并且会在/dev/input 目录下生成一个名为 eventX(X=0,1,2,3…)的文件,这个就是前面讲的输入子系统,鼠标和键盘都是作为输入子系统设备。 如果要测试 USB 键盘,可以将 LCD 作为默认终端控制台,在开发板的 /etc/inittab 中添加以下语句: tty1::askfirst:-/bin/sh 然后就可以使用开发板屏幕作为终端控制,使用...
具体阻值是要根据驱动器的输出阻抗来决定 tune2 HS output current to increase Vlogic_high level + HSTX slew-rate slew-rate应该是影响眼图的斜率,tune1 + tune2 + tune4 结合可以调整眼图的质量,增加usb的驱动能力 tune3 Receiver sensitivity, adjust the squelch threshold to compensate for a USB bus ...
ver 5.1 • Beacon transmission and reception • Selectable Tx Margining, Tx De-emphasis and signal swing values • Lane Margining at the Receiver • Polarity • Electrical Idle Entry/Exit Detection (Squelch) 2.2 USB PHY Layer The USB PHY Layer handles the low...
2. Squelch detection following USB reset with a successful HS handshake [HS handshake is declared to be successful after single chirp J chirp K pair where each chirp is within 18 μs – 128 μs]. Ground 1.8-V LDO output. Only enabled when operating in High Speed mode. Requires 0.1-µ...
Since the INT_N pin is open-drain during normal function, selecting the secondary REFCLK frequencies requires that the INT_N pin be driven low from an external source during Hub.Init and then, after startup, that external source must turn into an input to receive the INT_N signal. Table ...
文本说明硬件数据手册imx6usb certification guide.pdf,Freescale Semiconductor, Inc. Document Number: IMXUSBCGUG Users Guide Rev. 0 10/2015 , i.MX 6 Series USB Certification Guide 1. Introduction Contents The purpose of this document is to describe how to 1
transmission and reception • Selectable Tx margining, Tx de-emphasis and signal swing values • Lane margining at the receiver • Polarity (original PIPE) • Electrical Idle entry and exit detection (Squelch) 2.2 USB PHY Layer The USB PHY layer handles the low-level USB protocol and ...