scans the 0xFFFF.FFFF.FFFF pattern in the incoming frame. The 16 repetitions can be anywhere
in the frame, but must be preceded by the synchronization stream (0xFFFF.FFFF.FFFF). The device
can also accept a multicast frame, as long as the 16 duplications of the MAC address are detected.
If the MAC address of a node is 0x0011.2233.4455, then the MAC scans for the following data
sequence:
Destination Address Source Address ……………….. FF FF FF FF FF FF
00 11 22 33 44 55 00 11 22 33 44 55 00 11 22 33 44 55 00 11 22 33 44 55
00 11 22 33 44 55 00 11 22 33 44 55 00 11 22 33 44 55 00 11 22 33 44 55
00 11 22 33 44 55 00 11 22 33 44 55 00 11 22 33 44 55 00 11 22 33 44 55
00 11 22 33 44 55 00 11 22 33 44 55 00 11 22 33 44 55 00 11 22 33 44 55 …CRC
The magic packet detection is updated in the
EMACPMTCTLSTAT
register for the received magic
packet. If the
PMT
interrupt is enabled in the
Ethernet MAC Interrupt Mask (EMACIM)
register, a
PMT
interrupt is asserted and the
EMACPMTCTLSTAT
register can be read to determine whether
a magic packet frame has been received.
20.3.10.4 Power Management Interrupts
The
PMT
interrupt signal can be asserted when a valid remote wake-up frame or magic packet is
received. The PMT interrupt signal restores the application clock and TX clock to the MAC. When
the
Ethernet MAC PMT Control and Status (EMACPMTCTLSTAT)
register is read, the
PMT
interrupt is cleared in the
EMACRIS
register at least after four clock cycles of RX clock. When
software resets the
PWRDWN
bit in the
Ethernet MAC PMT Control and Status
(EMACPMTCTLSTAT)
register, the MAC comes out of the power-down mode, but this event does
not generate at
PMT
interrupt.
20.3.10.5 Power-Down/Wake-Up Sequence
The recommended power-down and wake-up sequence is as follows:
1.
Disable the Transmit DMA (if applicable) and wait for any previous frame transmissions to
complete. These transmissions can be detected when
TI
is set in the
Ethernet MAC DMA
Interrupt Status (EMACDMARIS)
register.
2.
Disable the MAC transmit and receive state machine by clearing the
TE
and
RE
bits in the
Ethernet MAC Configuration (EMACCFG)
register.
3.
Wait until the RX DMA empties all the frames from the Rx FIFO to system memory by polling
the
RXF
field of the
Ethernet MAC Status (EMACSTATUS)
register.
4.
Enable a power management mode by setting the magic packet, global unicast or remote
wake-up enable bit in the
EMACPMTCTLSTAT
register.
5.
Enable the MAC receive state machine in the
EMACCFG
register and enter the Power-Down
mode by setting the
PWRDWN
bit in the
EMACPMTCTLSTAT
register.
6.
On receiving a valid remote wake-up frame, the
PMT
interrupt is set in the
EMACRIS
register
and the Ethernet MAC exits the Power-Down mode.
7.
Read the
EMACPMTCTLSTAT
register to clear the
PMT
interrupt, then enable the other modules
in the system and resume normal operation.
June 18, 2014
1456
Texas Instruments-Production Data
Ethernet Controller