McASP Registers
22.4.1.37 Serializer Control Registers (SRCTLn)
Each serializer on the McASP has a serializer control register (SRCTL). There are up to 6 serializers per
McASP. The SRCTL is shown in
and described in
.
NOTE:
Device-specific registers
Accessing SRCTLn not implemented on a specific device may cause improper device
operation.
Figure 22-75. Serializer Control Registers (SRCTLn)
31
16
Reserved
R-0
15
6
5
4
3
2
1
0
Reserved
RRDY
XRDY
DISMOD
SRMOD
R-0
R-0
R-0
R/W-0
R/W-0
LEGEND: R/W = Read/Write; R = Read only; -n = value after reset
Table 22-48. Serializer Control Registers (SRCTLn) Field Descriptions
Bit
Field
Value
Description
31-6
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.
5
RRDY
Receive buffer ready bit. RRDY indicates the current receive buffer state. Always reads 0 when
programmed as a transmitter or as inactive. If SRMOD bit is set to receive (2h), RRDY switches from 0
to 1 whenever data is transferred from XRSR to RBUF.
0
Receive buffer (RBUF) is empty.
1
Receive buffer (RBUF) contains data and needs to be read before the start of the next time slot or a
receiver overrun occurs.
4
XRDY
Transmit buffer ready bit. XRDY indicates the current transmit buffer state. Always reads 0 when
programmed as a receiver or as inactive. If SRMOD bit is set to transmit (1h), XRDY switches from 0 to
1 when XSRCLR in GBLCTL is switched from 0 to 1 to indicate an empty transmitter. XRDY remains
set until XSRCLR is forced to 0, data is written to the corresponding transmit buffer, or SRMOD bit is
changed to receive (2h) or inactive (0).
0
Transmit buffer (XBUF) contains data.
1
Transmit buffer (XBUF) is empty and needs to be written before the start of the next time slot or a
transmit underrun occurs.
3-2
DISMOD
0-3h
Serializer pin drive mode bit. Drive on pin when in inactive TDM slot of transmit mode or when serializer
is inactive. This field only applies if the pin is configured as a McASP pin (PFUNC = 0).
0
Drive on pin is 3-state.
1h
Reserved.
2h
Drive on pin is logic low.
3h
Drive on pin is logic high.
1-0
SRMOD
0-3h
Serializer mode bit.
0
Serializer is inactive.
1h
Serializer is transmitter.
2h
Serializer is receiver.
3h
Reserved.
3874
Multichannel Audio Serial Port (McASP)
SPRUH73H – October 2011 – Revised April 2013
Copyright © 2011–2013, Texas Instruments Incorporated