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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/(CLKDIV + 1).
71
SPRUFL5B–April 2011 EMAC/MDIO Module
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