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Registers
1180
SPRUH82C – April 2013 – Revised September 2016
Copyright © 2013–2016, Texas Instruments Incorporated
Multichannel Audio Serial Port (McASP)
Table 24-41. Transmitter Status Register (XSTAT) Field Descriptions (continued)
Bit
Field
Value
Description
1
XSYNCERR
Unexpected transmit frame sync flag. XSYNCERR is set when a new transmit frame sync (AFSX)
occurs before it is expected. Causes a transmit interrupt (XINT), if this bit is set and XSYNCERR in
XINTCTL is set. This bit is cleared by writing a 1 to this bit. Writing a 0 has no effect.
0
Unexpected transmit frame sync did not occur.
1
Unexpected transmit frame sync did occur.
0
XUNDRN
Transmitter underrun flag. XUNDRN is set when the transmit serializer is instructed to transfer data
from XBUF to XRSR, but XBUF has not yet been serviced with new data since the last transfer. Causes
a transmit interrupt (XINT), if this bit is set and XUNDRN in XINTCTL is set. This bit is cleared by writing
a 1 to this bit. Writing a 0 has no effect.
0
Transmitter underrun did not occur.
1
Transmitter underrun did occur. See
for details on McASP action upon underrun
conditions.
24.1.34 Current Transmit TDM Time Slot Register (XSLOT)
The current transmit TDM time slot register (XSLOT) indicates the current time slot for the transmit data
frame. The XSLOT is shown in
and described in
Figure 24-67. Current Transmit TDM Time Slot Register (XSLOT)
31
16
Reserved
(A)
R-0
15
9
8
0
Reserved
(A)
XSLOTCNT
R-0
R-17Fh
LEGEND: R = Read only; -
n
= value after reset
A If writing to this field, always write the default value for future device compatibility.
Table 24-42. Current Transmit TDM Time Slot Register (XSLOT) Field Descriptions
Bit
Field
Value
Description
31-9
Reserved
0
Reserved. The reserved bit location always returns the default value. A value written to this field has no
effect. If writing to this field, always write the default value for future device compatibility.
8-0
XSLOTCNT
0-17Fh
Current transmit time slot count. Legal values: 0 to 383 (17Fh). During reset, this counter value is 383
so the next count value, which is used to encode the first DIT group of data, will be 0 and encodes the
B preamble. TDM function is not supported for > 32 time slots. However, TDM time slot counter may
count to 383 when used to transmit a DIT block.