FT201XS-R datasheet(25/49 Pages) FTDI

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FT201X USB I2C SLAVE IC Datasheet

Version 1.4

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

8 Application Examples

The following sections illustrate possible applications of the FT201X. The illustrations have omitted pin

numbers for ease of understanding since the pins differ between the FT201XS and FT201XQ package

options.

8.1 USB to I2C Converter

FT201X

SHIELD

Ferrite

Bead

GND

VCC

GND

VCC

3V3OUT

USBDM

USBDP

VCCIO

VCC

RESET#

100nF

10nF

4.7uF

SDA

SCL

SDA

I2C MASTER DEVICE

VCCIO

27R

GND

47pF

Figure 8.1 Application Example showing USB to I2C Converter

An example of using the FT201X as an I2C peripheral is shown in Figure 8.1. The FT201X is the slave on

the I2C bus.

Therefore the clock supplied to the SCL pin must come from the I2C Master. The device will support

standard I2C data rates such as 100 kbit/s standard mode (SM), 400 kbit/s fast mode (FM), 1 Mbit/s Fast

mode plus (FM+), and 3.4 Mbit/s High Speed mode (HS).

The data line SDA is bi- directional.

The master is initially in master transmit mode by sending a start bit followed by the 7-bit address of the

slave it wishes to communicate with, which is finally followed by a single bit representing whether it

wishes to write(0) to or read(1) from the slave.

If the slave (FT201X) exists on the bus then it will respond with an ACK bit (active low for acknowledged)

for that address. The master then continues in either transmit or receive mode (according to the

read/write bit it sent), and the slave continues in its complementary mode (receive or transmit,

respectively).

The address and the data bytes are sent most significant bit first. The start bit is indicated by a high-to-

low transition of SDA with SCL high; the stop bit is indicated by a low-to-high transition of SDA with SCL

high.

If the master wishes to write to the slave then it repeatedly sends a byte with the slave sending an ACK

bit. (In this situation, the master is in master transmit mode and the slave is in slave receive mode.)

If the master wishes to read from the slave then it repeatedly receives a byte from the slave, the master

sending an ACK bit after every byte but the last one. (In this situation, the master is in master receive

mode and the slave is in slave transmit mode.)

The master then ends transmission with a stop bit, or it may send another START bit if it wishes to retain

control of the bus for another transfer (a "combined message").

I²C defines three basic types of message, each of which begins with a START and ends with a STOP:



Single message where a master writes data to a slave;

FT201XS-R 数据表(PDF) 25 Page - Future Technology Devices International Ltd.

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