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UM10375
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© NXP B.V. 2011. All rights reserved.
User manual
Rev. 3 — 14 June 2011
203 of 368
NXP Semiconductors
UM10375
Chapter 12: LPC13xx UART
12.6.18 UART RS485 Address Match register (U0RS485ADRMATCH - 0x4000
8050)
The U0RS485ADRMATCH register contains the address match value for RS-485/EIA-485
mode.
12.6.19 UART1 RS485 Delay value register (U0RS485DLY - 0x4000 8054)
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.
12.6.20 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.
4
DCTRL
Direction control enable
0
0
Disable Auto Direction Control.
1
Enable Auto Direction Control.
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 212. UART RS485 Control register (U0RS485CTRL - address 0x4000 804C) bit
description
…continued
Bit
Symbol
Value
Description
Reset
value
Table 213. UART RS-485 Address Match register (U0RS485ADRMATCH - address
0x4000 8050) bit description
Bit
Symbol
Description
Reset value
7:0
ADRMATCH
Contains the address match value.
0x00
31:8
-
Reserved
-
Table 214. UART RS-485 Delay value register (U0RS485DLY - address 0x4000 8054) 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
31:8
-
Reserved, user software should not write ones to reserved bits.
The value read from a reserved bit is not defined.
NA