DM385, DM388
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SPRS821D –MARCH 2013–REVISED DECEMBER 2013
8.6.3 Management Data Input/Output (MDIO)
The Management Data Input/Output (MDIO) module continuously polls all 32 MDIO addresses in order to
enumerate all PHY devices in the system.
The MDIO module implements the 802.3 serial management interface to interrogate and control Ethernet
PHYs using a shared two-wire bus. Host software uses the MDIO module to configure the auto-
negotiation parameters of each PHY attached to the EMAC SW, retrieve the negotiation results, and
configure required parameters in the EMAC SW module for correct operation. The module is designed to
allow almost transparent operation of the MDIO interface, with very little maintenance from the core
processor. A single MDIO interface is pinned out to control the PHY configuration and status monitoring.
Multiple external PHYs can be controlled by the MDIO interface.
For more detailed information on the MDIO peripheral, see the 3PSW Ethernet Subsystem chapter in the
device-specific Technical Reference Manual.
8.6.3.1 MDIO Peripheral Register Descriptions
The MDIO peripheral registers are described in the device-specific Technical Reference Manual. Each
register is documented as an offset from a base address for the peripheral. The base addresses for all of
the peripherals are in the device memory map (see Section 2.10).
8.6.3.2 MDIO Electrical Data/Timing
Table 8-23. Timing Requirements for MDIO Input
(see Figure 8-18)
OPP100/OPP120/
Turbo/Nitro
NO.
UNIT
MIN
400
180
15
MAX
1
tc(MDCLK)
Cycle time, MDCLK
ns
ns
ns
ns
tw(MDCLK)
Pulse duration, MDCLK high or low
4
5
tsu(MDIO-MDCLKH)
th(MDCLKH-MDIO)
Setup time, MDIO data input valid before MDCLK high
Hold time, MDIO data input valid after MDCLK high
10
1
MDCLK
4
5
MDIO
(input)
Figure 8-18. MDIO Input Timing
Table 8-24. Switching Characteristics Over Recommended Operating Conditions for MDIO Output
(see Figure 8-19)
OPP100/OPP120/
Turbo/Nitro
NO.
PARAMETER
UNIT
MIN
MAX
100
7
td(MDCLKL-MDIO)
Delay time, MDCLK low to MDIO data output valid
ns
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Peripheral Information and Timings
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