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System Control Registers
439
SLAU723A – October 2017 – Revised October 2018
Copyright © 2017–2018, Texas Instruments Incorporated
System Control
4.2.168 PCEMAC Register (Offset = 0x99C) [reset = 0x1]
Ethernet MAC Power Control (PCEMAC)
The PCEMAC register controls the power applied to the EMAC module. The function of this bit depends
on the current state of the device (run, sleep or deep-sleep mode) and value of the corresponding bits in
the RCGCEMAC, SCGCEMAC, and DCGCEMAC registers. If the Rn, Sn, or Dn bit of the respective
RCGCEMAC, SCGCEMAC, and DCGCEMAC registers is 1 and the device is in that mode, the module is
powered and receives a clock regardless of what the corresponding Pn bit in the PCEMAC register is.
However, if the Rn, Sn, or Dn bit of the respective RCGCEMAC, SCGCEMAC, and DCGCEMAC registers
is 0 and the device is in that mode, then the module behaves differently depending on the value of the
corresponding Pn bit in the PCEMAC register. In this case, when the Pn bit is clear, the module is not
powered and does not receive a clock. If the Pn bit is set, the module is powered but does not receive a
clock.
lists the differences.
Table 4-201. Module Power Control
Rn, Sn, or Dn
Value in
Respective
RCGCx,
SCGCx, or
DCGCx
Register
Pn
Description
0
0
Module is not powered and does not receive a clock. In this case, the state of the peripheral
is not retained.
This is the lowest power consumption state of any peripheral, because it consumes no
dynamic nor leakage current. Hardware should perform a peripheral reset if the active mode
changes and the RCGCx, SCGCx, or DCGCx register is 1 or the P0 bit is changed to 1.
Software must reinitialize the peripheral when reenabled due to the loss of state.
0
1
Module is powered but does not receive a clock.
In this case, the peripheral is inactive. This is the second-lowest power consumption of any
peripheral, because it consumes only leakage current.
1
X
Module is powered and receives a clock.
PCEMAC is shown in
and described in
.
Return to
Figure 4-174. PCEMAC Register
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
RESERVED
R-0x0
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
RESERVED
P0
R-0x0
R/W-
0x1
Table 4-202. PCEMAC Register Field Descriptions
Bit
Field
Type
Reset
Description
31-1
RESERVED
R
0x0
0
P0
R/W
0x1
Ethernet MAC Module 0 Power Contro.l The Pn bit encodings do not
apply if the corresponding bit in the RCGCEMAC, SCGCEMAC, or
DCGCEMAC register is clear.
0x0 = Ethernet MAC Module 0 is not powered and does not receive
a clock. In this case, the state of the module is not retained. This
configuration provides the lowest power consumption state.
0x1 = Ethernet MAC module 0 is powered but does not receive a
clock. In this case, the module is inactive.