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Registers
1141
SPRUH82C – April 2013 – Revised September 2016
Copyright © 2013–2016, Texas Instruments Incorporated
Multichannel Audio Serial Port (McASP)
24.1.4 Pin Direction Register (PDIR)
The pin direction register (PDIR) specifies the direction of AXR[n], ACLKX, AHCLKX, AFSX, ACLKR,
AHCLKR, and AFSR pins as either an input or an output pin. The PDIR is shown in
and
described in
Regardless of the pin function register (PFUNC) setting, each PDIR bit must be set to 1 for the specified
pin to be enabled as an output and each PDIR bit must be cleared to 0 for the specified pin to be an input.
For example, if the McASP is configured to use an internally-generated bit clock and the clock is to be
driven out to the system, the PFUNC bit must be cleared to 0 (McASP function) and the PDIR bit must be
set to 1 (an output).
When AXR[n] is configured to transmit, the PFUNC bit must be cleared to 0 (McASP function) and the
PDIR bit must be set to 1 (an output). Similarly, when AXR[n] is configured to receive, the PFUNC bit must
be cleared to 0 (McASP function) and the PDIR bit must be cleared to 0 (an input).
CAUTION
Writing to Reserved Bits
Writing a value other than 0 to reserved bits in this register may cause improper
device operation.
Figure 24-37. Pin Direction Register (PDIR)
31
30
29
28
27
26
25
24
AFSR
AHCLKR
ACLKR
AFSX
AHCLKX
ACLKX
AMUTE
Reserved
(A)
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R-0
23
16
Reserved
(A)
R-0
15
14
13
12
11
10
9
8
AXR15
AXR14
AXR13
AXR12
AXR11
AXR10
AXR9
AXR8
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
7
6
5
4
3
2
1
0
AXR7
AXR6
AXR5
AXR4
AXR3
AXR2
AXR1
AXR0
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
A If writing to this field, always write the default value for future device compatibility.