Links:
        </div>
        <ul class="links-list">
            <li class="links-list-item"><a href="https://www.linkedin.com/in/eric-bogatin-368860/">Eric's Linked In</a></li>
            <li class="links-list-item"><a href="https://youtu.be/LQ20GBonRmA">PCB Simulation vs. Real Board - DC Currents and Voltage drop</a></li>
            <li class="links-list-item"><a href="https://fedevel.com/courses">FEDEVEL Online courses</a></li>
        </ul>
    </div>  
</div>

How Much Current Will Destroy a PCB Track? | Track resistance measurements

<div class="entry-content">
    <div class="jetpack-video-wrapper"><span class="embed-youtube" style="text-align:center; display: block;"><iframe
                class="youtube-player"
                src="https://www.youtube.com/embed/UpFd6ubqTLI?version=3&rel=1&showsearch=0&showinfo=1&iv_load_policy=1&fs=1&hl=en&autohide=2&wmode=transparent"
                allowfullscreen="true"
                style="border: 0px; display: block; margin: 0px; width: 740px; height: 416.418px;"
                sandbox="allow-scripts allow-same-origin allow-popups allow-presentation"
                data-ratio="0.5627272727272727" data-width="1100" data-height="619"></iframe></span>
    </div>
    <div class="blog-content">
Op-amps explained: how they work and what are their important parameters. 
    </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">00:29</span><span class="chapters-text">Why to use operational amplifier</span></li>
            <li class="chapters-list-item"><span class="chapters-time">02:21</span><span class="chapters-text">Ideal op amp</span></li>
            <li class="chapters-list-item"><span class="chapters-time">07:00</span><span class="chapters-text">How inverting op amp works</span></li>
            <li class="chapters-list-item"><span class="chapters-time">12:13</span><span class="chapters-text">How non-inverting op amp works</span></li>
            <li class="chapters-list-item"><span class="chapters-time">13:25</span><span class="chapters-text">Op amp working as a buffer</span></li>
            <li class="chapters-list-item"><span class="chapters-time">15:42</span><span class="chapters-text">Op amp working as a current reference</span></li>
            <li class="chapters-list-item"><span class="chapters-time">20:09</span><span class="chapters-text">Input offset voltage</span></li>
            <li class="chapters-list-item"><span class="chapters-time">28:15</span><span class="chapters-text">Input offset voltage simulation</span></li>
            <li class="chapters-list-item"><span class="chapters-time">30:50</span><span class="chapters-text">Input offset voltage measurement</span></li>
            <li class="chapters-list-item"><span class="chapters-time">35:04</span><span class="chapters-text">Input bias current</span></li>
            <li class="chapters-list-item"><span class="chapters-time">37:20</span><span class="chapters-text">Input bias current measurement</span></li>
            <li class="chapters-list-item"><span class="chapters-time">41:00</span><span class="chapters-text">Op-amp Bandwidth</span></li>
            <li class="chapters-list-item"><span class="chapters-time">43:59</span><span class="chapters-text">Op-amp Bandwidth measurement</span></li>
            <li class="chapters-list-item"><span class="chapters-time">48:50</span><span class="chapters-text">Op-amp Bandwidth simulation</span></li>
            <li class="chapters-list-item"><span class="chapters-time">50:23</span><span class="chapters-text">Operational amplifier slew rate</span></li>
            <li class="chapters-list-item"><span class="chapters-time">51:28</span><span class="chapters-text">Slew rate simulation</span></li>
            <li class="chapters-list-item"><span class="chapters-time">53:07</span><span class="chapters-text">Slew rate measurement</span></li>
            <li class="chapters-list-item"><span class="chapters-time">55:48</span><span class="chapters-text">Slew rate impact to sinusoidal output</span></li>
            <li class="chapters-list-item"><span class="chapters-time">1:00:28</span><span class="chapters-text">Op amp noise</span></li>
            <li class="chapters-list-item"><span class="chapters-time">1:07:38</span><span class="chapters-text">Op amp noise measurement</span></li>
            <li class="chapters-list-item"><span class="chapters-time">1:10:57</span><span class="chapters-text">Op amp noise simulation</span></li>
            <li class="chapters-list-item"><span class="chapters-time">1:15:36</span><span class="chapters-text">Input and output voltage swing</span></li>
            <li class="chapters-list-item"><span class="chapters-time">1:16:45</span><span class="chapters-text">Common mode range</span></li>
            <li class="chapters-list-item"><span class="chapters-time">1:19:14</span><span class="chapters-text">Common mode range simulation</span></li>
            <li class="chapters-list-item"><span class="chapters-time">1:20:04</span><span class="chapters-text">Common mode range measurement</span></li>
            <li class="chapters-list-item"><span class="chapters-time">1:22:31</span><span class="chapters-text">Op amp output range</span></li>
            <li class="chapters-list-item"><span class="chapters-time">1:28:17</span><span class="chapters-text">Op-amp stability</span></li>
            <li class="chapters-list-item"><span class="chapters-time">1:29:59</span><span class="chapters-text">Op-amp stability simulation</span></li>
            <li class="chapters-list-item"><span class="chapters-time">1:32:20</span><span class="chapters-text">Op-amp stability measurement</span></li>
            <li class="chapters-list-item"><span class="chapters-time">1:38:51</span><span class="chapters-text">pH Electrometer solution - practical example</span></li>
            <li class="chapters-list-item"><span class="chapters-time">1:46:19</span><span class="chapters-text">Measuring pH</span></li>
    </div>
    
    <div class="blog-content-links">
        <div>
            Links:
        </div>
        <ul class="links-list">
            <li class="links-list-item"><a href="https://www.linkedin.com/in/arthur-kay-a5201929/">Arthur´s LinkedIn</a></li>
            <li class="links-list-item"><a href="https://www.linkedin.com/in/zach-olson-vt/">Zach´s LinkedIn</a></li>
            <li class="links-list-item"><a href="https://fedevel.com/courses">FEDEVEL Online courses</a></li>
        </ul>
    </div>  
</div>

Everything Important About OP AMP (Operational amplifier)

<div class="entry-content">
    <div class="jetpack-video-wrapper"><span class="embed-youtube" style="text-align:center; display: block;"><iframe
                class="youtube-player"
                src="https://www.youtube.com/embed/pdzQ-kgLbFw?version=3&rel=1&showsearch=0&showinfo=1&iv_load_policy=1&fs=1&hl=en&autohide=2&wmode=transparent"
                allowfullscreen="true"
                style="border: 0px; display: block; margin: 0px; width: 740px; height: 416.418px;"
                sandbox="allow-scripts allow-same-origin allow-popups allow-presentation"
                data-ratio="0.5627272727272727" data-width="1100" data-height="619"></iframe></span>
    </div>
    <div class="blog-content">
This video includes explanation of battery charging and safety schematic circuits. 
    </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">01:33</span><span class="chapters-text">Types of cells and batteries</span></li>
            <li class="chapters-list-item"><span class="chapters-time">05:43</span><span class="chapters-text">CID and PTC battery protection</span></li>
            <li class="chapters-list-item"><span class="chapters-time">08:44</span><span class="chapters-text">Prismatic cells</span></li>
            <li class="chapters-list-item"><span class="chapters-time">10:37</span><span class="chapters-text">Pouch cells</span></li>
            <li class="chapters-list-item"><span class="chapters-time">16:02</span><span class="chapters-text">Lithium Ion (Li-Ion)</span></li>
            <li class="chapters-list-item"><span class="chapters-time">17:28</span><span class="chapters-text">Peak charge and nominal voltage, end of discharge voltage</span></li>
            <li class="chapters-list-item"><span class="chapters-time">20:30</span><span class="chapters-text">Thermal runaway</span></li>
            <li class="chapters-list-item"><span class="chapters-time">22:32</span><span class="chapters-text">Lithium Iron Phosphate (LiFePO4)</span></li>
            <li class="chapters-list-item"><span class="chapters-time">26:15</span><span class="chapters-text">Nickel Metal Hydride (NIHM)</span></li>
            <li class="chapters-list-item"><span class="chapters-time">29:23</span><span class="chapters-text">How cells are connected together</span></li>
            <li class="chapters-list-item"><span class="chapters-time">32:31</span><span class="chapters-text">Battery testing standards</span></li>
            <li class="chapters-list-item"><span class="chapters-time">36:38</span><span class="chapters-text">Battery safety circuit - Safety features</span></li>
            <li class="chapters-list-item"><span class="chapters-time">44:28</span><span class="chapters-text">Battery safety schematic circuit explained</span></li>
            <li class="chapters-list-item"><span class="chapters-time">55:31</span><span class="chapters-text">Safety circuit integrated in batteries, shipping and transport</span></li>
            <li class="chapters-list-item"><span class="chapters-time">1:06:04</span><span class="chapters-text">Battery charging schematic circuit explained</span></li>
            <li class="chapters-list-item"><span class="chapters-time">1:21:01</span><span class="chapters-text">Battery charging schematic circuit example 2</span></li>
            <li class="chapters-list-item"><span class="chapters-time">1:27:23</span><span class="chapters-text">About Alex</span></li>
            </span></li>
        </ul>
    </div>

    <div class="blog-content-links">
        <div>
            Links:
        </div>
        <ul class="links-list">
            <li class="links-list-item"><a href="https://www.linkedin.com/in/alex-norman-eetengineer/">Alex´ LinkedIn</a></li>
            <li class="links-list-item"><a href="https://www.youtube.com/@eetengineer">Alex´s Youtube</a></li>
            <li class="links-list-item"><a href="https://fedevel.com/courses">FEDEVEL Online courses</a></li>
        </ul>
    </div>  
</div>

Powering Up Your Board From a Battery? You need to know this ...

<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
                class="youtube-player"
                src="https://www.youtube.com/embed/67WhV0EDqCA?version=3&rel=0&showsearch=0&showinfo=1&iv_load_policy=1&fs=1&hl=en&autohide=2&wmode=transparent"
                allowfullscreen="true"
                style="border: 0px; display: block; margin: 0px; width: 740px; height: 416.418px;"
                sandbox="allow-scripts allow-same-origin allow-popups allow-presentation"
                data-ratio="0.5627272727272727" data-width="1100" data-height="619"></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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