10/100 Non-PCI Ethernet Single Chip MAC + PHY
Datasheet
Chapter 9 PHY MII Registers
Multiple Register Access
Multiple registers can be accessed on a single PHY Ml serial port access cycle with the multiple
register access features. The multiple register access features can be enabled by setting the multiple
register access enables bit in the PHY Ml serial port Configuration 2 register. When multiple register
access is enabled, multiple registers can be accessed on a single PHY Ml serial port access cycle by
setting the register address to 11111 during the first 16 MDC clock cycles. There is no actual register
residing in register address location 11111, so when the register address is then set to 11111, all eleven
registers are accessed on the 176 rising edges of MDC that occur after the first 16 MDC clock cycles
of the PHY Ml serial port access cycle. The registers are accessed in numerical order from 0 to 20.
After all 192 MDC clocks have been completed, all the registers have been read/written, and the serial
shift process is halted, data is latched into the device, and MDIO goes into high impedance state.
Another serial shift cycle cannot be initiated until the idle condition (at least 32 continuous 1's) is
detected.
Bit Types
Since the serial port is bi-directional, there are many types of bits. Write bits (W) are inputs during a
write cycle and are high impedance during a read cycle. Read bits (R) are outputs during a read cycle
and high impedance during a write cycle. Read/Write bits (RW) are actually write bits, which can be
read out during a read cycle. R/WSC bits are R/W bits that are self-clearing after a set period of time
or after a specific event has completed. R/LL bits are read bits that latch themselves when they go
low, and they stay latched low until read. After they are read, they are reset high. R/LH bits are the
same as R/LL bits except that they latch high. R/LT are read bits that latch themselves whenever they
make a transition or change value, and they stay latched until they are read. After R/LT bits are read,
they are updated to their current value. R/LT bits can also be programmed to assert the interrupt
function.
Bit Type Definition
R:
Read Only
R/WSC Read/Write
:
Self Clearing
W:
Write Only
R/LH:
Read/Latch
high
RW:
R/LT:
Read/Write
R/LL:
Read/Latch
low
Read/Latch on Transition
REGISTER ADDRESS
REGISTER NAME
0
1
Control
Status
2,3
4
PHY ID
Auto-Negotiation Advertisement
Auto-Negotiation Remote End Capability
Reserved
5
6....15
16
Configuration 1
SMSC LAN91C111-REV B
Revision 1.8 (07-13-05)
DATA8S1HEET
SMSC [ SMSC CORPORATION ]
