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UM10503
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User manual
Rev. 2.1 — 10 December 2015
1139 of 1441
NXP Semiconductors
UM10503
Chapter 40: LPC43xx/LPC43Sxx USART0_2_3
40.6.18 USART RS485 Delay value register
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 the DIR pin. This delay time is in periods of
the baud clock. Any delay time from 0 to 255 bit times may be programmed.
40.6.19 USART Synchronous mode control register
SYNCCTRL register is a Read/write register that controls the synchronous mode. The
synchronous mode control module generates or receives the synchronous clock with the
serial input/ output data and distributes the edge detect samples to the transmit and
receive shift registers.
Table 945. USART RS485 Delay value register (RS485DLY, addresses 0x4008 1054 (USART0),
0x400C 1054 (USART2), 0x400C 2054 (USART3)) bit description
Bit
Symbol
Description
Reset value
7:0
DLY
Contains the direction control 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
Table 946. USART Synchronous mode control registers (SYNCCTRL, address addresses
0x4008 1058 (USART0), 0x400C 1058 (USART2), 0x400C 2058 (USART3)) bit
description
Bit
Symbol
Value
Description
Reset
value
0
SYNC
Enables synchronous mode.
0
0
Disabled.
1
Enabled.
1
CSRC
Clock source select.
0
0
Slave mode. Synchronous slave mode (SCLK in)
1
Master mode. Synchronous master mode (SCLK out)
2
FES
Edge sampling.
0
0
Rising. RxD is sampled on the rising edge of SCLK.
1
Falling. RxD is sampled on the falling edge of SCLK.
3
TSBYPASS
Transmit synchronization bypass in synchronous slave
mode.
0
0
Synchronized. The input clock is synchronized prior to
being used in clock edge detection logic.
1
Not synchronized. The input clock is not synchronized
prior to being used in clock edge detection logic. This
allows for a high er input clock rate at the expense of
potential metastability.
4
CSCEN
Continuous master clock enable (used only when
CSRC is 1)
0
0
On character. SCLK cycles only when characters are
being sent on TxD.
1
Continuously. SCLK runs continuously (characters can
be received on RxD independently from transmission on
TxD).