Auto-Baud; User Manual - Philips LPC2101 User Manual

Philips Semiconductors
Volume 1
Table 115: Auto-baud Control Register (U1ACR - 0xE001 0020) bit description
Bit
1
2
7:3
8
9
31:10 -

10.3.15 Auto-baud

The UART1 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 U1DLM and U1DLL
accordingly.
Auto-baud is started by setting the U1ACR Start bit. Auto-baud can be stopped by
clearing the U1ACR 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 U1ACR
Mode bit. In mode 0 the baud-rate is measured on two subsequent falling edges of the
UART1 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 UART1 Rx pin (the length of the start bit).
The U1ACR AutoRestart bit can be used to automatically restart baud-rate measurement
if a time-out occurs (the rate measurement counter overflows). If this bit is set the rate
measurement will restart at the next falling edge of the UART1 Rx pin.
The auto-baud function can generate two interrupts.
The auto-baud interrupts have to be cleared by setting the corresponding U1ACR
ABTOIntClr and ABEOIntEn bits.

User manual

Symbol Value Description
Mode
0
1
AutoRestart 0
1
- NA
ABEOIntClr
ABTOIntClr
NA
•
The U1IIR ABTOInt interrupt will get set if the interrupt is enabled (U1IER ABToIntEn
is set and the auto-baud rate measurement counter overflows).
•
The U1IIR ABEOInt interrupt will get set if the interrupt is enabled (U1IER ABEOIntEn
is set and the auto-baud has completed successfully).
Rev. 01 — 12 January 2006
Auto-baud mode select bit.
Mode 0.
Mode 1.
No restart
Restart in case of time-out (counter restarts at next
UART1 Rx falling edge)
Reserved, user software should not write ones to
reserved bits. The value read from a reserved bit is not
defined.
End of auto-baud interrupt clear bit (write only
accessible). Writing a 1 will clear the corresponding
interrupt in the U1IIR. Writing a 0 has no impact.
Auto-baud time-out interrupt clear bit (write only
accessible). Writing a 1 will clear the corresponding
interrupt in the U1IIR. Writing a 0 has no impact.
Reserved, user software should not write ones to
reserved bits. The value read from a reserved bit is not
defined.
UM10161
Chapter 10: UART1
Reset value
0
0
0
0
0
0
© Koninklijke Philips Electronics N.V. 2006. All rights reserved.
114