Datasheet

UM10398 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2014. All rights reserved.
User manual Rev. 12.3 — 10 June 2014 212 of 547
NXP Semiconductors
UM10398
Chapter 13: LPC111x/LPC11Cxx UART
13.5.12 UART Auto-baud Control Register (U0ACR - 0x4000 8020)
The UART Auto-baud Control Register (U0ACR) controls the process of measuring the
incoming clock/data rate for the baud rate generation and can be read and written at
user’s discretion.
13.5.13 Auto-baud
The UART auto-baud function can be used to measure the incoming baud rate based on
the ”AT" protocol (Hayes command). If enabled the auto-baud feature will measure the bit
time of the receive data stream and set the divisor latch registers U0DLM and U0DLL
accordingly.
Auto-baud is started by setting the U0ACR Start bit. Auto-baud can be stopped by clearing
the U0ACR Start bit. The Start bit will clear once auto-baud has finished and reading the
bit will return the status of auto-baud (pending/finished).
Table 199. Auto baud Control Register (U0ACR - address 0x4000 8020) bit description
Bit Symbol Value Description Reset
value
0 START Start bit. This bit is automatically cleared after
auto-baud completion.
0
0 Auto-baud stop (auto-baud is not running).
1 Auto-baud start (auto-baud is running). Auto-baud
run bit. This bit is automatically cleared after
auto-baud completion.
1 MODE Auto-baud mode select 0
0 Mode 0.
1 Mode 1.
2 AUTORESTART Restart enable 0
0 No restart
1 Restart in case of time-out (counter restarts at next
UART Rx falling edge)
0
7:3 - Reserved, user software should not write ones to
reserved bits. The value read from a reserved bit is
not defined.
0
8 ABEOINTCLR End of auto-baud interrupt clear (write only
accessible)
0
0 Writing a 0 has no impact.
1 Writing a 1 will clear the corresponding interrupt in
the U0IIR.
9 ABTOINTCLR Auto-baud time-out interrupt clear (write only
accessible)
0
0 Writing a 0 has no impact.
1 Writing a 1 will clear the corresponding interrupt in
the U0IIR.
31:10 - Reserved, user software should not write ones to
reserved bits. The value read from a reserved bit is
not defined.
0