FT201XS-R datasheet(29/49 Pages) FTDI

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FT201X USB I2C SLAVE IC Datasheet

Version 1.4

Document No.: FT_000627 Clearance No.: FTDI# 264

9 USB and I2C Interfacing

This section covers the transfer of data from USB to I2C and vice versa.

Please note that the FT200XD and FT201X are I2C slave devices only and should be interfaced to an I2C

host (often in a microcontroller or FPGA). If an I2C master is required, please see the FT232H, FT2232H,

FT4232H and FT2232D devices.

This section covers transfer of data only. The USB and I2C interfaces on the FT200XD and FT201X can

also be used for programming of the MTP memory, which is covered in a separate section.

Throughout this section, the reference FT-X applies to the FT200XD and FT201X devices, as the other

members of the FT-X family do not have I2C interfaces.

9.1 Host Interface (USB)

From the host computer’s point of view, the I2C data can be sent and received in the same way as when

interfacing to one of the standard UART devices such as the FT232R. The FT-X handles the entire I2C

protocol inside the chip and so reading and writing data does not require any special programming from

the PC side. It can be treated as a simple data bridge.

9.1.1 VCP and D2xx Interfaces

Like the other FTDI devices, the host can use D2xx commands or can use a Virtual COM Port (VCP) to

communicate with the device.

D2xx Interface

The D2xx method allows the application software to use the functions in the FTDI D2xx library to

communicate directly with the device. This is a library provided free-of-charge by FTDI and is available

within the driver download files at the link below.

http://www.ftdichip.com/Drivers/D2XX.htm

It includes functions to find the FTDI devices on the system, open a particular device, send data to the

device and read data from the device. Any data written using FT_Write, for example, will be sent to the

FT-X chip and will be available for the external I2C Master to read. As mentioned above, only the data

itself needs to be sent as the FT-X handles all of the I2C specific protocol.

There are many other functions available, and full details can be found in the D2xx Programmers Guide.

http://www.ftdichip.com/Support/Documents/ProgramGuides/D2XX_Programmer's_Guide(FT_000071).pd

Virtual COM Port Interface

If using the Virtual Com Port (VCP), the device will appear as if it were a real COM port on the computer.

This is useful where an application has already been written to use an RS232 port on the computer as it

allows that application to treat the FT-X as if it were a real COM port. This port can be opened in a

terminal program or a custom application in the same way as a serial port would be opened. Data can

then be sent or received using standard serial / COM port functions.

No I2C decoding is required as the chip itself handles the I2C protocol. Because of this, even I2C versions

of the FT-X family can be used with the VCP interface. Any data which the host PC sends to the Virtual

COM Port (for example, typed into the terminal window in HyperTerminal) will be sent over USB to the

FT-X and can then be read by the external I2C Master. Likewise, any data written to the FT-X over I2C will

be sent to the PC where the terminal program will display it.

Since the FT-X is the I2C slave and does not generate a clock signal, the settings such as baud rate and

handshaking do not have any effect.

FT201XS-R 数据表(PDF) 29 Page - Future Technology Devices International Ltd.

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