Recently, there has been a lot of news about Apple switching to usb-c interface for iPhone next year. It seems that the convenience of one cable is just around the corner. However, do you have any doubt that although they are all usb-c interfaces, they can actually correspond to lightning 4, lightning 3, USB 3.0, USB 4 and other protocols. What is the difference between them?
In fact, we can see a general picture through an official picture:
If it has to be divided into three, six, nine, etc., the lightning 4 certified interface and data line are undoubtedly the Pearl on the crown. It is downward compatible with all previous lightning standards, and can realize the transmission of single line up to 2m, including PCIe, DP, USB data, etc.
Although the bandwidth of thunder 4 is still 40Gbps (bidirectional), the PCIe link can be increased from 16gbps of thunder 3 to 32gbps, and must support dual 4K or 8K display output. It also supports four port thunder docking station, wake-up from sleep and Intel vt-d DMA (direct memory access) protection of virtual machine. Therefore, do not think that thunder 3 to thunder 4 is just a change of vest from bandwidth.
In contrast, USB 3 / DP and USB 4 are much more tolerant than lightning. Running less than 40Gbps can also be called USB 4 (non full function), and the minimum power supply is only 4.5w and 7.5W respectively.
USB history
USB can be traced back to 1996. Its originators include Microsoft, IBM, Intel and so on. The purpose is very simple. It is to promote a common interface. At that time, the starting speed was 1.5mbps, and USB 1.1 was upgraded to 12mbps. In 2001, USB 2.0 bandwidth leaped to 480mbps. 20 years later, USB 2.0 is still active in various fields.
In 2011, USB 3.0 was born in the sky and officially entered the Gigabit era. The initial speed of USB 3.0 reached 5Gbps. In 2014, USB 3.1 came out, of which USB 3.1 Gen2 introduced the type-C interface for the first time, and the speed was increased to 10Gbps. In 2017, USB 3.2 again increased the speed to 20gbps, and the C-Port must be.
However, in 2019, the USB organization launched a new naming mechanism. USB 3.0 / 3.1 was renamed USB 3.2 GEN1 / Gen2, and USB 3.2 was renamed USB 3.2 gen2x2. However, some hardware manufacturers are still used to the previous naming habits.
In the same year, USB 4 was released, which can be said to be civilian lightning 3. The bandwidth was increased to 40Gbps and the power supply was increased to 100W. The introduction of PCIe link and DP1 4A transmission support.
Thunderbolt, Apple Called "Thunderbolt") history
Lightning was jointly developed by Intel and apple. It made its debut in the name of light peak in 2009 and officially launched in 2011. At that time, it was developed based on minidp. At the beginning of the design, it was intended to integrate the mixed output of traditional data and video signals, including the original Daisy chain. The dual channel bandwidth is 20gbps. Two years later, thunderbolt 2 came out and upgraded to support DP1 2 signal transmission, 4K is supported for the first time.
Lightning 3 integrates PCIe 3.0 and dp1.0 2 and USB 3.1 are integrated, supporting 4K 60 / 5K screen and 100W power supply. Based on lightning 3, external graphics card is officially possible.
