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Philips Semiconductors
Volume 1
9.3.12 UART0 Auto-baud Control Register (U0ACR - 0xE000 C020)
The UART0 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.
Table 95:
Bit
0
1
2
7:3
8
9
31:10 -
9.3.13 Auto-baud
The UART0 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).
Two auto-baud measuring modes are available which can be selected by the U0ACR
Mode bit. In mode 0 the baud-rate is measured on two subsequent falling edges of the
UART0 Rx pin (the falling edge of the start bit and the falling edge of the least significant
bit). In mode 1 the baud-rate is measured between the falling edge and the subsequent
rising edge of the UART0 Rx pin (the length of the start bit).
User manual
Auto-baud Control Register (U0ACR - 0xE000 C020) bit description
Symbol
Value Description
Start
This bit is automatically cleared after auto-baud
completion.
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.
Mode
Auto-baud mode select bit.
0
Mode 0.
1
Mode 1.
AutoRestart 0
No restart
1
Restart in case of time-out (counter restarts at next
UART0 Rx falling edge)
-
NA
Reserved, user software should not write ones to
reserved bits. The value read from a reserved bit is not
defined.
ABEOIntClr
End of auto-baud interrupt clear bit (write only
accessible). Writing a 1 will clear the corresponding
interrupt in the U0IIR. Writing a 0 has no impact.
ABTOIntClr
Auto-baud time-out interrupt clear bit (write only
accessible). Writing a 1 will clear the corresponding
interrupt in the U0IIR. Writing a 0 has no impact.
NA
Reserved, user software should not write ones to
reserved bits. The value read from a reserved bit is not
defined.
Rev. 01 — 12 January 2006
UM10161
Chapter 9: UART0
Reset value
0
0
0
0
0
0
0
© Koninklijke Philips Electronics N.V. 2006. All rights reserved.
93
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