FT2232H_10 Datasheet, PDF(35/63 Page) Future Technology Devices International Ltd. – DUAL HIGH SPEED USB TO MULTIPURPOSE UART/FIFO IC

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FT2232H_10 Datasheet, PDF (35/63 Pages) Future Technology Devices International Ltd. – DUAL HIGH SPEED USB TO MULTIPURPOSE UART/FIFO IC

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Document No.: FT_000061

FT2232H DUAL HIGH SPEED USB TO MULTIPURPOSE UART/FIFO IC

Datasheet Version 2.09

Clearance No.: FTDI#77

4.8.1 Outgoing Fast Serial Data

To send fast serial data out of the FT2232H, the external device must drive the FSCLK clock. If the

FT2232H has data ready to send, it will drive FSDO output low to indicate the start bit. It will not do this

if it is currently receiving data from the external device. This is illustrated in Figure 4.14.

FSCLK

FSDO

0 D0

Start

Bit

D1 D2 D3 D4

D5 D6

Data Bits - LSB first

Figure 4.14 Fast Opto-Isolated Serial Interface Output Data

Notes :-

D7 SRCE

Source

Bit

1. The first bit output (Start bit) is always 0.

2. FSDO is always sent LSB first.

3. The last serial bit output is the source bit (SRCE). It indicates which channel the data has come

from. A â0â means that it has come from Channel A, a â1â means that it has come from Channel B.

4. If the target device is unable to accept the data when it detects the START bit, it should stop the

FSCLK until it can accept the data.

4.8.2 Incoming Fast Serial Data

An external device is allowed to send data into the FT2232H if FSCTS is high. On receipt of a zero START

bit on FSDI, the FT2232H will drop FSCTS on the next positive clock edge. The data from bits 0 to 7 are

then clocked in (LSB first). The last bit (DEST) determines where the data will be written to. The data can

be sent to either channel A or to channel B. If DEST= â0â, the data is sent to channel A, (assuming

channel A is enabled for fast serial mode, otherwise the data is sent to channel B). If DEST= â1â the data

is sent to channel B, (assuming channel B is enabled for fast serial mode, otherwise the data will go to

channel A. (Either channel A, channel B or both channels must be enabled as fast serial mode or the

function is disabled). This is illustrated in Figure 4.15.

FSCTS

FSCLK

FSDI

0 D0

Start

Bit

D1 D2 D3 D4

D5 D6

Data Bits - LSB first

D7 DEST

De stination

Bit

Figure 4.15 Fast Opto-Isolated Serial Interface Input Data

Notes :-

1. The first bit input (Start bit) is always 0.

2. FSDI is always received LSB first.

3. The last received serial bit is the destination bit (DEST).It indicates which channel the data should

go to. A â0â means that it should go to channel A, a â1â means that it should go to channel B.

4. The target device should ensure that CTS is high before it sends data. CTS goes low after data bit

0 (D0) and stays low until the chip can accept more data.

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