FT201XQ-R datasheet(33/49 Pages) FTDI

33 / 49 page

FT201X USB I2C SLAVE IC Datasheet

Version 1.4

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

how many bytes are available. This signal can be mapped to the CBUS pins. Note that the

Receive buffer is the buffer which holds data which has come from the external I2C master and is

going to the host computer over USB.

Do a write over I2C (Master transmitter, Slave receiver) and check if the FT-X ACKs. The FT-X will

NAK if there is no space in the buffer for the data to be written into. The FT-X will NACK in the

address phase if this is the first byte being written and there is no space available. If the buffer

becomes full during a burst write, the FT-X will NACK any bytes during the data phase which

cannot be accommodated in the buffer.

Note that because the acknowledgement can be checked for each byte written (since the FT-X slave is

generating the acknowledge when writing to it), there is no command to ask the FT-X how much buffer

space is available.

9.3 Other I2C Commands

Soft reset

This uses the General Call Address. If the second byte is 0x06 (0000 0110) it will be interpreted by the

FT-X as the Soft Reset command. This will reset the chip and clear all buffers.

Flush command

This uses the General Call Address. If the second byte is 0x0E (0000 1110) it will be interpreted by the

FT-X as the Flush command and the Transmit and Receive buffers will be flushed of all data.

Figure 9.4: Flush data command

Read Data Available command

This uses the General Call Address. If the second byte is 0x0C (0000 1100) it will be interpreted by the

block as the Read Data Available command and on the next I2C read cycle following this command, the

data will hold the number of bytes available for burst read.

Figure 9.5: Reading the amount of data available

USB State command

This uses the General Call Address. If the second byte is 0x16 (0001 0110) it will be interpreted by the

block as the USB State command and on the next read cycle following this command, the data will hold

the coded USB State value. The USB state allows you to check the current USB enumeration state:

0x00 = Suspended.

0x01 = Default.

0x02 = Addressed.

0x03 = Configured.

Note: The Configured state is the normal operating state.

FT201XQ-R 데이터시트(PDF) 33 Page - Future Technology Devices International Ltd.