1000字范文 > FTDI通用转USB芯片简述

FTDI通用转USB芯片简述

时间：2018-08-22 06:50:05

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FTDI通用转USB芯片简述

FTDI公司的FT2232系列芯片可实现USB与异步串行口RS232/RS485、同步串行总线IIC/SPI/JTAG相互通信，市场占有率，使用普遍。

FTDI芯片有两种类型的驱动：virtual COM port driver (VCP)和D2xx。VCP就是常用的U转串COM驱动，实现USB到虚拟串口功能，应用于异步RS232/RS485与USB间通信，linux设备文件为/dev/ttyUSBx；D2XX应用于同步串行总线IIC/SPI/JTAG与USB间通信，整个驱动框架都有FTDI公司提供。

COM驱动

linux支持FTDI公司的VCP驱动需配置内核：

Device Drivers --->[*] USB support ---><M> USB Serial Converter support ---><M> USB Prolific 2303 Single Port Serial Driver<M> USB FTDI Single Port Serial Driver

Prolific和FTDI是常用的USB转串口芯片厂商。通用模块usbserial.ko，prolific公司的模块pl2303.ko，ftdi公司的模块ftdi_sio.ko

[ 1.771996] usbcore: registered new interface driver usbfs[ 1.777600] usbcore: registered new interface driver hub[ 1.782975] usbcore: registered new device driver usb[ 3.227325] usbcore: registered new interface driver usb-storage[ 3.331190] usbcore: registered new interface driver bcm203x[ 3.336872] usbcore: registered new interface driver bfusb[ 3.342381] usbcore: registered new interface driver btusb[ 3.347893] usbcore: registered new interface driver ath3k[ 3.496381] usbcore: registered new interface driver usbhid[ 3.501958] usbhid: USB HID core driver[ 58.132670] usb 1-1: new full-speed USB device number 2 using xhci-hcd[ 58.314580] usbcore: registered new interface driver usbserial[ 58.316675] usbcore: registered new interface driver pl2303[ 58.316707] usbserial: USB Serial support registered for pl2303[ 58.317386] usb 1-1: pl2303 converter now attached to ttyUSB0[ 289.400405] usb 1-1: USB disconnect, device number 2

或

[ 1.774779] usbcore: registered new interface driver usbfs[ 1.780377] usbcore: registered new interface driver hub[ 1.785752] usbcore: registered new device driver usb[ 3.230535] usbcore: registered new interface driver usb-storage[ 3.334244] usbcore: registered new interface driver bcm203x[ 3.339930] usbcore: registered new interface driver bfusb[ 3.345439] usbcore: registered new interface driver btusb[ 3.350951] usbcore: registered new interface driver ath3k[ 3.495753] usbcore: registered new interface driver usbhid[ 3.501362] usbhid: USB HID core driver[ 3.643788] usb 1-1: new high-speed USB device number 2 using xhci-hcd[ 7.070296] usbcore: registered new interface driver usbserial[ 7.099899] usbcore: registered new interface driver ftdi_sio[ 7.099925] usbserial: USB Serial support registered for FTDI USB Serial Device[ 7.100046] usb 1-1: Detected FT2232H[ 7.100439] usb 1-1: FTDI USB Serial Device converter now attached to ttyUSB0[ 7.100539] usb 1-1: Detected FT2232H[ 7.100667] usb 1-1: FTDI USB Serial Device converter now attached to ttyUSB1[ 86.423288] usb 1-1: USB disconnect, device number 2

插入USB设备会在/dev/ttyUSBx文件出现，可像操作普通的串口文件/dev/ttySx一样操作，采用通用termios编程。

D2XX驱动

在linux中VCP和D2XX驱动是不兼容的，当D2XX驱动应用前应卸载VCP驱动模块：

sudo rmmod ftdi_sio

sudo rmmod usbserial

实际测试中采用D2XX驱动时系统会自动卸载VCP驱动。

D2XX驱动协议栈如下图，D2XX驱动libftd2xx.tar.gz可在如下页面下载：/Drivers/D2XX.htm，或者直接在系统下apt安装（可能需要libusb-dev）：

apt install libftdi-dev

在D2XX驱动之上是libmpsse，即MPSSE库。Multi Protocol Synchronous Serial Engine(MPSSE)是一个通用的同步总线如I2C、SPI或JTAG通信库，用于FT2232D、FT2232H、FT4232H和FT232H芯片通过USB与PC或ARM通信。MPSSE基于D2XX设计。