转一篇关于 Type c 数据线文章
之前买了条贝尔金 Type c 数据线，比较家里几条千元级的USB2.0音响数据线，连MacBook Pro 2016 接解码器，发现贝尔金的Type c数据线比手上任何一条USB 2.0加转接头的音响数据线都要音质更好和更真实自然，结果令人存疑，我想这篇文章也许有所启发。------------------------------------
转自 Google+ https://plus.google.com/+BensonLeung/posts/LH4PPgVrKVN
My team at Google has been very big proponents and innovators of USB Type-C. I've worked on two Pixel products now that use the connector and its related technologies (Power Delivery, Alternate Mode, USB 3.1). It really is an amazing little connector.
However, now that there are more and more Type C products rolling out from Nexus, One+, Nokia, and more, this I have found painfully true : USB Type-C will only be as good as its ecosystem, and more specifically, the worst of its ecosystem.
I have started reviewing USB cables on Amazon because I have gotten fed up with the early cables from 3rd party vendors that so blatantly flaunt the specification and I want to hold them to task.
You may not just get weird behavior from your devices with these bad cables... What some these vendors are doing is downright dangerous.
I've been contemplating setting up a blog where I document bad cables and perhaps give some insights into USB Type C as well.
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亚马逊上的测评: http://www.amazon.com/gp/cdp/member-reviews/A25GROL6KJV3QG?ie=UTF8&display=public&page=1&sort_by=MostRecentReview
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测评的重点是 USB 接头内的上拉电阻
USB Type C 规范内限制了旧式转接头必需使用56k 欧姆的上拉电阻，以表示设备须根据旧有的 USB 规范决定充电电流
不过有些转接头却使用了只有 USB Type C 新规范才能使用的 10k 欧姆上拉电阻，表示设备可以使用 3A 充电电流。如果将设备连接到不能输出 3A 电流的电脑或充电器，可能会导致电脑或充电器受损甚至着火！
目测某宝上应该没有合规格的线和转接头，好像就连一加的官方线也不合规格
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5X 可以使用此方法测试 USB 线:
在电脑上运行指令
adb shell dmesg
在输出找寻 "Avail curr from USB"
会见到类似这样的文本
dwc3 f9200000.dwc3: Avail curr from USB = 3000
如果见到是 3000 就表示不合规格，合格应为 500 或 1500
这个是充电要求吧，数据传输是分开的，理论上USB电气隔离后不影响。
当然实测转接头影响不小，少一个香炉总是好的。
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