UM10503
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© NXP B.V. 2012. All rights reserved.
User manual
Rev. 1.3 — 6 July 2012
997 of 1269
NXP Semiconductors
UM10503
Chapter 38: LPC43xx UART1
UART1 baud rate can be calculated as (n = 1):
(8)
Where PCLK is the peripheral clock, DLM and DLL are the standard UART1 baud rate
divider registers, and DIVADDVAL and MULVAL are UART1 fractional baud rate generator
specific parameters.
The value of MULVAL and DIVADDVAL should comply to the following conditions:
1. 1
MULVAL
15
2. 0
DIVADDVAL
14
3. DIVADDVAL < MULVAL
The value of the FDR should not be modified while transmitting/receiving data or data may
be lost or corrupted.
If the FDR register value does not comply to these two requests, then the fractional divider
output is undefined. If DIVADDVAL is zero then the fractional divider is disabled, and the
clock will not be divided.
38.6.14 UART1 Transmit Enable Register
In addition to being equipped with full hardware flow control (auto-cts and auto-rts
mechanisms described above), TER enables implementation of software flow control, too.
When TxEn=1, UART1 transmitter will keep sending data as long as they are available.
As soon as TxEn becomes 0, UART1 transmission will stop.
describes how to use TxEn bit in order to achieve hardware flow
control, it is strongly suggested to let UART1 hardware implemented auto flow control
features take care of this, and limit the scope of TxEn to software flow control.
TER enables implementation of software and hardware flow control. When TXEn=1,
UART1 transmitter will keep sending data as long as they are available. As soon as TXEn
becomes 0, UART1 transmission will stop.
describes how to use TXEN bit in order to achieve software flow control.
UART1
baudrate
PCLK
16
256
DLM
DLL
+
1
DivAddVal
MulVal
-----------------------------
+
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