为什么电话连接器是微型USB型B而不是微USB型AB

大多数电话是用来作为连接到PC的设备的吗？Ruben



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    Mostly the phone is used as a device connected to a PC?
 
/Ruben

这两个装置是相同的，差异是在电缆的两端。这就是为什么连接器有5个引脚而不是4个。



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The two devices are identical, the difference is in the two ends of the cable. That is why the connector has 5 pins instead of 4.
 

嗨，如果你连接2个OTG设备，需要的电缆是“特殊的”（第五个信号）。原因是，当它开始枚举时，每个人都必须知道它是作为主机或设备启动的。电缆的一端有一个第五个信号，称为“感测”或“ID”。如果它连接到GND，那么这个侧是主机，而另一侧是。设备（感测或ID没有连接）。



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    Hi,
If you connect 2 OTG devices, the cable needed is "special" (5th signal).
The reason is that when it starts enumeration each must know if it starts as HOST or DEVICE.
One end of the cable has a 5th signal called SENSE or ID.
If it is connected to GND then this side is the HOST and the other side is device (SENSE or ID is not connected).
Regards
 

电话可以连接到PC：电话连接器是微型USB型B，因为VBUS是由PC供电的。但是电话可以连接到电话：这就是为什么，电话连接器是微USB型AB的逻辑。问题是当我检查电话时，我看到微型USB连接器是B型而不是AB型。用微型USB B型连接器，你不能使用微USB型电缆和微USB A型。B连接器，您可以使用所有Micro USB电缆类型：为什么电话制造商不使用微USB AB连接器与所有电缆类型兼容？我认为这是有原因的，不是吗？我必须开发一个USB OTG产品（不是一个电话），我想知道我是否必须使用微型USB类型的AB或B型。



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A phone can be connected to a PC : it would be normal that phone connector is micro-USB type B because VBUS is powered by PC.
... But a phone can be connected to a phone : it is why, it would be more logic that phone connector is micro-USB type AB.
Problem is when I check a phone, I see micro-USB connector is type B and not type AB. With micro-USB type B connector, you can't use micro-USB type A cable and with micro-USB type AB connector, you can use all micro-USB cable type : why phone manufacturers doesn't use micro-USB type AB connector to be compatible with all cable type ? I think there is a reason, isn't it ?
 
I must develop a USB OTG product (not a phone) and I would to know if I must use micro-USB type AB or type B.
 

我从未见过微型AB插座。这个想法似乎已经悄无声息地消失了，所有的电缆两端都有微型B插头。



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    I've never seen a micro-AB receptacle.
The idea seems to have quietly died, and all the cables just have micro-B plugs at both ends.

的确。我见过一些微型手机套接字（主要是在评估套件上），但它们似乎已经消失了。我怀疑手机制造商做出务实的决定：最好不要遵守标准，而不是那些火腿拳击手打破插座试图堵住Bug Changin的投诉。G电缆在上下颠倒，微型B型插座的梯形形状使它比矩形微型机更容易进行定向。唯一的时间对我来说是一个问题是树莓Pi-零，它也使用了微型B插座，它应该是微AB，我必须买一个NO。N兼容的微型B到全尺寸USB套接字适配器，即使我有一个非常好的兼容微A到全尺寸的USB适配器（从一个评估套件）。显然，答案将是USB协会追逐的恶棍，并阻止他们使用USB标志不符合要求。设计。由于移动制造商是对USB协会最大的贡献者之一，这是不会发生的。



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    Indeed. I have seen a few micro-AB sockets (mostly on evaluation kits) but they seem to have died out.
 
I suspect that mobile phone manufacturers made the pragmatic decision that it was better to not follow the standard than have complaints from ham-fisted punters breaking AB sockets trying to plug B charging cables in upside down, the trapezoidal shape of the micro-B socket making it easier to work out orientation than the rectangular micro-AB.
 
The only time it has been an issue for me was with the Raspberry Pi zero which also used a micro-B socket where it should have been micro-AB, I had to buy a non compliant micro-B to full size USB A socket adapter even though I had a perfectly good compliant micro-A to full size USB A adapter lying around (from an evaluation kit).
 
The obvious answer would be for the USB association to chase the miscreants and stop them using the USB logo for non compliant designs. As the mobile manufacturers are some of the biggest contributors to the USB association it isn't going to happen.

真是胡说八道。现在所有的手机都使用OTG，它可以是一个附加在PC上的用于下载东西的设备，或者你可以把USB记忆棒塞进它，所以手机现在是一个主控器。我有一个32GB的记忆棒，它有一个标准的USB A插座和一个微型USB连接器，另一端只是为了这个目的。电话制造商正在使用正确的连接器。



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What a load of nonsense.
 
All the current model phones use OTG, it can be a device attached to a PC for downloading stuff, or you can plug a USB memory stick into it, so the phone is now acting as a master. I have a 32GB memory stick that has a standard USB A socket one end and a micro-USB connector the other end just for this purpose.
 
The phone manufacturers are using the correct connector.

第3.1.1节是对USB 2规范的MICUSEB规范的现成和嵌入式主机补充和第4.5节。



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Section 3.1.1 of On-The-Go and Embedded Host Supplement and section 4.5 of MicroUSB Specification to the USB 2.0 Specification.