Architecture
1853
SPNU563A – March 2018
Copyright © 2018, Texas Instruments Incorporated
EMAC/MDIO Module
32.2.18 Power Management
Each of the three main components of the EMAC peripheral can be placed in a reduced-power mode to
conserve power during periods of low activity. The peripheral clock to the EMAC peripheral is controlled
by the processor Global Clock Module (GCM). The GCM allows the application to enable or disable the
peripheral clock to the EMAC peripheral.
The power conservation modes available for each of the three components of the EMAC/MDIO peripheral
are:
•
Idle/Disabled state
. This mode stops the clocks going to the peripheral, and prevents all the register
accesses. After reenabling the peripheral from this idle state, all the registers values prior to setting
into the disabled state are restored, and data transmission can proceed. No reinitialization is required.
•
System reset.
The EMAC peripheral is reset by the system reset signal output from the System
module. Refer to the "Architecture" chapter of the Technical Reference Manual to identify the causes of
a system reset. Upon a system reset, the registers are reset to their default value. When powering-up
after a system reset, all the EMAC submodules need to be reinitialized before any data transmission
can happen.
For more information on the use of the GCM, see your device-specific Technical Reference Manual.
32.2.19 Emulation Considerations
EMAC emulation control is implemented for compatibility with other peripherals. The SOFT and FREE bits
in the emulation control register (EMCONTROL) allow EMAC operation to be suspended.
When the emulation suspend state is entered, the EMAC stops processing receive and transmit frames at
the next frame boundary. Any frame currently in reception or transmission is completed normally without
suspension. For transmission, any complete or partial frame in the transmit cell FIFO is transmitted. For
receive, frames that are detected by the EMAC after the suspend state is entered are ignored. No
statistics are kept for ignored frames.
shows how the SOFT and FREE bits affect the operation of the emulation suspend.
NOTE:
Emulation suspend has not been tested.
Table 32-9. Emulation Control
SOFT
FREE
Description
0
0
Normal operation
1
0
Emulation suspend
X
1
Normal operation