标签: sink

随着影音消费电子产品市场持续强势发展，产品音频及视频信号的传输便更占重要地位，前一篇 HDMI 2.1 常见认证测试问题剖析– Part I : Source ，本篇文章将接续分享 Sink 产品，自百佳泰丰富认证经验中，盘点出四项 HDMI 2.1 Sink 产品认证测试的常见问题！ 新传输模式FRL产生的测试变动 在Source篇中有提到， HDMI 2.1最大的变更是新增了FRL (Fixed Rate Link)传输模式来取代旧有的TMDS模式 ，透过FRL可以将带宽由 TMDS的18G 提升到 FRL的48G ，藉以传输 8K Video 。FRL讯号在传输之前需先通过Link Training的沟通，因此在FRL的Electrical测试也会较复杂。以往TMDS的Electrical测试，只须将测试治具端的+5V连接到Power Supply，提供5V 电压，即可仿真成Sink连接到Source的状态来进行Electrical测试。 FRL Electrical测试必须由特殊的设备模拟成Source来跟Sink进行Link Training程序，且当Sink接收到Generator的BERT讯号后，Sink的缓存器中会记录error count，此时Source会透过SCDC去读取Sink的error count并判断是否符合SPEC规范。 百佳泰自行研发 SCDC/EDID emulator – AJSC-1 已通过协会认可，成为标准测试设备 。这个test fixture除了可模拟成Source去跟Sink进行Link Training外，也可透过SCDC去读取error count。 透过百佳泰的SCDC/EDID EMULATOR – AJSC-1进行LINK TRAINING 带宽上限不再阻挡传输！Max_TMDS 的新规宣告 HDMI Source必须根据 Sink 的 EDID 内容来决定可传输的Video，其中可传输Video的带宽上限会取决于 EDID 中的 Max_ TMDS_Clock 和 Max_TMDS_Character _Rate ，前者负责 25MHz到340MHz ，后者负责 345MHz到600MHz 。 以往在定义这两个数值时会去参考 1.4 和 2.1 CDF 中 的分辨率来决定最高带宽，但这种做法存在一个盲点，Source可能 无法传输介于 Max_TMDS_Clock 和 340MHz 之间的分辨率给Sink 。举例 1.4 的 Max_TMDS_Clock 为 225MHz ，表示Source 无法传输225~340MHz 的Video给Sink，为了弥补这个 兼容性问题 ， HDMI Forum 在2022年初公布的 2.1a SPEC 中规定，只要 2.1 Sink 有宣告 Max_TMDS_Character_Rate(345MHz到600MHz)，Max_TMDS_Clock必须宣告为 340MHz 。日后HDMI Forum也有可能将此规定直接定义到Compliance Test中。 产品Repeater功能为何失效？ 目前有些电子白板或是TV，为了方便展示，除了本身是Sink外还同时具备了 Repeater 功能，可以把接收到的讯号传送给下游的 Sink 。在设计这类产品时需注意到 Repeater的功能是否能满足SPEC的规范 。 下图是一个 non-compliant 的 Repeater 案例。 REPEATER OUTPUT必须符合SOURCE规范 这台4K TV除了本身是Sink外，也可以将接收到的讯号Pass-through给下游的 2K TV ，因此具备了Repeater 功能。 Repeater 和 Sink 共享了相同的EDID ，因此当 Sink 收到什么样的讯号，就会将该讯号原封不动的传给下游 Sink 。这种设计 违反了SPEC规定 ，可能会造成 兼容性的问题 。 例如4K TV接收了上游Source的4K讯号，除了显示在本身的Panel外也把4K讯号Pass-through给下游的2K TV，因下游的 2K TV只具备接收2K讯号的能力，故无法显示画面 。SPEC规范Repeater Output必须符合Source规范，其中一项规定是 Source必须根据Sink的EDID内容，传输给Sink可支持的Video 。 为了解决这个问题，拥有多年HDMI测试经验的百佳泰建议可依以下方案做设计变更： 方案一： 将Repeater改为读取 下游Sink的EDID ，并根据EDID的内容来决定输出的Video。 方案二： Repeater仍旧 跟Sink共享EDID ，但会根据下游的EDID内容来转换Video并输出，例如将接收到的4K Video转成2K Video后再输出。 4K规范别漏掉EDID测试必留意 HDMI的Video规格随着 CTA (原CEA)的更新不断的增加，加上为了让 Sink 可以有更好的 兼容性 ，有些厂商会将自家HDMI产品的规格设计成 同时拥有二个EDID让使用者切换 ， 一个EDID宣告1.4b的Video ， 另一个EDID宣告2.1的Video 。近期 HDMI Forum 在审核 2.1 报告时有注意这个现象，要求即便是 1.4b的EDID 也 必须符合2.1 SPEC，须执行2.1相关EDID测试 。 比较容易忽略的应该是 4K@24/25/30Hz ，在 1.4b 的 SPEC 中，因当时是跟随 CEA861-D 的规范，尚未规范到 4K Video ，因此 HDMI 协会在 Vendor Specific Data Block 中定义了 HDMI_VIC_1,2,3,4 来表示 4K@30/25/24/24 (SMPTE) Video 。 而 HDMI 2.1 SPEC 是跟随 CTA-816-H ，已定义 4K@30/25/24/24(SMPTE)的VIC为95,94,93, 98。为了符合 HDMI 2.1 SPEC 的规范， 2.1 Sink 产品的 EDID 内容，只要有支持4K@30/25/24/24(SMPTE)，就 必须同时在VSDB中写入HDMI_VIC_1,2,3,4，VDB中则写入VIC95,94,93,98 。 从上述的分享，相信各位读者对 于HDMI 2.1 Source跟Sink产品 ，在设计上要注意哪些地方，应该有帮助。目前 HDMI 2.1 认证测试大约一季会更新一次测试内容，主要是新增一些Protocol测项，测试规范是来自于测试规格书 CTS (Compliance Test Specification) 。虽然测试项目是来自于CTS，但CTS是源自于Generic Compliance Test Specification，为了加速取证时程、减少错误的产生，建议可以预先掌握Generic Compliance Test Specification的测试内容，随时注意HDMI协会公布之讯息。

Most electronic, mechanical, and thermal engineers think of how to keep the temperature of their IC or printed circuit board below some maximum allowable value. Others are more worried about the overall enclosure, which can be range from a self-contained package such as a DVR to a standard rack of boards and power supplies.   Basic techniques for getting heat from an IC, board, or enclosure involve one or more of heat sinks, heat spreaders (PC-board copper), head pipes, cold plates, and fans; it can sometimes move up to more-active cooling approaches including air conditioning or embedded pipes with liquid flow. That's all well and good, but obviously not good enough for the megawatts of a "hyperscale" data center. (If you are not sure what a hyperscale data center is, there's a good explanation here ). While there is no apparent formal standard on the minimum power dissipation to be considered hyperscale, you can be sure it's in the hundreds of kilowatt to megawatt range.   But where does all that heat go? Where is the "away" to which the heat is sent? If you’re cooling a large data center, that "away" to hard to get to, and doesn't necessarily want to take all that heat you are dissipating.   A recent market study from a BSRIA offered some insight in the hyperscale data-center cooling options and trends. I saw a story on the report in the November issue of Cabling Installation Maintenance , a publication which gives great real-world perspective into the nasty details of actually running all those network cables, building codes, cabling standards, and more. (After looking through this magazine you'll never casually say, it’s "no big deal, it’s just an RJ-45 connector" again.)   BSRIA summarized their report and used a four-quadrant graph (below) of techniques versus data-center temperatures to clarify what is feasible and what is coming on strong. Among the options are reducing dissipation via variable-speed drives and modular DC supplies, cooling techniques from liquid cooling to adiabatic evaporative cooling, or allowing a rise in server-inlet temperature. The graph also shows the growth potential versus investment level required for each approach; apparently, adiabatic/evaporative cooling is the "rising star."   Cooling approaches for hyperscale data centers encompass basic dissipation reduction, liquid cooling, and adiabatic/evaporative cooling, according to this analysis from BSRIA Ltd, with the latter a "rising star."   When you are worried about cooling your corner of a PC board, it's easy to forget that it's not enough to succeed in that goal; you have to think of the next person who will have to deal with the heat which you so nicely spirited away. That's why I am often wary of PC-board heat spreaders, unless the design has been thermally modeled "across the board", so to speak: they move the heat from your IC to the next one, and so make their thermal headache more difficult.   Although I know I won't be involved with design of such hyperscale cooling, I need to learn more about thermal principles, including adiabatic/evaporative cooling. It still hurts that a very long time ago, when I was told to take an engineering course on "thermal physics" to learn basics, I was misled. It turned out the course was about the personal thermal lives of atoms and molecules, and had nothing at all to do with "thermal" as engineers need to know it: heat, heat flow, thermal modeling, temperature rise, cooling techniques, and more. In contrast, "thermal physics" is what Einstein used in one his is five 1905 papers, " Über die von der molekularkinetischen Theorie der Wärme geforderte Bewegung von in ruhenden Flüssigkeiten suspendierten Teilchen " ("On the Motion of Small Particles Suspended in a Stationary Liquid, as Required by the Molecular Kinetic Theory of Heat"), but hey, he wasn't worried about cooling a hot component!

I don’t know about you, but I always enjoy seeing something new, so today started off with a bang when I received an email from my chum Rick Curl saying: "What’s interesting about this is not so much the material being presented, but the method they chose to present it."   This somewhat cryptic message was accompanied by two links: https://youtu.be/aDorTBEhEtk https://youtu.be/ihv4f7VMeJw   In turn, these links were augmented with the following instruction: "You MUST open the two links in two different browsers -- not two tabs in one browser."   "What could this possibly be about?" I wondered, but I'm always "game for a laugh," so I did as I was instructed.   This really is rather cool. I'm sure that as kids we all heard that water spirals anticlockwise when exiting a sink, bath, or toilet in the Northern hemisphere and clockwise in the Southern hemisphere. This is due to the Coriolis Effect, which results in a deflection of moving objects when the motion is described relative to a rotating reference frame.   The problem is that when one actually tries to observe this for oneself (and haven’t we all done so?), the water doesn’t seem to want to follow the rules. Take the following image of a dual sink, for example. Although it's hard to make out here (you can see it in one of the videos mentioned above), the water in the left-hand sink is spiraling anticlockwise, while the water in the right-hand sink is spiraling clockwise. Even worse, the narrator notes that the water sometimes drains one way and sometimes the other way.     I think it's fair to say that we all eventually come to the conclusion that the way in which the water exits is predominantly driven by the design of the artifact in question, and that the Coriolis effect is too slight to make itself apparent in these small-scale test cases. So I'm well-impressed by the two guys in these videos who determined to provide a brilliant example of the effect in action.   As Rick noted, you have to open each video in a separate browser and have the two videos running side-by-side (the videos include "5-4-3-2-1" images at the beginning to facilitate your syncing them up).   Anticlockwise in the Northern hemisphere.     Clockwise in the Southern hemisphere.   Of particular interest to me is the fact that the Northern hemisphere video was captured where I currently hang my hat here in Huntsville, Alabama, USA. I wish I'd known it was taking place, because I would love to have been there to see it happen.   I think that these videos would be great for teachers to show kids at school; don’t you? Have you seen any other videos like this that manage to be highly educational and fun at the same time?

Jim Smith, president of Electronics Manufacturing Sciences Inc., sent me an email in response to my previous post on engineers who cannot solder. He said the people at his company focus on soldering, because it is both the heart of electronics manufacturing and the process that causes the most problems. For these reasons, his company specialises in soldering training/education, certification, and process development. I reproduce Jim's email in its entirety as follows: Hello Max. I came upon your column by fortuitous accident. You wrote with great insight into a critical problem in the US electronics industry. And, as I wrote hurriedly in my posted response, the problem is much greater than most people realise. Almost no one—not just engineers—knows how to solder. Most of those who take pride in their soldering skills are unaware that their technique is faulty. I've been developing soldering processes, troubleshooting soldering process problems, and teaching all forms of soldering for close to 50 years. I've worked with hundreds of companies—from start-ups to the biggest corporations—all over the world, and I can tell you without fear of contradiction that lack of soldering knowledge is more prevalent now than ever. The prevailing belief holds that a cosmetically attractive solder connection must be a good solder connection. But this is not necessarily true, especially if a soldering iron was involved in making that connection. At soldering iron temperatures, solder will stick to oxides and give the false appearance of a proper connection (you can read more in my document The Metallurgy of Heat-Induced Soldering ). The compromised integrity of the solder bond itself affects reliability under conditions of vibration or thermal cycling, but the far more serious reliability consequence consists of degradation inside components, especially ICs. Applying such high temperature long enough to achieve adherence of solder to the oxidized surface causes the wire bonds inside ICs to degrade to an extent that would require decades of product use. The phenomenon is known as the "purple plague" ( click here to see some discussions on this phenomenon). The damage is invisible, so everyone blames the component manufacturer when devices fail prematurely, but the root cause is improper soldering technique. Today's hand soldering procedure was developed in the vacuum tube era for attaching wires to sockets. Those materials could not be damaged by overheating. Rather, the challenge was how to get enough heat into big metal objects using irons that were not very efficient at turning electricity into heat. The focus was entirely on keeping the parts hot enough, long enough so the solder would flow adequately without freezing. When solid-state devices entered the picture, we began soldering the components themselves rather than their sockets. To prevent heat damage to the component, metal clips known as heat sinks were placed on leads next to the component body. This allowed the excess soldering heat to flow into the sink rather than stressing the component. As parts got smaller, however, there wasn't room for heat sinks, so they disappeared from the work instructions, but every trainee continued to be told to use the same technique developed for wiring vacuum tube assemblies. This is insane. Complicating matters is the fact that electronics "soldering" has mostly been welding. Surfaces to be soldered have mostly been tin or tin/lead and those surfaces melted at or below 450°F (232.22°C), which is much lower than the temperature reached by those surfaces during "soldering." When a surface melts during application of solder, the heavy liquid solder easily pushes oxides and even contaminants aside; the liquid metals (solder and component surface) can then flow together. It's hard to imagine a less challenging application. But the lead-free movement and fear of tin whiskers have caused the use of new component surface metals that have much higher melting temperatures. Those surfaces don't melt during soldering, which means that the industry—for the first time in its history—must actually solder. But they (including most of the people who set industry standards) don't know how to solder; they only know how to weld. In short, no one understands wetting forces and solderability. Nor do they have meaningful understanding of flux properties ranging from ionic contamination (acid residue) hazards to hygroscopic solids. Soldering is the heart of electronics manufacturing, and lack of process knowledge is killing industry. Touchup (most of it unrecognised by management; what we used to call "the hidden factory") and rework are rampant. Engineers get no coherent education about soldering. I don't know of any course aside from my company's Science of Soldering that teaches the chemistry, metallurgy, and physics of soldering. Operators and technicians get "certified" in the idiotic ritual of memorising A-610 or J-STD-001 acceptance rules so they can answer open-book multiple-choice questions. The training tells them the appearance of acceptable solder connections but provides no knowledge at all of how to meet those requirements (aside from pushing the solder around with the iron until it finally achieves a shape everyone can live with). Rather than rewarding operators who bring material and process problems to management's attention so the problems can be corrected, the industry places highest value on assemblers who can produce visually acceptable connections with un-solderable materials. The whole system is like teaching pilots how to fly simply by giving them route maps without any instructions about how to operate the plane itself. (My 2011 Assembly Magazine column about the damage done by A-610 and J-STD-001 training can be found by clicking here .) To sum up, you've opened the journalistic door to the single most important challenge facing electronics manufacturing today. Thanks for your time and the outstanding column. Best wishes, Jim. I don't know about you, but I think he is passionate about soldering. Also, since he says such nice things about me and my writings, I think it's fair to assume that he is a very clever and discerning person. However, I fear he has thrown down the gauntlet to some parties with an interest in certain industry standards. I await everyone's comments and feedback with bated breath.  

As a follow up to my previous post on engineers who cannot solder, I received an email from Jim Smith, president of Electronics Manufacturing Sciences Inc. He said the people at his company focus on soldering, because it is both the heart of electronics manufacturing and the process that causes the most problems. For these reasons, his company specialises in soldering training/education, certification, and process development. I reproduce Jim's email in its entirety as follows: Hello Max. I came upon your column by fortuitous accident. You wrote with great insight into a critical problem in the US electronics industry. And, as I wrote hurriedly in my posted response, the problem is much greater than most people realise. Almost no one—not just engineers—knows how to solder. Most of those who take pride in their soldering skills are unaware that their technique is faulty. I've been developing soldering processes, troubleshooting soldering process problems, and teaching all forms of soldering for close to 50 years. I've worked with hundreds of companies—from start-ups to the biggest corporations—all over the world, and I can tell you without fear of contradiction that lack of soldering knowledge is more prevalent now than ever. The prevailing belief holds that a cosmetically attractive solder connection must be a good solder connection. But this is not necessarily true, especially if a soldering iron was involved in making that connection. At soldering iron temperatures, solder will stick to oxides and give the false appearance of a proper connection (you can read more in my document The Metallurgy of Heat-Induced Soldering ). The compromised integrity of the solder bond itself affects reliability under conditions of vibration or thermal cycling, but the far more serious reliability consequence consists of degradation inside components, especially ICs. Applying such high temperature long enough to achieve adherence of solder to the oxidized surface causes the wire bonds inside ICs to degrade to an extent that would require decades of product use. The phenomenon is known as the "purple plague" ( click here to see some discussions on this phenomenon). The damage is invisible, so everyone blames the component manufacturer when devices fail prematurely, but the root cause is improper soldering technique. Today's hand soldering procedure was developed in the vacuum tube era for attaching wires to sockets. Those materials could not be damaged by overheating. Rather, the challenge was how to get enough heat into big metal objects using irons that were not very efficient at turning electricity into heat. The focus was entirely on keeping the parts hot enough, long enough so the solder would flow adequately without freezing. When solid-state devices entered the picture, we began soldering the components themselves rather than their sockets. To prevent heat damage to the component, metal clips known as heat sinks were placed on leads next to the component body. This allowed the excess soldering heat to flow into the sink rather than stressing the component. As parts got smaller, however, there wasn't room for heat sinks, so they disappeared from the work instructions, but every trainee continued to be told to use the same technique developed for wiring vacuum tube assemblies. This is insane. Complicating matters is the fact that electronics "soldering" has mostly been welding. Surfaces to be soldered have mostly been tin or tin/lead and those surfaces melted at or below 450°F (232.22°C), which is much lower than the temperature reached by those surfaces during "soldering." When a surface melts during application of solder, the heavy liquid solder easily pushes oxides and even contaminants aside; the liquid metals (solder and component surface) can then flow together. It's hard to imagine a less challenging application. But the lead-free movement and fear of tin whiskers have caused the use of new component surface metals that have much higher melting temperatures. Those surfaces don't melt during soldering, which means that the industry—for the first time in its history—must actually solder. But they (including most of the people who set industry standards) don't know how to solder; they only know how to weld. In short, no one understands wetting forces and solderability. Nor do they have meaningful understanding of flux properties ranging from ionic contamination (acid residue) hazards to hygroscopic solids. Soldering is the heart of electronics manufacturing, and lack of process knowledge is killing industry. Touchup (most of it unrecognised by management; what we used to call "the hidden factory") and rework are rampant. Engineers get no coherent education about soldering. I don't know of any course aside from my company's Science of Soldering that teaches the chemistry, metallurgy, and physics of soldering. Operators and technicians get "certified" in the idiotic ritual of memorising A-610 or J-STD-001 acceptance rules so they can answer open-book multiple-choice questions. The training tells them the appearance of acceptable solder connections but provides no knowledge at all of how to meet those requirements (aside from pushing the solder around with the iron until it finally achieves a shape everyone can live with). Rather than rewarding operators who bring material and process problems to management's attention so the problems can be corrected, the industry places highest value on assemblers who can produce visually acceptable connections with un-solderable materials. The whole system is like teaching pilots how to fly simply by giving them route maps without any instructions about how to operate the plane itself. (My 2011 Assembly Magazine column about the damage done by A-610 and J-STD-001 training can be found by clicking here .) To sum up, you've opened the journalistic door to the single most important challenge facing electronics manufacturing today. Thanks for your time and the outstanding column. Best wishes, Jim. I don't know about you, but I think he is passionate about soldering. Also, since he says such nice things about me and my writings, I think it's fair to assume that he is a very clever and discerning person. However, I fear he has thrown down the gauntlet to some parties with an interest in certain industry standards. I await everyone's comments and feedback with bated breath.