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UM10360_0
© NXP B.V. 2009. All rights reserved.
User manual
Rev. 00.06 — 5 June 2009
313 of 808
NXP Semiconductors
UM10360
Chapter 15: LPC17xx UART1
4.19 UART1 RS-485 Address Match register (U1RS485ADRMATCH -
0x4001 0050)
The U1RS485ADRMATCH register contains the address match value for RS-485/EIA-485
mode.
4.20 UART1 RS-485 Delay value register (U1RS485DLY - 0x4001 0054)
The user may program the 8-bit RS485DLY register with a delay between the last stop bit
leaving the TXFIFO and the de-assertion of RTS (or DTR). This delay time is in periods of
the baud clock. Any delay time from 0 to 255 bit times may be programmed.
4.21 RS-485/EIA-485 modes of operation
The RS-485/EIA-485 feature allows the UART to be configured as an addressable slave.
The addressable slave is one of multiple slaves controlled by a single master.
The UART master transmitter will identify an address character by setting the parity (9th)
bit to ‘1’. For data characters, the parity bit is set to ‘0’.
Each UART slave receiver can be assigned a unique address. The slave can be
programmed to either manually or automatically reject data following an address which is
not theirs.
5
OINV
This bit reverses the polarity of the direction
control signal on the RTS (or DTR) pin.
0
0
The direction control pin will be driven to logic ‘0’
when the transmitter has data to be sent. It will be
driven to logic ‘1’ after the last bit of data has been
transmitted.
1
The direction control pin will be driven to logic ‘1’
when the transmitter has data to be sent. It will be
driven to logic ‘0’ after the last bit of data has been
transmitted.
31:6 -
-
Reserved, user software should not write ones to
reserved bits. The value read from a reserved bit
is not defined.
NA
Table 287: UART1 RS485 Control register (U1RS485CTRL - address 0x4001 004C) bit
description
Bit
Symbol
Value
Description
Reset
value
Table 288. UART1 RS-485 Address Match register (U1RS485ADRMATCH - address
0x4001 0050) bit description
Bit
Symbol
Description
Reset value
7:0
ADRMATCH
Contains the address match value.
0x00
Table 289. UART1 RS-485 Delay value register (U1RS485DLY - address 0x4001 00454) bit
description
Bit
Symbol
Description
Reset value
7:0
DLY
Contains the direction control (RTS or DTR) delay
value. This register works in conjunction with an 8-bit
counter.
0x00