Description of Operation
8-34
ADSP-BF537 Blackfin Processor Hardware Reference
This state is intended to be used with very restricted
receive-frame filters, so that only certain specific frames are
stored via DMA—perhaps only the frame(s) which caused the
wakeup event itself. The transmit functionality permits the proces-
sor to enqueue a list of final frame transmissions before going to
sleep.
The MAC can only transmit frames contained in DMA buffers set
up by the processor prior to entering the sleep state. Once the last
transmit frame has been sent, the transmitter and DMA channel
pauses. Note that if the last TX DMA descriptor was programmed
to signal an interrupt, the ADSP-BF536/ADSP-BF537 wakes from
sleep at the conclusion of that transmission.
Similarly, the MAC can only receive as many frames as can be
contained in the DMA buffers and descriptors allocated by the
processor prior to entering the sleep state. Once the last receive
frame has been filled, the DMA channel pauses, and if any further
frames are received (beyond the capacity of the MAC RX FIFO), a
DMA overrun occurs. Note that if the last RX DMA descriptor was
programmed to signal an interrupt, the ADSP-BF536/
ADSP-BF537 wakes from sleep after that frame was received.
Magic Packet Detection
The MAC can be programmed to detect a Magic Packet as a wakeup
event. This is enabled by setting the
MPKE
bit (Magic Packet enable) bit in
the
EMAC_WKUP_CTL
register. When the MAC receives the Magic Packet, it
sets the
MPKS
(Magic Packet status) bit in the
EMAC_WKUP_CTL
register,
which causes the Ethernet event interrupt to be asserted. The associated
ISR should clear the interrupt by writing a 1 to the
MPKS
bit; writing a 0
has no effect.
A Magic Packet is any valid Ethernet frame which contains a specific
102-byte pattern derived from the MAC’s 48-bit MAC address anywhere
within the frame after the 12th byte (after the destination and source
Summary of Contents for Blackfin ADSP-BF537
Page 42: ...Contents xlii ADSP BF537 Blackfin Processor Hardware Reference ...
Page 90: ...Development Tools 1 32 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 138: ...Programming Examples 4 26 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 340: ...SDC Programming Examples 6 84 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 606: ...Programming Examples 9 94 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 660: ...Programming Examples 10 54 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 720: ...Electrical Specifications 11 60 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 840: ...Programming Examples 13 42 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 876: ...Programming Examples 14 36 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 938: ...Programming Examples 15 62 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 958: ...Programming Examples 17 12 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 986: ...Programming Examples 18 28 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 1162: ...G 26 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 1218: ...Index I 56 ADSP BF537 Blackfin Processor Hardware Reference ...