Broadcom BCM5722 - Table 478: MII Control Register (Phy_Addr = 0 X1, Reg_Addr = 00 H)

BCM5722 Programmer’s Guide
10/15/07
Broadcom Corporation
Page 415 Transceiver Registers Document 5722-PG101-R
MII CONTROL REGISTER (PHY_ADDR = 0X1, REG_ADDR = 00H)
Table 478: MII Control Register (PHY_Addr = 0x1, Reg_Addr = 00h)
Bit Field Description Init Access
15 Reset To reset the transceiver by software control, a 1 can be
sent to bit 15 of the MII Control Register using an MII write
operation. The bit clears itself after the reset process is
complete and need not be cleared using a second MII
write. Writes to other MII Control Register bits have no
effect until the reset process is completed, which requires
approximately 2.0 µs. Writing a 0 to this bit has no effect.
When this bit is read, it returns a one during the reset
process, otherwise, it returns a 0.
• 1 = PHY reset
• 0 = Normal operation
0R/W
SC
14 Internal Loopback The BCM5722 Ethernet controller can be placed into
internal loopback mode by writing a 1 to bit 14 of the MII
Control Register. The loopback mode can be cleared by
writing a 0 to bit 14 of the MII Control Register, or by
resetting the chip. When this bit is read, it returns a 1
when the chip is in loopback mode, otherwise, it returns
a 0.
• 1 = Loopback mode
• 0 = Normal operation
0R/W
13 Speed Selection (LSB) Bits 6 and 13 of the MII Control Register can be used to
manually select the speed of operation when auto-
negotiation is disabled. When bit 6 is set and bit 13 is
cleared, 1000BASE-T is selected. When bit 6 is cleared
and bit 13 is set, 100BASE-T is selected. When both bits
are cleared, 10BASE-T is selected. Other configurations
are reserved and cause unpredictable behavior in the
BCM5722 Ethernet controller. When read, these bits
return the last value written.
Bits 6,13:
• 1 1 = Reserved
• 1 0 = 1000 Mbps
• 0 1 = 100 Mbps
• 0 0 = 10 Mbps
0R/W
12 Auto-negotiation
Enable
When bit 12 of the MII Control Register is set, the
BCM5722 Ethernet controller mode of operation is
controlled by auto-negotiation. When this bit is cleared,
the BCM5722 Ethernet controller mode of operation is
determined by the manual speed, duplex mode, and
master/slave configuration bits. When this bit is read, it
returns a 1 when auto-negotiation is enabled, otherwise,
it returns a 0.
• 1 = Auto-negotiation enabled
• 0 = Auto-negotiation disabled
1R/W
11 Power Down When bit 11 of the MII Control Register is written to 1, the
transceiver is placed into low-power standby mode.
• 1 = Power down
• 0 = Normal operation.
0R/W