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4.2
MDIO Control Register (CONTROL)
MDIO Registers
The MDIO control register (CONTROL) is shown in
Figure 28
and described in
Table 26
.
Figure 28. 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 = R = Read only; R/W = Read/Write; W1C = Write 1 to clear, write of 0 has no effect; -
n
= value after reset
Table 26. 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 it 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 MDCLK. MDCLK is disabled when CLKDIV is set to
0. MDCLK frequency = peripheral clock frequency/( 1).
72
Ethernet Media Access Controller (EMAC)/Management Data Input/Output (MDIO)
SPRUEQ6 – December 2007
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