FT2232HQ-REEL FTDI, FT2232HQ-REEL Datasheet - Page 23

• Manufacturer Part Number: FT2232HQ-REEL
• Description: USB Interface IC USB HS to Dual UART/ FIFO/SPI/JTAG/I2C
• Manufacturer: FTDI

Specifications of FT2232HQ-REEL

• Mounting Style: SMD/SMT
• Package / Case: QFN
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Document No.: FT_000061
FT2232H DUAL HIGH SPEED USB TO MULTIPURPOSE UART/FIFO IC
Datasheet Version 2.10
Clearance No.: FTDI#77
4.3.3 Dual Port RS485 Configuration
Figure 4.3 illustrates how the FT2232H can be configured as a dual RS485 interface.
Figure 4.3 Dual RS485 Configuration
In this case both channel A and channel B are configured as RS485 operating at TTL levels and a level
converter device (half duplex RS485 transceiver) is used to convert the TTL level signals from the
FT232H to RS485 levels. It has separate enables on both the transmitter and receiver. With RS485, the
transmitter is only enabled when a character is being transmitted from the UART. The TXDEN pins on the
FT2232H are provided for exactly that purpose, and so the transmitter enables are wired to the TXDEN‟s.
The receiver enable is active low, so it is wired to the PWREN# pin to disable the receiver when in USB
suspend mode.
RS485 is a multi-drop network – i.e. many devices can communicate with each other over a single two
wire cable connection. The RS485 cable requires to be terminated at each end of the cable. Links are
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