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MDIO Registers
4.2
MDIO Control Register (CONTROL)
The MDIO control register (CONTROL) is shown in
Figure 26
and described in
Table 24
.
Figure 26. MDIO Control Register (CONTROL)
31
30
29
28
24
23
21
20
19
18
17
16
IDLE
ENABLE
Rsvd
HIGHEST_USER_CHANNEL
Reserved
PREAMBLE
FAULT
FAULTENB
Reserved
R-1
R/W-0
R-0
R-1
R-0
R/W-0
R/W1C-0
R/W-0
R-0
15
0
CLKDIV
R/W-FFh
LEGEND: R/W = Read/Write; R = Read only; W1C = Write 1 to clear (writing a 0 has no effect); -n = value after reset
Table 24. MDIO Control Register (CONTROL) Field Descriptions
Bit
Field
Value
Description
31
IDLE
State machine IDLE status bit.
0
State machine is not in idle state.
1
State machine is in idle state.
30
ENABLE
State machine enable control bit. If the MDIO state machine is active at the time it is
disabled, it will complete the current operation before halting and setting the idle bit.
0
Disables the MDIO state machine.
1
Enable the MDIO state machine.
29
Reserved
0
Reserved
28-24
HIGHEST_USER_CHANNEL
0-1Fh
Highest user channel that is available in the module. It is currently set to 1. This
implies that MDIOUserAccess1 is the highest available user access channel.
23-21
Reserved
0
Reserved
20
PREAMBLE
Preamble disable
0
Standard MDIO preamble is used.
1
Disables this device from sending MDIO frame preambles.
19
FAULT
Fault indicator. This bit is set to 1 if the MDIO pins fail to read back what the device
is driving onto them. This indicates a physical layer fault and the module state
machine is reset. Writing a 1 to this bit clears this bit, writing a 0 has no effect.
0
No failure
1
Physical layer fault; the MDIO state machine is reset.
18
FAULTENB
Fault detect enable. This bit has to be set to 1 to enable the physical layer fault
detection.
0
Disables the physical layer fault detection.
1
Enables the physical layer fault detection.
17-16
Reserved
0
Reserved
15-0
CLKDIV
0-FFFFh
Clock Divider bits. This field specifies the division ratio between the peripheral clock
and the frequency of MDIO_CLK. MDIO_CLK is disabled when CLKDIV is cleared to
0. MDIO_CLK frequency = peripheral clock frequency/( 1).
71
SPRUFL5B – April 2011
EMAC/MDIO Module
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