UART Registers
19.5.1.26 Auxiliary Control Register (ACREG)
The auxiliary control register (ACREG) is shown in
and described in
.
NOTE:
•
If transmit FIFO is not empty and MDR1[5] = 1, IrDA starts a new transfer with data of
previous frame as soon as abort frame has been sent. Therefore, TX FIFO must be
reset before sending an abort frame.
•
It is recommended to disable TX FIFO underrun capability by masking corresponding
underrun interrupt. When disabling underrun by setting ACREG[4] = 1, unknown data is
sent over TX line.
Figure 19-59. Auxiliary Control Register (ACREG)
15
8
Reserved
R-0
7
6
5
4
3
2
1
0
PULSETYPE
SDMOD
DISIRRX
DISTXUNDERRUN
SENDSIP
SCTXEN
ABORTEN
EOTEN
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
LEGEND: R/W = Read/Write; R = Read only; -n = value after reset
Table 19-57. Auxiliary Control Register (ACREG) Field Descriptions
Bit
Field
Value
Description
15-8
Reserved
0
Reserved.
7
PULSETYPE
SIR pulse-width select:
0
3/16 of baud-rate pulse width
1
1.6
μ
s
6
SDMOD
Primary output used to configure transceivers. Connected to the SD/MODE input pin of IrDA
transceivers.
0
SD pin is set to high.
1
SD pin is set to low.
5
DISIRRX
Disable RX input.
0
Normal operation (RX input automatically disabled during transmit, but enabled outside of
transmit operation).
1
Disables RX input (permanent state; independent of transmit).
4
DISTXUNDERRUN
Disable TX underrun.
0
Long stop bits cannot be transmitted. TX underrun is enabled.
1
Long stop bits can be transmitted.
3
SENDSIP
MIR/FIR modes only. Send serial infrared interaction pulse (SIP).
If this bit is set during an MIR/FIR transmission, the SIP is sent at the end of it. This bit is
automatically cleared at the end of the SIP transmission.
0
No action.
1
Send SIP pulse.
2
SCTXEN
Store and control TX start. When MDR1[5] = 1 and the LH writes 1 to this bit, the TX state-
machine starts frame transmission. This bit is self-clearing.
1
ABORTEN
Frame abort. The LH can intentionally abort transmission of a frame by writing 1 to this bit.
Neither the end flag nor the CRC bits are appended to the frame.
0
EOTEN
EOT (end-of-transmission) bit. The LH writes 1 to this bit just before it writes the last byte to the
TX FIFO in the set-EOT bit frame-closing method. This bit is automatically cleared when the LH
writes to the THR (TX FIFO).
3528
Universal Asynchronous Receiver/Transmitter (UART)
SPRUH73H – October 2011 – Revised April 2013
Copyright © 2011–2013, Texas Instruments Incorporated