USB Type-C插座连接到多路复用器时，MUXSEL线可通过FX3的GPIO输出来控制，请问选择IO口有什么要求吗，以及选定的这个IO口在Fx3程序中该怎么配置？

[chme_4259176]

主要是想了解在程序中IO口该如何进行配置

[YangyangC_06 · Accepted solution]

你可以参考如下的步骤（就不翻译了）

1. After the FX3 device gets connected to a Type-C host, the FX3 device gets powered.
2. Once powered, the firmware starts running inside FX3.
3. Configure the GPIO as an output that is used as a MUXSEL line.
4. Before the USB connect, the USB2.0 PHY is disabled in the firmware.
5. Then, the firmware attempts a USB 3.0 connection.
6. If it finds the terminations, it will enumerate as a SuperSpeed device.
7. If it does not find a termination. It will enable a USB2.0 PHY.
8. Then the MUXSEL GPIO is toggled by FX3 in order to change the Mux switch position.
9. Again, the firmware attempts a USB3.0 connection/.
10. If it is a USB 3.0 device, it will enumerate as a USB 3.0 device or else it will enumerate as a USB 2.0 device.

The code snippet snapshot for the above mentioned flowchart is as under: