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4.3 MDIO Control Register (CONTROL)
The MDIO control register (CONTROL) is shown in Figure 30 and described in Table 23.
Figure 30. MDIO Control Register (CONTROL)
31 30 29 28 24 23 21 20 19 18 17 16
FAULT
IDLE ENABLE Reserved HIGHEST_USER_CHANNEL Reserved PREAMBLE FAULT Reserved
ENB
R-1 R/W-0 R-0 R-1 R-0 R/W-0 R/WC-0 R/W-0 R-0
15 0
CLKDIV
R/W-255
LEGEND: R/W = Read/Write; R = Read only; -n = value after reset
Table 23. 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 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.
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 Clock Divider bits. This field specifies the division ratio between peripheral bus
peripheral clock and the frequency of MDCLK. MDCLK is disabled when CLKDIV is
set to 0. MDCLK frequency = peripheral clock frequency/(CLKDIV + 1).
78
C6472/TCI6486 EMAC/MDIO SPRUEF8F–March 2006–Revised November 2010
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